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1
Trudel, Alain. "Effects of decarburization on the incipient melting temperature of AISI 4140 steel." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22836.
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The continuous heating to fracture test (CHF) developed at McGill was used to study the effect of decarburization on the incipient melting temperature. In the CHF test, a sample was deformed at a constant true strain rate, while its temperature is increased at a constant rate. This test allows the incipient melting temperature to be determined using a single test, instead of the several required by isothermal tensile testing. An isothermal decarburization step, to create a decarburized layer at the surface of the sample, was added prior to the CHF test.Analysis of the true stress vs temperature curves obtained by CHF testing allows the incipient melting temperature to be determined. Optical metallography was used to determine the effect of decarburization time on the observed depth of decarburization. The heat transfer characteristics of induction heating were studied, since this heating technique is known to create a significant temperature gradient at the surface of the piece being heated. Since the decarburized layer is in the high temperature zone, and also has a higher melting point due to its lower carbon content, it plays an important role in the melting process.
A phenomenological model was derived to describe the melting process. It allows for both the temperature gradient due to induction heating and the melting point gradient due to decarburization. The hypothesis is advanced that melting takes place at the position, within the sample, where the temperature profile crosses the incipient melting temperature gradient. From this study, it appears that decarburization acts so as to limit the risk of hot shortness on a workpiece being forged at high temperatures. This is because decarburization raises the IMT, and in this way widens the temperature window of optimum workability.
2
Gomez, Rodolfo Andres. "Monotonic Plasticity-Damage and Fatigue Life Model Correlations on AISI 4140 Steel." MSSTATE, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07052007-144738/.
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A microstructure-based plasticity-damage model is used to predict the mechanical behavior of commercially available AISI 4140 steel. Monotonic tension, compression and torsion tests were performed to obtain the set of plasticity and damage constants required for model calibration. Then, tension tests on Bridgman notched specimens were undertaken to study the damage-triaxiality dependence. Three different notch radii generated different levels of triaxiality at the notch. The modeled triaxiality-damage correlation was validated with SEM fracture surface analysis. Stress-strain correlations under different strain rate and temperature testing conditions were also studied. Little influence of the strain rate was observed. A preliminary study in high-porosity LENS materials was later performed, with satisfactory stress-strain correlation at two different temperatures on tension tests. Finally, a multistage fatigue model was used to predict life in AISI 4140 steel. The goal was to create a baseline for future application of these mathematical models into LENS manufactured materials in component design
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Tedesco, Marcelo Evandro. "Variação dimensional e microestrutural do aço AISI 4140 em peças usinadas por torneamento." reponame:Repositório Institucional da UCS, 2007. https://repositorio.ucs.br/handle/11338/1033.
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Precisão dimensional e qualidade de superfície usinada são fundamentais em componentes de aplicações mecânicas. Dentre as variáveis que exercem influência sobre estes fatores, está a grande quantidade de calor gerado na usinagem, que deve ser reduzida, minimizando seus efeitos na ferramenta e na estrutura superficial e sub-superficial da peça. Reduzir este calor e seus efeitos é uma das funções da lubri-refrigeração, porém, intensificamse as pesquisas com o objetivo de restringir ao máximo o uso destes fluídos. Neste trabalho, analisou-se a eficiência da lubri-refrigeração na qualidade da superfície usinada, no desvio dimensional e na variação microestrutural de amostras do aço AISI 4140 com diferentes microestruturas, usinado pelo processo de torneamento longitudinal. Observou-se que a lubri-refrigeração não teve efeito considerável sobre a qualidade da superfície usinada, não apresentando uma melhora significativa na rugosidade. Na questão dimensional observou-se que, em mais de 60% dos ensaios realizados, os resultados com e sem a presença da lubri-refrigeração mantiveram-se dentro da faixa de tolerância préespecificada, e na avaliação microestrutural, avaliando a deformação plástica, observou-se que houve uma queda na dureza da borda do material, em comparação com regiões mais próximas do centro do corpo-de-prova.Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-10-07T13:50:18Z No. of bitstreams: 1 Dissertacao Marcelo Evandro Tedesco.pdf: 2625254 bytes, checksum: b06979aea49156d0b72bf7d6ea7b3961 (MD5)
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Dimensional deviation and surface quality are fundamental components for mechanical applications. The variables that influence these factors, the quantity of heat generated must be reduced in order to minimize their effects on tool and on the superficial and sub-superficial structure of the piece. Reducing this heat and its effects is one of the cooling functions; however, the researches trying to restrict the use of those fluids. In this work, the cooling efficiency was analyzed on the surface quality, dimensional deviation and microstructural variation of AISI 4140 steel samples machined with different microstructure by longitudinal turning process. As a result, it was found that the cooling is not a significant effect on surface quality, not improving the roughness. In regard to dimensional, it was noticed in more than 60% of tests that the results with and without the presence of cooling kept between the pre-specified tolerance ranges. In the microstructural analysis, analyzing the plastic deformation, it as noticed that the hardness decrease in the edge of the sample, comparing with the center.
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Collins, Sunniva Refsnes. "Forging effects on manganese sulfide inclusions as fatigue initiation sites in AISI 4140 steel." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057696631.
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Qi, Qiang. "INVESTIGATION OF POLISHING METHODS AND SURFACE ANALYSIS AFTER MACHINING AISI 4140 ALLOY STEEL." UKnowledge, 2017. https://uknowledge.uky.edu/me_etds/107.
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AISI 4140 alloy steel has been a very common material to be investigated in automotive and aerospace industries for several decades. AISI 4140 alloy steel is chromium, molybdenum, and manganese containing low alloy steel. It has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength. The functional performance is largely determined by the surface states after machining.
The aim of the present study is to explore the polishing methods and surface analysis after machining AISI 4140 alloy steel in different cutting speeds and cooling conditions. The surface analysis includes surface roughness, hardness and residual stresses. Compared to traditional polishing, an innovative experimental work was conducted on electro-polishing technology for removing surface layer before subsurface residual stress measurement.
The results of this work show that the electro-polishing method is a significant approach for the residual stress analysis. High cutting speed and cooling conditions can improve the surface quality to achieve lower surface roughness, higher microhardness and more compressive residual stresses after machining AISI 4140 alloy steel.
6
Aguiar, Willys Machado. "Soldagem do AÃo ABNT 4140 sem Tratamento TÃrmico Posterior." Universidade Federal do CearÃ, 2001. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7272.
