Academic literature on the topic 'Quenching; Tempering; Hardness'
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Journal articles on the topic "Quenching; Tempering; Hardness"
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Tang, Guo Zhang, Yun Gang Li, He Yang, Yu Zhu Zhang, and Hai Li Yang. "Optimization on Heat Treatment Process of 45CrMnSi Steel by Orthogonal Test." Advanced Materials Research 393-395 (November 2011): 217–21. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.217.
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The effect of quenching temperature, tempering temperature and tempering time on hardness of 45CrMnSi steel was studied by orthogonal test. It was found that the order of significant factors for the hardness was quenching temperature > tempering temperature > tempering time. Based on the results of the range analysis, the optimum process parameters for the maximum hardness were that the quenching temperature was 900°C, the tempering temperature was 150°C, and the tempering time was 180 min. Under the optimum process conditions, the hardness reached to HRC52 with impact toughness of 15 J/cm2. The hardness and toughness met the need of the comprehensive mechanical property and proper toughness of 45CrMnSi.
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Dai, Yu Mei, Yong Qing Ma, Yan Bin Wu, and Ya Nan Ji. "A Study on the Microstructure and Hardness Feature of 6CrW2MoVSi Steel after Heat Treatment." Advanced Materials Research 887-888 (February 2014): 223–27. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.223.
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6CrW2MoVSi steel has a refined and even microstructure after heat treatment, the average size of annealing carbide is 0.6 μm; quenching martensite is mainly lath-shaped martensite and only a small amount of acicular martensite, and the size of quenching acicular at 950 °C is smaller than 2.5 μm. The curve of quenching hardness increasing with quenching temperature rising is divided into three sections. In the middle section of quenching between 910 °C ~ 980 °C, quenching hardness presents slow rising trend. After higher temperature quenching, there are low and high temperature tempering precipitation hardening zones. At 220 °C ~ 240 °C tempering temperature, precipitation hardness is HRC54 ~ 58. At 540 °C ~ 570 °C tempering temperature, precipitation hardness is HRC52 ~ 56.
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Li, Hong Bo, Jing Wang, Han Chi Cheng, Chun Jie Li, and Xing Jun Su. "Effect of Tempering Temperature on Mechanical Properties of High Strength Wear Resistant Cast Steel." Advanced Materials Research 791-793 (September 2013): 440–43. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.440.
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This paper mainly studied the high temperature quenching oil quenching, tempering temperature on the influence of high strength steel mechanical properties of wear resistant. The results show that high strength and toughness wear-resistant cast steel with 880°C× 30min after oil quenching, the hardness of 38.6HRC steel, the impact toughness value reaches 40.18J/cm2. After 200°C, 400°C and 600°C tempering, with the increase of the tempering temperature, the hardness decreased linearly, as by 600°C tempering, the hardness has been reduced to 22.3HRC. Impact toughness with the tempering temperature, the overall upward trend, the impact toughness of some reduced at 400°C, the highest impact toughness value reaches 113.34J/cm2. From the fracture morphology can be seen, with the increase of tempering temperature, ductile fracture increased, by 600°C tempering is dimple fracture, obviously can not see the traces of brittle fracture.
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Ma, Yong Qing, Xiao Jing Zhang, Yu Fen Liang, and Guo Fang Liu. "A Study on Austenite Catalytic Cryogenic Treatment of Cr-W-Mo-V High Alloy Medium-Upper Carbon Steel." Advanced Materials Research 936 (June 2014): 1173–78. http://dx.doi.org/10.4028/www.scientific.net/amr.936.1173.