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O procedimento de soldagem convencional do aÃo ABNT 4140, devido à formaÃÃo de martensita na zona termicamente afetada pelo calor (ZAC), contempla um tratamento tÃrmico pÃs-soldagem para aliviar as tensÃes e melhorar a tenacidade desta zona. Esse tratamento tÃrmico, muitas vezes, se torna impraticÃvel devido a alguns fatores como tamanho da peÃa, reparo no campo e custo. A tÃcnica da dupla-camada tem sido pesquisada no sentido de se evitar este tratamento tÃrmico e garantir boas propriedades mecÃnicas da peÃa soldada. O emprego da tÃcnica da dupla-camada exige uma relaÃÃo adequada entre as energias de soldagem das camadas, para que a segunda refina e revina a ZAC grosseria da primeira, pois, nesta regiÃo a possibilidade de formaÃÃo de martensita à grande devido a sua maior temperabilidade. Neste trabalho, foi utilizado um ensaio preliminar chamado de teste de Higuchi que permitiu a escolha das energias. Em seguida foram realizadas soldagens em simples depÃsito e camada Ãnica em corpos de prova temperados e revenidos com o objetivo de avaliar o grau de refino e revenimento proporcionado pelos passes laterais. ApÃs este ensaio, foram soldados corpos de prova temperados e revenidos utilizando-se a dupla-camada para depois, atravÃs do ensaio de microdureza e metalografia, avaliar o grau de refino e revenimento porporcionados pelo uso da tÃcnica de dupla camada. A soldagem de uma junta semi-V permitiu a avaliaÃÃo da tenacidade da ZAC da primeira camada atravÃs da realizaÃÃo do ensaio Charpy. Os resultados deste ensaio mostraram que as energias absorvidas por corpos de prova soldados, com as relaÃÃes de energias de soldagem (KJ/cm) da primeira e segunda camada de 5/5 e 5/10, sÃo semelhantes as dos corpos de prova com o tratamento tÃrmico pÃs-soldagem e superior a do metal base temperado e revendido, mostrando a viabilidade de tÃcnica.The welding procedure of the conventional steel AISI 4140 due to the formation of martensite in the heat affected zone by heat (HAZ), comprises a post-welding heat treatment to relieve stresses and improve the toughness of this zone. This thermal treatment often becomes impractical due to factors such as part size, and field repair cost. The technique of double-layer has been studied in order to avoid this thermal treatment and to ensure good mechanical properties of the welded part. The use of the technique of double-layer requires an appropriate relationship between the energy of welding of the layers, so that the second and refines the HAZ revina coarseness of the first, since in this region the possibility of formation of martensite is large because of its higher hardenability . In this work, we used a preliminary test called Higuchi allowing the choice of energy. Then welds were carried out in simple deposit and single layer in specimens quenched and tempered in order to assess the degree of refining and tempering provided by lateral passes. After this test, the specimens were welded and tempered using the double-layer and then through metallography and microhardness testing, evaluate the degree of refining and tempering porporcionados to use the technique of double layer. The welding together of a semi-V allowed the evaluation of the toughness of HAZ of the first layer by conducting the Charpy test. The results of this test showed that the energy absorbed by welded specimens, with the relations of welding energy (KJ / cm) of the first and second layer of 5/5 and 5/10, are similar to those of specimens with post-weld heat treatment and superior to the base metal and tempered resold, demonstrating the feasibility of the technique.
7
Evins, Joseph Lee. "Dependence of Strength on Corrosion-Fatigue Resistance of AISI 4130 Steel." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5265.
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Automobile components are often exposed to aggressive environments as a result of aqueous salts from the road coming into contact with unprotected steel. This situation greatly reduces both the life and the appearance of the affected parts. Ultra-high strength steel parts are suspected to exhibit poor corrosion-fatigue properties and be more susceptible to corrosion in general.
In this study, the effect of strength level on the decrease in fatigue life of AISI 4130 steel when exposed to an aqueous salt solution is quantified. The observed mechanical properties including corrosion-fatigue behavior are examined with consideration to different microstructural characteristics resulting from heat treatments to the steel. The hardness and tensile properties of the test material were characterized before fatigue testing. Fatigue tests were completed in both air and salt solution to determine the effect on fatigue life of the latter environment. Following fatigue testing, the fracture surface was examined using a scanning electron microscope (SEM) to determine the failure mode.
Six strength levels of AISI 4130 steel were investigated ranging from 837 to 1846 MPa (121 268 ksi). The frequency of loading used for corrosion-fatigue tests was 1 Hz and the stress ratio for each test was constant at R = 0.1. The corrosion-fatigue tests consisted of the specimen being submerged in an aqueous solution of sodium chloride, calcium chloride, and sodium bicarbonate and fatigued until failure. The solution was maintained at room temperature with constant aeration to ensure constant oxygen levels. The parameters of interest were the applied loads and the cycles to failure.
There were four primary findings of the study. First, decreases in fatigue life of the material caused by the corrosive environment ranged from 100% in the lowest strength level to 190% in the higher strength levels. This result showed that higher strength in this steel corresponds to increasing detriment to fatigue life when the material is exposed to an aqueous salt environment. Second, evidence was found that the salt solution lowered the fatigue limit for each strength level studied in this material. All specimens that were tested in the corrosive environment failed in less than 150,000 cycles, while some specimens fatigued in the air environment experienced run-outs at over 106 cycles. Third, the decrease in fatigue life was attributed to the presence of martensite in the structure of the steel. It was noted that the higher the martensite content, the larger the decrease in fatigue life when exposed to the corrosive environment. Finally, the fracture surfaces of fatigued specimens revealed that a similar cracking mode was present for each strength level in both environments. Enhanced crack initiation was, therefore, assumed to be the cause of the decrease in fatigue life between the air and aqueous salt environments.
8
Coletta, Marcus Alberto Della. "Comparação do desempenho à abrasão dos aços AISI 4340, 4140, 5140 e 300M nitretados por plasma em diferentes condições." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-14092016-120013/.
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Os aços de ultra resistência com médio carbono e baixa liga apresentam excelentes propriedades de resistência mecânica e à fadiga além de uma elevada temperabilidade. No entanto, tais aços apresentam o fenômeno da têmpera ou de tratamentos superficiais. O aço 300M foi desenvolvido visando a ampliação desta faixa, permitindo tratamentos em temperaturas em torno de 350ºC viabilizando o emprego da técnica de nitretação do mesmo por plasma sem a consequente fragilização. Neste trabalho comparou-se as características e propriedades do aço 300M nitretado por plasma à 350ºC e 550ºC com os aços de alta-resistência AISI 4340, 4140 e 5140 nitretados à 550ºC. Variou-se as condições de tratamento de forma a verificar a influência do tempo de nitretação e de frequência de pulso nas camadas nitretadas. Verificou-se que a nitretação por plasma demostrou ser bastante efetiva para conferir resistência ao desgaste abrasivo para todos os aços nitretados. O aço 300M nitretado em 350ºC apresentou no ensaio de desgaste abrasivo comportamento similar aos demais aços nitretados em 550ºC, enquanto que o melhor resultado geral foi alcançado pelo 300M nitretado à 550ºC em CC durante 6 horas, devido à formação de uma camada dupla de levada dureza e espessura.The ultrahigh-strength steels with medium carbon and low alloy, like AISI 4340, show excellent tensile strength and fatigue properties further higher hardenability. However, these steels have the phenomenon of tempering embrittlement, that restrict the temperature of treatments after quench or surfaces treatments. The 300M steel was developed aiming the enlargement this area of application, this steel permits treatments in temperatures about 350°C what allowed to use the plasma nitriding without problems with the embrittlement. In this production were compared the properties of the nitrited layers of the 300M nitriding by plasma in 350°C and 550°C with the steels AISI 4340, AISI 4140, AISI 5140 nitriding in 550°C. Plasma nitriding conditions like time and pulse frequency were varied. It was checked that the plasma nitriding showed good performance to improve the resistance to the abrasive wear in ali the steels tested. The 300M steel nitrited in 350°C showed results similar to the others in the pin-on-disk test and the better result occurred to the 300M steel nitrited in 550°C in dC plasma during 6 hours, because of a duble compound lawyer that arouse with a high thickness and high hardness.
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Chattoraj, Indranil. "The effect of shot peening on hydrogen entry into and hydrogen embrittlement of AISI 4130 steels /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487687115924379.
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Claesson, Erik. "Development of a heat treatment method to form a duplex microstructure of lower bainite and martensite in AISI 4140 stee." Thesis, KTH, Materialvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-165084.
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Research on bainite and martensite structures has indicated that lower bainite needles have a refining effect on the lath martensitic structure. Lower bainte needles partitions prior austenite grains and will consequently have a refining effect on the subsequent formed lath martensite. Smaller austenite grains will result in smaller lath martensitic packets and blocks and will result in enhanced mechanical properties. In order to create a variation of lower bainte structure in a matrix of martensite, two different heat treating methods were tested. The work was focused towards the formation of lower bainite during isothermal heat treating in molten salt, above and below the MS-temperature. Both un-tempered and tempered samples were analyzed .Two different materials were tested, both were AISI 4140 but with a slightly difference in hardenability. The material provided by Ovako Steel is 326C and 326F the later had a higher hardenability. In order to better distinguish the two structures from each other when studied under a microscope, a variation of etching methods were tested. It was possible to create a variation of lower bainite structures in a matrix of martensite. 326F shows less amount of lower bainite and provides a higher average surface hardness before tempering.
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Paula, Marcelo Antunes de [UNESP]. "Avaliação da aplicação de fluído de corte no torneamento do aço inoxidável martensítico AISI 410 tratado termicamente." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144304.
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Pró-Reitoria de Pós-Graduação (PROPG UNESP)
Muitos materiais são utilizados para diversas aplicações em projetos de engenharia. Os aços inoxidáveis martensíticos que são ligas de ferro e cromo (11-18%) com teor de carbono acima de 0,1% são aplicados na fabricação de válvulas, bombas de equipamentos, ferramentas de cutelaria, eixos acionadores, hastes de pistão, componentes de turbinas hidráulicas e instrumentos cirúrgicos. A evolução das propriedades e desempenho dos materiais utilizados em componentes para aplicações em engenharia é contínua ao longo dos anos, consequentemente os processos e as ferramentas utilizadas para fabricação desses componentes precisam evoluir conjuntamente. A proposta desse trabalho é avaliar o desempenho das ferramentas de corte de Metal Duro revestidas pelos processos (PVD-Physical vapor deposition e CVD-Chemical vapor deposition) na usinagem a seco e MQL do aço inoxidável martensítico AISI 410 tratado termicamente e a qualidade do acabamento superficial da peça, nas condições de corte com (vc = 125-150-175 m/min, f = 0,1-0,25 mm/rev e ap = 0,5 mm). A análise dos desgastes das ferramentas de corte foi realizada com auxilio de microscópios. A medição da rugosidade foi realizada com auxílio de um rugosímetro. Resultados finais evidenciaram que a ferramenta com revestimento CVD apresentou um melhor desempenho em ambas às condições de corte porque a amostra teve um bom acabamento superficial. A ferramenta com revestimento PVD apresentou avarias durante a realização dos ensaios, as avarias ocorreram na ferramenta em ambas às condições de corte durante os testes, primeiramente, na forma de pequenas lascas, em seguida, ocorrendo à quebra da ferramenta. Os cavacos obtidos durante os ensaios de uma forma geral foram na forma de lascas.
Many materials are used for various applications in engineering projects. The Martensitic Stainless Steels are alloys containing from 11.5 to 18% of chromium and 0.09 to 0.15% of carbon, which are widely used in the manufacturing of valves, pumps, cutlery tools, drive shafts, piston rods, hydraulic turbine components and surgical instruments. The evolution of the properties and performance of materials used in components for engineering applications is continuous over the years, therefore processes and tools used to manufacture these components must develop together. The purpose of this work is to evaluate the performance and wear of coated carbide tools (PVD - Physical vapor deposition e CVD - Chemical vapor deposition) in dry machining and MQL of Martensitic Stainless Steel AISI 410 heat-treated and the quality of workpiece surface finishing in cutting conditions (vc = 125-150-175 m/min, f = 0,1-0.25 mm/rev, ap = 0.5 mm). The tool wear analysis was realized with the aid of microscopes. The measurement of roughness was obtained with the aid of roughness meter. Final results showed that the coated carbide tool (CVD) performed well in both cutting conditions because the piece had a good surface finishing, the flank wear were not significant for the tested cutting lengths and the tool no damage showed. The coated carbide tool (PVD) showed damage in both cutting conditions during the tests, firstly on shape of small splinters, then to break the tool. The chips were obtained during tests on shape of small splinters.
CAPES: 175.715
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Severiano, Josemberg de Assis. "Estudo dos mecanismos de danos de válvulas de injeção de água de poços de petróleo fabricadas em aço inoxidável AISI 316 e AISI 410." Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/3534.
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Austenitic and martensitic stainless steels are applied in the manufacturing of
water injection valves for oil exploration. Studies were performed of damage
mechanisms of stainless steel AISI 316 and AISI 410 used in the manufacture of
injection valves. Laboratory and field tests were performed that included: 1) installation
and monitoring of field samples; 2) characterization of the injection water; 3) Samples
manufacture of AISI 316 stainless steel in the annealed condition and AISI 410 under
the following conditions: a) sferoidized with low hardness, b) quenched and tempered to
400 HV hardness; c) nitrided; 4) corrosion test by immersion and electrochemical to
evaluate the corrosion rate; 5) erosion tests. The alloy´s characterizations were achieved
by chemical analysis composition, microstructural, hardness and surface damage
analysis of field samples. Results showed that the AISI 410 steel with low hardness has
lower corrosion and erosion strength. The nitriding treatment increased the corrosion
resistance, and quenching and tempering increased the corrosion and erosion strength of
the AISI 410 alloy. The damage mechanism of the valve is predominantly corrosion.
Valves manufactured on stainless steel AISI 410 are damaged by generalized corrosion
after mean two months of use, while the valves manufactured in AISI 316 steel survive
five months mean, and after it they experience damage by localized corrosion.Os aços inoxidáveis austeníticos e martensíticos são utilizados na construção de válvulas de injeção de água para exploração de petróleo. Foram realizados estudos dos mecanismos responsáveis por provocar danos nos aços inoxidáveis AISI 316 e AISI 410 empregados na fabricação das válvulas de injeção. Para isto, foram executados ensaios de laboratório e de campo que incluíram: 1) instalação e acompanhamento de amostras de campo; 2) caracterização do meio; 3) fabricação de cupons dos aços inoxidáveis AISI 316 no estado recozido e do AISI 410 nas seguintes condições: a) esferoidizado de baixa dureza, b) temperado e revenido para 400 HV de dureza; c) nitretado; 4) ensaio de corrosão por imersão e eletroquímico para avaliar taxa de corrosão; 5) teste de erosão. As caracterizações das ligas foram feitas pelas análises da composição química, microestruturais, microdureza e de danos da superfície das amostras. Resultados apontaram que o aço AISI 410 sem tratamento térmico tem baixa resistência à corrosão e erosão. Notou-se que o tratamento de nitretação aumentou a resistência à corrosão, e que o tratamento de têmpera e revenido elevou a resistência à corrosão e à erosão da liga AISI 410. Pelos testes realizados observou-se que o mecanismo de dano das válvulas é predominantemente por corrosão. As válvulas fabricadas em aço inoxidável AISI 410 sofreram danos por corrosão generalizada em dois meses de uso em média, enquanto as válvulas fabricadas em aço AISI 316 resistem cinco meses em média, e passam a sofrer danos por corrosão localizada.