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The processing of austenite catalytic cryogenic treatment of two components of Cr-W-Mo-V high alloy medium-upper carbon steels and the effect on the retained austenite transformation and tempering hardness were studied in this paper. The results show that, the effect of austenite catalytic cryogenic treatment of Cr-W-Mo-V high alloy medium-upper carbon steel is better than that of direct cryogenic treatment after quenching, and the content of residual austenite reduced to below 5%, and the hardness improved by 1.5HRC than that of conventional quenching and tempering. The retained austenite catalytic temperature of Cr-W-Mo-V high alloy medium-upper carbon steel merely is higher than 10°C~20°C of the temperature for the highest tempering hardness. Catalytic temperature Tc can be determined by experimental method of conventional quenching and tempering of the steel, in which the microstructure feature is precipitation of M3C carbide particle of 0.01μm~0.03μm in martensite matrix, and the content of retained austenite decreases evidently. By cryogenic treatment after the austenite catalyzed the retained austenite of quenching are transformed into more martensite, and in the subsequent tempering processing the original quenching martensite and the martensite from retained austenite transformation almost will form synchronous precipitation hardening. Thus the tempering hardness improves evidently as well.
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Li, Hong Bo, Han Chi Cheng, Jing Wang, Chun Jie Li, and Xing Jun Su. "Influence of Tempering Temperature on Microstructure and Mechanical Properties of 35CrMnSiMo Cast Steel." Advanced Materials Research 791-793 (September 2013): 431–34. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.431.
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The tempering temperature on microstructure and mechanical properties of 35CrMnSiMo cast steel are studies in this article. Results showed that 880°C×30min 35CrMnSiMo cast steel after quenching water, hardness up to 49.6HRC, reached 39.04 J/cm2 toughness. Tempering temperature selected 200°C, 400°C and 600°C, respectively with the increase of the tempering temperature plummeting hardness and impact toughness are on the rise, but at 400°Cdecreased. Photos can be seen from your organization after quenching, which contains a lot of lath martensite, a small amount of lump some residual austenite and martensite, 200°C tempering martensite has been reduced, some of carbide precipitation into tempered martensite. Tempering of martensite quenching slats or flake, it is made of flake martensite and small ξ carbide distribution.
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Wu, Meng, Yan Ping Zeng, and Wen Yang. "Effect of Heat Treatment on the Microstructure and Hardness f X38CrMo16 Steel." Applied Mechanics and Materials 455 (November 2013): 179–84. http://dx.doi.org/10.4028/www.scientific.net/amm.455.179.
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Effect of quenching-tempering process on microstructure and hardness of X38CrMo16 steel was investigated by means of OM, SEM, XRD and a digital hardness tester. The quenched and tempered steel consists of martensite (or its tempered structure), δ-ferrite and secondary particles. The secondary particles are identified as a FeCr intermetallic phase based on EDS and XRD analysis. Along with the increase of quenching temperature, the quantity of secondary particles gradually decreases and the prior austenite grains grow significantly, which led to the coarsening of martensite. A large number of blocky ferrite formed due to the increase of chromium level in the matrix. In addition, the hardness of the quenched steel continuously increases with quenching temperature up to 1100°C and then drop observably. Hence, the suitable quenching temperature of the steel is between 1050 and 1100°C. After tempering at 200 and 300°C, the hardness of the steel decreased due to the formation of tempered martensite and increased slightly after tempering at 400°C owing to secondary hardening, whereas this value decreased again after tempering at 500 and 600°C due to the formation of tempered sorbite.
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Ma, Yong Qing, Yu Mei Dai, Yu Fen Liang, and Xiao Jing Zhang. "Temper-Resistance of Cr-W-Mo-V High Carbon Medium Alloy Steel and its Hardness Forecast." Advanced Materials Research 503-504 (April 2012): 591–96. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.591.
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The temper-resistance temperature of Cr-W-Mo-V high carbon medium alloy steels is in a range at 200°C-300°C. Along with increasing C and alloy contents in particular Cr content of the steels, the temper-resistance is boost up gradually and maximal hardness arrives to 63-64HRC at temperature 200°C-250°C. When budget for quenching matrix composition and undissolved carbides, the actual quenching temperature TH is corresponding to the calculational temperature TC by phase-equilibrium thermodynamics as TH=TC + (1000°C－TC)/6.5, and roughly, the calculational temperature is less 20°C than actual temperature when quenching at 800°C-890°C. The carbides precipitation during tempering is agreement with phase equilibrium thermodynamic calculation incompletely, thereinto (Fe,Cr)3C carbide precipitation is leading at 200°C-250°C.The higher hardness at temper-resistance temperature is corresponding to tempering temperature of remnant austenitic decomposing acutely.The tempering hardness can be estimated on the basis of quenching hardness calculation. The quenching hardness value can be obtained from HC=α（1+β）/(0.00915α+0.00527), in which α is the square root of carbon content in the matrix and β is correction coefficient of solid solution strengthening.