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Coelho, Fernando. "Influência do ângulo de preparação da junta no aço tubular AISI 4130 soldado pelo processo TIG." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153585.
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As indústrias metalúrgicas de diversos segmentos buscam continuamente aperfeiçoar seus processos e reduzir custos de produção de estruturas metálicas. Variações em um processo térmico padronizado ou na configuração do produto podem causar alterações na microestrutura e nas propriedades mecânicas do, bem como, no comportamento mecânico do material. Assim, o presente estudo avaliou os efeitos das variações do ângulo de chanfro da junta em tubos de aço redondos AISI 4130 sem costura, quando soldados no processo TIG (Tungsten Inert Gas). Os tubos foram cortados com arco de plasma e preparados com ângulos, 30°, 45° e 60°, e 1 milímetro de altura da raiz. A soldagem foi realizada em dois passes, sendo o primeiro passe na raiz pelo método autógeno e o segundo de preenchimento com metal de adição arame-eletrodo AWSER80S-B2. As juntas soldadas foram submetidas a análises metalográficas de macrografia e microscopia óptica, para avaliação metalúrgica das zonas fundida e afetada pelo calor. Também foi realizado ensaio mecânico de tração e microdureza Vickers para verificar o desempenho mecânico e a dureza do material. A variável de interesse do estudo foi evidenciada por meio da estabilização do processo de corte e soldagem com uso de uma máquina rotativa digital desenvolvida no presente estudo. Os resultados obtidos evidenciaram uniformidade entre os cordões produzidos, variações nas geometrias dos cordões, no tamanho de grão e nas fases de transformação da microestrutura, com impacto na dureza da ZF (Zona Fundida), assim como no desempenho mecânico verificado com ensaios de tração. Conclui-se que, variações no ângulo da junta alteram a área de contato do arco com a poça de fusão, assim como, da poça de fusão com a ZAC. Com isso têm-se diferentes eficiências de transferência de energia térmica por condução, com diferentes ciclos térmicos que resultam em fases e transformações metalúrgicas distintas.
The metallurgical industries at several segments are continuously looking for improving their process and decrease metallic structures production costs. Modifications in a standardized thermal process or in the product configuration can leads to microstructure changes and in the mechanical properties,as well, in the mechanical behavior from the material. Thus, the current study made an assessment of the angle variation effect in steel round tubes joint AISI 4130 without seam, when welded by mechanized TIG process (Tungsten Inert Gas). The steel tubes were cross cut with plasma and prepared in three different angles 30°, 45° and 60°, with 1 millimeter height of root. The welding was made in two passes, the first one in the root by autogenous methode and the second one for filling using eletrode wire AWS ER80S-B2. The welded joints were submitted to metallographic test of macrograph and optical micrographics for metalurgical assessment in the melted zone and the heat affected zone. In addiction was made traction tests and micro hardness Vickers for verify the mechanical behavior and hardness from the material. The interest variable in this study, was evidenced by cut and welding process stabilization using a digital rotative machine developed in this study. The obtained results showed uniformity between weld beads produced with variation in the geometry, as well, in the grain size and in the fases transformations from the microstructure, with impact in the melted zone hardness profile, and in the mechanical properties verified by traction test. It´s pissible conclude that joint chanfer angle variations cause changes in the contact area size between the arc and the molten puddle, and between the molten puddle with the base metal. With this, diferent energy transfer efficency by conduction are obtained producing diferent thermal cicle, that can result in diferent metallurgical fases and microstructure transformations.
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Bastidas, Freddy Galileo Santacruz. "Estudo comparativo do desgaste erosivo do tipo lama, do aço inox martensitíco AISI 410 com os revestimentos carbeto de tungstênio 86WC-10Co4Cr, obtido por HVOF e o elastômero PUR comercial." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/184870.
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Na indústria hidrometalúrgica, diversos materiais são utilizados para a construção dos equipamentos, a fim de satisfazer as necessidades dos processos que estão sujeitos, tendo em conta a importância deles em condições complexas, tais como erosão e a corrosão. Neste trabalho é avaliado o comportamento de um aço inoxidável martensítico AISI 410 tratado termicamente com têmpera e revenimento, frente aos revestimentos Carbeto de Tungstênio (86WC-10Co4Cr) obtido por aspersão térmica (High Velocity Oxygen Fuel-HVOF), e um elastômero PUR comercial MetaLine 785 em condições de desgaste do tipo lama, analisando a perda de volume, a determinação da área e profundidade erodida das amostras, para os ângulos de incidência de 30∘ e 90∘ entre o eixo de simetria do fluxo do fluido e a superfície das amostras. Os ensaios foram realizados para os diferentes tipos de materiais em um equipamento para ensaios simulados de lama, desenvolvido como parte da pesquisa no LACER (Laboratório de Materiais Cerâmicos) da Universidade Federal do Rio Grande do Sul (UFRGS), sob controle de parâmetros como ângulo de impacto e sua velocidade, temperatura de ensaio e concentração de partículas erosivas na suspensão, neste caso foi usada alumina eletrofundida ALO marrom da companhia Treibacher. Realizou-se a caracterização dos materiais, na sua microestrutura Microscopia Eletrônica de Varredura (MEV), Microscopia Óptica (M.O), espessura, rugosidade, porosidade, microdureza e estruturalmente na identificação de fases Difração de Raios X (DRX), Espectroscopia por Energia Dispersiva (EDS), o analise térmico Perda ao Fogo (LOI) para o caso do elastômero PUR, e a distribuição de tamanho de partícula (LG) e morfologia para o erodente. Com a pesquisa conseguiu-se estabelecer as relações entre o desgaste erosivo por lama e as propriedades físicas relacionadas aos materiais avaliados, nas condições estabelecidas no ensaio de erosão do equipamento, e concluiu-se que o revestimento de 86WC-10Co4Cr carbeto de Tungstênio apresentou uma melhor resistência ao desgaste erosivo tipo lama, em comparação com o aço inoxidável martensítico AISI 410 e o elastômero PUR comercial MetaLine 785.In the hydrometallurgical industry, many materials are used in the construction of the equipment in order to satisfy the needs of the processes to which they are subjected, taking into account their importance in complex conditions such as erosion and corrosion. In this work, the behavior of a quenched and tempered AISI 410 martensitic stainless steel is compared to tungsten carbide (86WC-10Co4Cr) obtained by thermal spray (High Velocity Oxygen Fuel - HVOF) and to a commercial elastomer PUR MetaLine 785 under slurry erosion conditions. Volume loss, area determination and eroded depth of the samples were analyzed at angles of incidence of 30∘ and 90∘ between the axis of symmetry of the fluid flow and the surface of the samples. The tests were carried out for the different types of materials in a slurry erosion simulation device, developed as part of the research in LACER (Laboratory of Ceramic Materials) of the Federal University of Rio Grande do Sul (UFRGS), via the control of parameters such as angle and speed of impact, test temperature and concentration of erosive particles in the suspension. In this case, electrofused brown ALO alumina (Treibacher) was used. The materials were characterized with regard to their microstructure (SEM), thickness, roughness, porosity, microhardness, structure in the phase identification (DRX) (EDS), thermal analysis (LOI) in the case of the PUR elastomer and the particle size distribution (LG) and morphology for the erodent. The research was able to establish the relationships between the slurry erosive wear and the physical properties related to the evaluated materials, under the conditions established in the erosion test of the equipment. It was concluded that the coating 86WC-10Co4Cr tungsten carbide presented better resistance to the slurry erosion wear when compared to AISI 410 martensitic stainless steel and the PUR commercial elastomer MetaLine 785.
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Deitos, Filho Marco Antônio. "Influência das variáveis do processo de soldagem TIG alimentado duplo arame quente na diluição e morfologia de cordões de solda de inconel 625 depositados em um aço AISI/SAE 4130." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/1990.
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Equipamentos utilizados na produção offshore de petróleo estão sujeitos a danos severos devido à exposição a compostos corrosivos presentes no fluido produzido. Por isso, materiais resistentes à corrosão, como a superliga à base de níquel UNS N06625 (Inconel® 625), são usados em áreas de passagem de fluido de produção. Entretanto, o elevado custo desta liga restringe sua utilização em todo o equipamento. Como solução para este problema são produzidos equipamentos com materiais de menor custo e revestidos com a liga mais nobre. Para esses revestimentos o processo de soldagem TIG alimentado duplo arame quente é tido opção por produzir soldas com qualidade e produtividade. O objetivo desse trabalho foi determinar a influência da corrente média (Im), velocidade de soldagem (Vs), velocidade de alimentação (Va), corrente do material de adição (Ia) e composição do gás de proteção (Gs) sobre a diluição (D), penetração (P), largura (L) e reforço (R) dos cordões de solda depositados pelo processo de soldagem TIG alimentado duplo arame quente sobre um aço AISI/SAE 4130. Para essa análise foi utilizado um planejamento DOE (Design of Experiments) composto central com cinco fatores totalizando trinta e duas (32) condições de aplicação dos cordões. Medições de áreas e dimensões de largura, penetração e reforço foram realizadas nas seções transversais dos cordões depositados utilizando-se um estereoscópio e software de análise de imagens. Além disso, análises dos elementos químicos, nessas seções, foram realizadas utilizando-se espectrometria de energia dispersiva, para determinar o teor do elemento Fe e, por consequência, a diluição. Para a análise do comportamento das variáveis e determinação de um modelo empírico utilizou-se a metodologia de superfície de resposta (RSM – Response Surface Methodology). Verificou-se que todas as variáveis influenciaram na diluição, e com o modelo adotado foi possível obter valores de diluição mínima de 6,37%. Adicionalmente, foram determinadas penetração na faixa 0,37 a 2,16 mm, largura na faixa de 8,09 a 10,04 mm e reforço entre 1,93 a 3,16 mm.Equipment used in offshore oil production are subject to severe damage due toexposure to corrosive compounds present in the produced fluid. Therefore, corrosion resistant materials such as nickel base super alloy UNS N06625 (Inconel® 625), are used in the production fluid passage areas. However, the high cost of this alloy limits its use in all equipment. As a solution to this problem equipment with lower cost materials, overlaid with the noblest alloy, are manufactured. For these overlays the TIG twin hot wire welding process is seen as an option for generate quality weld with productivity. So the aim of this study is to determine the influence of the average current (Im), welding speed (Vs), feed rate (Va), filler material current (Ia) and shielding gas composition (Gs) on the dilution (D), penetration (P), width (W) and reinforcement (R) of the weld beads deposited by TIG twin hot wire welding process on steel AISI / SAE 4130. For this analysis it was used a DOE (Design of) central composite five factors planning totalling thirty-two (32) deposition conditions of weld beads. Using a stereoscopic and image analysis software, measurements of areas and dimensions of width, penetration and reinforcement were made in cross sections of the deposited beads. Furthermore, analysis of the chemical elements in these sections were performed using energy dispersive spectrometry to determine the content of Fe element and hence the dilution. To analyse the behaviour of variables and determine an empirical model, the response surface methodology (RSM - Response Surface Methodology) was used. It was found that all variables influence the dilution, and for the adopted model the minimal dilution obtained was 6.37%. In addition, It was obtained penetration between 0.37 and 2.16 mm, width ranging from 8.09 to 10.04 mm and reinforcement between 1.93 to 3.16 mm.
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BATISTA, Valmir Rodrigues. "Efeito do processo de soldagem e da temperatura de preaquecimento sobre a susceptibilidade à fragilização por hidrogênio de juntas soldadas dissimilares utilizadas no setor offshore da indústria do petróleo." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1043.
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CNPq
Neste trabalho é apresentado um estudo sobre a susceptibilidade à fragilização por hidrogênio de juntas soldadas de metais dissimilares presentes em equipamentos submarinos da indústria do petróleo, as quais ficam submetidas a condições de uso que envolvem esforços mecânicos severos, em ambientes corrosivos, proveniente da água do mar e do fluido petrolífero. O objetivo dessa pesquisa foi avaliar o efeito da utilização dos processos Plasma Pó (PTA-P) e MIG para a aplicação de "amanteigamentos" com Liga de Ni sobre a susceptibilidade à fragilização por hidrogênio de juntas soldadas de aços dissimilares utilizadas em aplicação offshore utilizando diferentes temperaturas de preaquecimento e interpasse e também comparar os resultados para dois aços para válvula, o AISI 8630M e AISI 4130. O processo de soldagem utilizado para a união das juntas foi o processo MIG utilizando-se como metal de adição o arame eletrodo, Inconel-625 (ER NiCrMo-3) de 1,2 mm de diâmetro. Os dois aços foram submetidos a três diferentes combinações de temperaturas de preaquecimento e interpasse antes dos amanteigados pelos processos PTA-P e MIG. Após a etapa de amanteigamento foram realizadas análises de composição química por EDS, microestruturais por MO e MEV, e de microdureza antes e depois do TTAT. Em seguida foram executadas as soldagens de união pelo processo MIG. As amostras de tração foram previamente hidrogenadas simulando as condições existentes de proteção catódica em ambiente submarino. O aumento das temperaturas de preaquecimento e interpasse resultou em maior refino dos grãos da ZTA, entretanto proporcionou aumento da média de sua microdureza e de sua extensão, e em maior migração de Fe do MB para o MS, resultando em maior fragilização por hidrogênio. Pelo processo PTA-P houve uma menor diversidade e frequência de incidência de zonas parcialmente diluídas (ZPD), sendo encontradas apenas ZPD do tipo contínua, enquanto que pelo processo MIG foram encontradas ZPD do tipo descontínua, com diferentes morfologias. O TTAT proporcionou uma significativa redução de 20% a 44% nos valores da microdureza da ZTA. Com base nos níveis de deformação e Índice de Fragilização (IF), o aço AISI 4130 apresentou os melhores resultados com relação à fragilização por hidrogênio.