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Zheng, Hua, Kai Ming Wu, S. F. Sun, and G. W. Hu. "Niobium-Alloyed Steel Treated by Quenching-Partitioning-Tempering." Applied Mechanics and Materials 528 (February 2014): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amm.528.149.
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Given the strong recent interest in quenching-partitioning-tempering processed steels, the Niobium-alloyed medium carbon steel was investigated here. The microstructural observations and hardness were analyzed by optical microscope, transmission electron microscope, X-ray diffraction and hardness test. Results show that when quenched at 210°C and partitioned at 450°C, the quenching partitioning-tempering process leads to ultra fine-grained microstructures of martensite, retained austenite and carbides. And the microstructure and hardness changed differently with the increase of partitioned time.
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Zeng, Yan Ping, and Wen Yang. "Effect of Heat Treatment on the Microstructure and Hardness of a Newly Developed Plastic Injection Mold Steel." Applied Mechanics and Materials 302 (February 2013): 263–68. http://dx.doi.org/10.4028/www.scientific.net/amm.302.263.
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The microstructure of a new plastic injection mold steel in the annealed condition and effect of quenching-tempering process on the microstructure and hardness of this steel were investigated by means of OM, SEM, XRD and a digital hardness tester. The microstructure of the annealed steel consisted of ferrite and secondary particles which were identified as a FeCr intermetallic phase based on EDS and XRD analysis. Strong segregation exists in the steel. The microstructures of the quenched steels consisted of fine martensite, a small amount of blocky ferrite and secondary particles except quenching at 1150°C, where the microstructures of the quenched steels consisted of coarse martensite and large number of blocky ferrite. The segregation occurring in the annealed steel can be eliminated completely after heat treatment at the temperatures above 1050°C for 30min. The hardness of the quenched steel continuously increases with quenching temperature up to 1100°C and then drop observably. Hence, the suitable quenching temperature of the steel lies between 1050 and 1100°C. After tempering at 200 and 300°C, the hardness of the steel decreased due to the formation of tempered martensite and increased slightly after tempering at 400 and 500°C owing to secondary hardening, whereas this value decreased markedly after tempering at 600°C due to the formation of tempered sorbite. The amount of secondary particles gradually increased with tempering temperature.
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Ma, Yong Qing, Hong Tao Gao, Yu Fen Liang, and Xiao Jing Zhang. "Secondary Hardening during Tempering of Cr-W-Mo-V High Alloy Medium-Upper Carbon Steel and its Hardness Forecast." Advanced Materials Research 415-417 (December 2011): 813–18. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.813.
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Along with increasing W and Mo contents in Cr-W-Mo-V high alloy medium-upper carbon steels, the maximal hardness of secondary hardening during tempering is increasing gradually and arrives to 66.8HRC, and the congruent quenching temperature and the tempering temperature corresponding to maximal hardness are ascending. The quenching microstructure of experimental steels is matrix and a small quantity of undissolved carbides when the hardness is maximal, wich is corresponding to tempering temperature of remnant austenitic decomposing acutely. The precipitation of M6C and MC carbides was detected, and M7C3 and M3C carbides was detected too. But M23C6 carbide did not appear and M2C carbide was detected undistinguishably. The temperature range of tempering maximal hardness is 500°C-550°C, and an exact temperature is opposite to the mass fraction ratio of equilibrium carbide phases at the temperature. The tempering hardness value can be obtained from HS= a(1+b)/(0.0127a+0.00297), in which a is square root of saturation level of the carbon in the matrix and b is correction factor having something to do with alloy elements of carbide precipitation.
Dissertations / Theses on the topic "Quenching; Tempering; Hardness"
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Zemui, Simon. "Quenching and tempering hardness response of front axle steel beams : Different material properties during quenching and tempering." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62747.