This Thesis presents a study about hydrogen embrittlement susceptibility of dissimilar metals welded joints present in oil industry equipment, specifically in valves connections with pipes for the oil transport, which are subject to use conditions involving severe mechanical stresses in corrosive environments, from the seawater and the oil fluid. As the valves steel are martensitic its heat affected zone (HAZ) may be susceptible to hydrogen embrittlement not only from cathodic protection but also from the seawater and H2S. Therefore, to prevent this potential embrittlement and consequently crack formation in these regions of the welded joint, is used as nickel alloy filler metal. Therefore, the part of martensitic steel previously undergoes a "buttering" process which consists of applying layers of Ni deposited by welding. The welding process used for the union of the joints was the MIG process using as filler metal the Inconel-625 (ER NiCrMo-3) wire electrode 1.2 mm in diameter. Two steels were buttering, AISI 8630M and AISI 4130. Both were subjected at the three different combinations of preheat and interpass temperatures. For the buttering realization, the same alloy, in powder form, was used by Plasma powder process (PTA-P). To evaluate the efficiency of the PTA-P process in buttering operation it was compared with other buttering performed by MIG process with the same filler metal of the weld joint. After buttering the samples were subjected to post welding heat treatment (PWHT). Chemical composition analyses were performed by Energy Dispersive Spectroscopy (EDS), microstructure by Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), and microhardness. After the welding the samples were machined and hydrogened using a process similar to those used for cathodic protection and submitted to tension tests. The Increase in the preheat and interpass temperature resulted in higher refining the grains of the HAZ however it, increased its average microhardness and extension, promoted greater Fe migration from MB to the buttering, increasing the hydrogen embrittlement. The use of PTA-P process promoted a very lower incidence and diversity of partially diluted zone (PDZ), being found only continuous PDZ. The PWHT promoted a reduction from 20% to 44% of hardness values. Based on the deformation levels and Embrittlement Index (EI), the AISI 4130 steel showed the best results with respect to hydrogen embrittlement.
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Santos, Poliana Rochele F?lix dos. "Estudo da viabilidade t?cnica para obten??o de superf?cie duplex em a?o inoxid?vel martens?tico AISI 410 atrav?s do processo de deposi??o a plasma por gaiola cat?dica." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12773.
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Previous issue date: 2013-03-01Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The technique of plasma nitriding by the cathode cage mainly stands out for its ability to produce uniform layers, even on parts with complex geometries. In this study, it was investigated the efficiency of this technique for obtaining duplex surface, when used, simultaneously, to nitriding treatment and thin film deposition at temperatures below 500?C. For this, were used samples of AISI 41 0 Martensitic Stainless Steel and performed plasma treatment, combining nitriding and deposition of thin films of Ti and/or TiN in a plasma atmosphere containing N2-H2. It was used a cathodic cage of titanium pure grade II, cylindrical with 70 mm diameter and 34 mm height. Samples were treated at temperature 420?C for 2 and 12 hours in different working pressures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with micro-analysis by Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and analysis of Vickers Microhardness were used to investigate coating properties such as homogeneity and surface topography, chemical composition, layer thickness, crystalline phase, roughness and surface microhardness. The results showed there is a direct proportionality between the presence of H2 in plasma atmosphere and the quantity of titanium in surface chemical composition. It was also observed that the plasma treatment at lowpressure is more effective in formation of TiN thin film
A t?cnica de nitreta??o a plasma por gaiola cat?dica vem se destacando, principalmente, pela sua capacidade de produzir camadas uniformes mesmo em pe?as com geometria complexa. Neste trabalho, investigou-se a efici?ncia desta t?cnica para obten??o de superf?cie duplex, quando utilizada, simultaneamente, para tratamento de nitreta??o e deposi??o de filmes finos em temperaturas inferiores a 500?C. Para tal, foram utilizadas amostras do a?o inoxid?vel martens?tico AISI 410 e realizados tratamentos a plasma, combinando a nitreta??o e deposi??o de filmes finos de Ti e/ou TiN, em uma atmosfera contendo N2-H2. Foi utilizada uma gaiola cat?dica de tit?nio puro grau II em forma cil?ndrica, com 70 mm de di?metro e 34 mm de altura. As amostras foram tratadas numa temperatura de 420?C, com dura??o de 2 e 12 horas e em diferentes press?es de trabalho. Microscopia ?ptica (MO), Microscopia Eletr?nica de Varredura (MEV) com microan?lise por Espectroscopia de Energia Dispersiva (EDS), Difra??o de Raios-X (DRX), Microscopia de For?a At?mica (MFA) e ensaio de Microdureza Vickers foram empregados para investigar as propriedades do revestimento, tais como homogeneidade e topografia superficial, composi??o qu?mica, espessura da camada, fases cristalinas, rugosidade e microdureza superficial. Os resultados mostraram existir uma proporcionalidade direta entre a presen?a de H2 na atmosfera do plasma e a quantidade do elemento qu?mico tit?nio na composi??o qu?mica superficial. Observou-se, tamb?m, que o tratamento a plasma em baixa press?o ? mais eficaz na forma??o do filme fino de nitreto de tit?nio
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Chipalkatti, Jayprakash. "Modeling of austenite decomposition in an AISI 4140 steel." Thesis, 1999. http://hdl.handle.net/2429/9090.
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The final mechanical properties and also the distribution of residual stresses in a
heat treated product, depend upon the various microstructural constituents. In heat
treatment operations, in order to predict the final properties, it has become increasingly
important to be able to predict the final microstructure distribution for a given thermal
history. Mathematical models of microstructure prediction are a useful tool for this
purpose as they eliminate the need for experimentation.
The characterization of the kinetics of austenite decomposition to equilibrium
and/or non equilibrium phases in a low alloy steel, such as AISI 4140, by performing
isothermal transformation experiments is time consuming and hence not cost effective.
Further, to generate meaningful and accurate data with respect to the various stages of the
progress of the austenite decomposition, many experiments are required. Kirkaldy's
model, involving the transformation kinetics of the various possible reaction products,
provides a very useful tool in this regard as this model is based on only the chemical
composition and the austenite grain size of the steel. By observing certain limitations of
this model, especially for low alloy steels, Li and co-workers have proposed
modifications to this model. The Kirkaldy model along with the model proposed by Li
and co-workers is assessed in the present work.
The purpose of this study was to characterize the austenite decomposition kinetics
under continuous cooling conditions in a AISI 4140 steel by applying Kirkaldy's model
and Li's model and to test the results of these models by perforating GLEEBLE
controlled continuous cooling experiments on this steel. The validity of the Kirkaldy
model and the Li model was tested in two different ways. First, the calculated response was compared with the published TTT diagram for a given chemistry and y grain size for
an AISI 4140 steel. The calculated response was subsequently tested using the
experimentally measured CCT data for a different AISI 4140 steel.
As the characterization of continuous cooling kinetics requires knowledge of the
phase diagram, a mathematical model based on thermodynamic equations is used to
derive the phase diagram for this steel. The model is based on the equality of chemical
potentials for each of the alloying elements in the phases that are in equilibrium. The
results of this model are then used in modeling the isothermal and continuous cooling
transformation kinetics.
It was observed that Kirkaldy's and Li's models both yield a reasonably good
prediction of the TTT curve for this steel, when compared to a published TTT diagram
for this steel. Under continuous cooling conditions, the microstructures predicted by the
Li model are closer to the experimentally observed microstructures than are the Kirkaldy
model predictions.
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Liang, Nai-Wen, and 梁乃文. "Composite treating on the nitriding/plasma arc quenching of AISI 4140 alloy steel." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/12236519025116628340.
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Jing-YuLin and 林敬淯. "Impact Behaviour and Microstructural Evolution of AISI 4140 Alloy Steel over Wide Temperature Range." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/67857328587436885701.
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Shun-MingWang and 王舜民. "Adiabatic Deformation and Fracture Behaviour of AISI 4140 Alloy Steel under Extreme High Shear Loading." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/06906213160187723321.
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CHENG, KAI-HAN, and 鄭楷翰. "The Growth of Phosphate Coating Layer with Different Zn/Mn Ratio on AISI 4140 Alloy Steel." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/44wa7f.
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碩士國立高雄應用科技大學
機械工程系
106
Phosphate coating is widely used in hand tools, automobiles, marine anti-corrosion, painting and other industries, because the phosphate coating can form a stable and insoluble coating on the metal material, which can effectively as a barrier to block avoid corrosion of metal materials like moisture, oxygen, corrosive substances, etc.Phosphate coating is mainly classified into zinc phosphate coating and manganese phosphate coating. Currently, most of the phosphate coating research focuses on only one kind of each phosphate coating. The study of comparison between zinc phosphate coating and manganese phosphate coating is rare. In this study, we used chemical treatment to grow zinc phosphate, manganese phosphate, and composite phosphate coating on AISI4140 alloy steel. By changing the Zn/Mn ratio in the phosphating solution, different zinc/manganese ratio of composite phosphate coatings were grown. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were used to analyze the surface morphology, element content, coating structure. Spectrophotometer was used to analyze its optical properties, and coating weight was measured by removing it from metal surface using chromic acid in order to determine the effect of Zn/Mn ratio on the phosphate coating. To understand the process of phosphate coating formation, analysis of the surface morphology, element content, and structure of the resulting phosphate coating was performed under different phosphating times. The experimental results show that the zinc phosphate coating has a large plate-like structure and the manganese phosphate coating with a granular structure. The reflectivity of the phosphate coating is changed with the zinc-manganese ratio. The zinc phosphate coating has the highest reflectance, and the reflectance decreases with decreasing zinc-manganese ratio.The composite zinc phosphate coating is the most corrosion-resistant, and corrosion resistance decreases with decreasing zinc-manganese ratio. The grow rate of zinc phosphate coating formation was the fastest, followed by the composite phosphate coating, and the slowest was the manganese phosphate coating.
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Mu-ShiunHsieh and 謝牧勳. "Effects of Temperature and Strain-Rate on the Dynamic Shear Properties of AISI 4140 Alloy Steel." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/57976366054383787394.
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Chen, Hong Kui, and 陳宏魁. "Study of BTA Addition on the Wear-Corrosion Behavior of Aluminum Bronze and AISI 4140 Steel in 3.5%NaCl solution." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/33871387469377779029.
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碩士清雲科技大學
機械工程系所
97
1,2,3-benzotriazole (BTA) could interact with the surfaces of copper and its alloy to form Cu-BTA film in corrosive environments, and has long been known as an efficient inhibitor for the general corrosion of copper and its alloy in many industry applications. Recently, the occurrence of intergranular corrosion (IGC) of copper in 3.5% NaCl solution in the presence of 1×10-3 M BTA was reported. Both cast and wrought aluminum bronzes offer a good combination of mechanical properties and corrosion resistance. Aluminum bronzes well known for its good sliding properties, is frequently applied as tool material in sheet metal forming (SMF) of stainless steel, e.g. for the production of washing, refrigeration and cooking equipment. The purpose of this study is to investigate the effect of BTA addition with different concentrations (1×10-3 M and 5×10-3 M) on the wear-corrosion protection ability of aluminum bronze sliding against AISI 4140 steel in 3.5% NaCl solution. The wear-corrosion experiment was performed by using a block-on-ring surface friction manner, aluminum bronze as the block and AISI 4140 steel as the friction ring. The wear conditions were under fixed rotation speed of 200 rpm and with different applied normal loads of 10g, 20g, 50g and 100g. The friction force was measured with respect to testing time during wearing test. The friction coefficient (µ) can be calculated by dividing the applied normal load. Also, the wear loss was measured by weighing the specimen before and after the wear-corrosion test. SEM was used to analyze the surface morphology of the specimens after wear-corrosion test. The experimental results indicated that in 3.5% NaCl solution without BTA addition, the friction coefficient and wear loss increased with increasing loads, and aluminum bronze showed the less wear loss than AISI 4140steel. Only a slight mechanical worn surface for aluminum bronze was observed, whereas AISI 4140 steel showed an serious wear-corrosion failure surface. As after BTA adding into 3.5% NaCl solution, both aluminum bronze and AISI 4140 steel exhibited an good ability for wear-corrosion protection. Especially, high BTA concentration showed a significant decrease of friction coefficient and wear loss, and then separate two parts, one is original material proceeding static electrochemistry potentiodynamic experiment that can prove BTA to have superior protection, another part is dynamic electrochemistry to wear with ceramics, and then to measure signal side anti-corrosion, the potentiodynamic show the date and curve, so we can know that BTA have good anti-corrosion and reduce the friction coefficient, weight loss.
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Juang, Yunn-Ching, and 莊運清. "Laser Welding of AISI 4150 Steel." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/40207094820888561734.
Full textAbstract:
碩士國立海洋大學
材料工程研究所
84
A study of mechanical properties of the AISI 4150 steel plate and laser welds, which undergone various heat treatment was to be investigated and its microstructure effect, as well as the residual stress effects of laser weldson the fatigue properties. Experimental results reveals that the microstructureof the alloy subjected to a 250℃ austempering treatment is a mixture of lowerbainite and temper martensite. The 300℃ treated specimen is lower bainite. Thefatigue crack growth rate(FCGR) of the plate decreased, with increasing the treating temperature. Because of the difference of microstructure, the FCGR ofaustempering treated specimen is lower than that of tempering treated. By the double effects of residual stress and microstructure, the fatigue crack growthtest of the laser welds shows excellent fatigue properties. Both of the plate and laser welds specimen treated by 300℃, then treated by 550℃ temperingagain, its fatigue properties shows similar to the specimen that quench and 550℃ tempered directly.
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Tu, Chia-Hsun, and 杜佳勳. "The Microstructural Study of Transformation in AISI 410 Stainless Steel." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/64118228835231824015.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
86
AISI 410 is the progenitor in the commercial low-carbon steels of the martensitic class. The research proposal is concerned with the study on the isothermal transformation in AISI 410 just above the Ms tempermature for the purpose of exploring thr corresponding microsturcture. In order to fully understand the marensitic transformation in this steel , a series of continuous cooling experiments will also be carried in a dilatromic dilatometer of Theta Industries Inc. The tempered martensite structure and the effect of pro-austensite deformation to transformation will also be studied.
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Tau, Lin, and 陶霖. "Microstructural Effects of AISI 4130 Steel on Hydrogen Assisted Fatigue Crack Propagation." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/20031903768876510369.
Full textAbstract:
博士國立臺灣大學
材料科學(工程)研究所
84
The main objective of this research has been to carry out a systematic study on the influences of various microstructures of a popular structural steel, AISI 4130 steel, on hydrogen-enhanced fatigue crack propagation. Some important effects have been discussed in this work, including those of microstructure, strength, hydrogen permeation, tempering temperature for tempered martensitic structures, and isothermal treating temperature for bainitic structures. In this work, some conclusions could be outlined: (1) For ferrite/pearlitic structures, the distribution of ferrite/pearlite along the path of hydrogen penetration affected hydrogen diffusivity deeply. Then the results of hydrogen diffusivity can be applied to explain the hydrogen-assisted fatigue crack propagation behavior of the banded and random ferrite/ pearlite structures successfully. (2) The variation of hydrogen-assisted fatigue crack growth rates of specimens sampled from different orientations for banded ferrite/ pearlitic structure was very significant, slight for random in the random ferrite/pearlitic structure. (3) A similar hydrogen-enhanced fatigue crack growth behavior and a transgranular fracture mode were found in bainitic structures, though they have different tensile strength and hydrogen permeation rate. (4) The hydrogen-assisted fatigue crack propagation rate of tempered martensitic structures increased as yield strength increased. In higher strength tempered martensites, an irregular fracture mode, in which the intergranular crack propagated easily near surface of specimen, was found. (5) The microstructural effect was the dominant factor on the hydrogen-assisted fatigue crack growth behavior. Alternatively, the strength effects could not been featured systematically.
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Hsu, Ching-Chiu, and 徐進秋. "Study on Erosion Wear Behaviors of AISI 304/410 Stainless Steel Weldments." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/7j7423.
Full textAbstract:
碩士國立臺北科技大學
材料科學與工程研究所
96
It is known that AISI 304 austenitic stainless steel is most commonly used due to the advantages of good corrosion resistance, weldability, and formability. In addition, AISI 410 martensitic stainless steel possesses excellent high-temperature strength, wear resistance, and fracture toughness, and it has been widely used in wall and blanket structure, pipes in nuclear power plant reactors,and turbine. In this study, both of 304 and 410 stainless steels were separately divided into the unwelded and welded conditions , and four types of them were adopted as experimental materials to perform erosion tests with an eroding carrier of Al2O3 particles under the different incident angles. The results showed that erosion resistance of the rolled 304 is better than of annealed 410 under thr unwelded condition due to its higher hardness . After the welding, the microstructure of 304 was not changed in spite of the bead and heat affected zone (HAZ), however, microstructure of 410 consisted of austenite and ferrite mixed phases in the bead as well as martensite phase in HAZ. As a result, the welded 410 showed the best erosion resistance during all the specimens. For all specimens, the maximum erosion rate of all of them occurred at an incident angle of 30°, while the deepest penetration occurred at an incident angle of 45° except for the welded 410 (75°). In addition, erosion mechanism of all the specimens showed a mixed ductile and brittle morphology.
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Tsai, Feng-tse, and 蔡豐澤. "Effect of Aluminum Content on the Mechanical Properties of AISI 410 Stainless Steel." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/19939575539913861105.
Full textAbstract:
碩士國立雲林科技大學
機械工程系碩士班
95
This study investigates the effect of aluminum content on the mechanical properties of AISI 410 stainless steel at different solution temperature(850℃-1000℃). The microstructure, including metallography, grain size, retained austenite, fracture surface of impact and tensile specimens, size and kinds of precipitates were conducted. The mechanical properties, including tensile stress, yield stress, hardness, impact energy, elongation and reduction area were measured. It was found that tensile stress, yield stress and hardness increase with increasing solution temperature due to the increase of hardenability and dissolution of carbides. Furthermore, impact energy, elongation and reduction area decrease with increasing solution temperature. It was found that tensile stress, yield stress and impact energy decrease with increasing aluminum content due to the increase of prior austenite grain size. The grain size of the specimens content 0.022wt% and 0.037wt% were almost twice as coarse as that of the specimen containing 0.013wt% aluminum after solution treatment at 1000℃. It is postulated that aluminum nitride precipitates become coarse in the steel containing more aluminum.
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Tsai, Ming-Chin, and 蔡明欽. "Microstructural Evolution of Simulated Heat-Affected Zone in Cr-Mo Alloy Steels and Phase Transformation in an AISI 410 Stainless Steel." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/30755497447113132587.
Full textAbstract:
博士國立臺灣大學
材料科學與工程學研究所
90
The Cr-Mo series alloy steel possesses many advantages: such as good creep resistance, easy formation, good weld-ability and good corrosion resistance. Thus this type of steel is extensively used in power generation industry for containment vessels, superheater tubes and steam pipes. Components of steam pipes are usually used in the temperature range 500-600℃, with the service stresses of about 15-30 MPa. Hence, creep rupture is the major ultimate failure mechanism during service. Considerable research has been devoted to the assessment of creep life by extrapolating the results of short-term laboratory creep tests to long-term services. However, such parametric techniques usually assume the microstructure remains unchange even during the extended service. In fact, the microstructure changes with time when exposed to high temperature and high pressures, especially in the heat-affected zone (HAZ) of a weld material. In this work, simulated HAZ experiments with heat inputs of 20, 50 and 80 kJ/cm were carried out for Cr-Mo alloy steel plates (include 2.25Cr-1Mo steel and modified 2.25Cr-1Mo steel). The thermal cycles used corresponded to the actual thermal cycles that occur in the coarse grained region of the real HAZ. The simulated HAZ samples were then heated at 700℃ for different time intervals ranging form 1 to 500h. The corresponding metallographs and transmission electron micrographs for the high temperature long-term exposed samples have been investigated. The result shows that the bainitic structure is more stable than the martensitic structure, i.e. the steel with a bainite structure is suitable to be used in high temperatures. In this study, the carbide precipitation sequence is proposed as follows: ε-carbide→ M3C→ M7C3→ M23C6. The M23C6 carbide was found to be the final stable carbide after a long period of tempering, when the recrystallization occurred. In this tempering condition during service, the safety of the Cr-Mo steel should receive special attention. Furthermore, it is very important to consider the effect of cooling rate on the martensitic transformation in the Cr-Mo alloy steels. The different cooling rate would result in the different microstructures and Ms temperature. According to the experiment data, the Ms temperature increases with cooling rate decreasing. While the Ms temperature decrease with the increase of austenization temperature. The mechanism of micro-twin and retained austenite forming had been explained using crystallographic study. The formation of micro-twin is due to mechanical accommodation; that of retained austenite results from the mechanical stabilization. These two microstructures had been investigated deeply in this thesis. At the last parts of this thesis, phase transformations in an AISI 410 steel and in a modified 9Cr-1Mo steel during continuous cooling or isothermal treatment are reported. Dilatometry and electron micrography have been employed. The results provided strong evidences on the existence of retained austenite films and micro-twins in lath martensite structure, and that the coalesced lath in tempered martensite regions depends on the local crystal orientation relationship. The reason why no bainitic structure can be obtained in these two steels has also been elucidated.
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Hello and 景勝男. "The Study of Thermally Grown Oxide Films Prevent AISI 410 Stainless Steel from Corrosion." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/87885144823092230947.
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