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The aim of this thesis was to investigate what the relation is between as-quench hardness and final surface hardness for steel beams is, depending on what tempering temperature is used. Also explain how chemistry, dimension and microstructure effects the final mechanical properties of the front axle beam. For this a review of literature concerning the effects was completed.Hardness measurement on the surface was performed on the ends of the beam (bottom and top). This hardness measurement was performed on 6 different front axle articles of the same material (41CrS4) and 2 different front axle articles of another material (40CrMo4). The relation diagram gives an estimation of what type of tempering temperature is needed to achieve the final hardness that is desired. Because the relation was done with some inconsistences it can’t be said to give a perfect answer. The relation diagrams only work for material 41CrS4 and 40CrMo4. For the core hardness test, 2 articles of 41CrS4 and one article of 40CrMo4 was measured on 5 different position on the cross-section, the beams for the respective articles were taken from quenched state and quenched+tempered. The beam dimensions have a significant effect when it comes to cooling down the part and achieve as close to uniform hardness as possible. Even though the Middle point of the I-section sample is one of the closest cores to the surface, it has a softer core compared with the other cores. While there exists hardness difference after quenching between different points in the core they even out after tempering. When comparing the core hardness with the surface hardness it can be said that the surface hardness is not as hard as the core because of decarburization. The microstructure analysis was done on 2 articles of 41CrS4 and one article of 40CrMo4. Samples from the 3 articles is taken from both the as-quenched state and quenched+tempered state. From the optical microscope it could be seen, that the surface of the beams decarbonizes leading to a higher amount of ferrite at the structure and softer surface. Because of this 15 mm into the material is harder than at-surface. Decarburization of the 41CrS4 steels made it so that what should have been a martensite and bainite dominated surface became a ferrite and bainite dominated.To decide the actual amount of retained austenite in the sample an XRD-analysis was performed. The XRD-analysis is done only for one article type of 41CrS4. From the front axle beam three samples of three different locations (bottom, middle, top) was taken for the analysis. For the theoretical calculation of the retained austenite vs the actual amount it can be said that is a very good representation of the total amount of retained austenite in the product. But the theoretical calculation deviates a bit from the actual amount at the top part of the beam.<br>Syftet med denna avhandling var att undersöka vad relationen är mellan härdat ythårdhet och slut ythårdhet för stålbalkar är, beroende på vilken anlöpnings temperatur som används. Tar också upp hur kemi, dimension och mikrostruktur påverkar de sista mekaniska egenskaperna hos framaxel balken. För detta genomfördes en genomgång av litteraturen om effekterna.Hårdhetsmätning på ytan utfördes på balkens ändar (botten och toppen). Denna hårdhetsmätning utfördes på 6 olika främre axelartiklar av samma material (41CrS4) och 2 olika främre axelartiklar av annat material (40CrMo4). Relationsdiagrammet ger en uppskattning av vilken typ av anlöpningstemperatur som behövs för att uppnå den slutliga hårdheten som önskas. Eftersom förhållandet gjordes med vissa inkonsekvenser kan det inte sägas ge ett perfekt svar. Relationsdiagrammen fungerar endast för material 41CrS4 och 40CrMo4.För kärnhårdhetstestet mättes 2 artiklar av 41CrS4 och en artikel av 40CrMo4 i 5 olika positioner på tvärsnittet, stålen för respektive artiklar togs från härdat tillstånd och härdat + anlöpt. Dimensionerna har en signifikant effekt när det gäller att kyla ner delen och uppnå så nära enhetlig hårdhet som möjligt. Även om mittpunkten i I-sektionsprovet är en av de närmaste kärnorna till ytan, så har det en mjukare kärna jämfört med de andra kärnorna. Det finns hårdhetsskillnad efter härdning mellan de olika punkter men de jämnar ut sig efter anlöpningen. När man jämför kärnhårdheten med ythårdheten kan man säga att ythårdheten inte är så hård på grund av avkolning.Mikrostrukturanalysen gjordes på 2 artiklar av 41CrS4 och en artikel av 40CrMo4. Prover från de 3 artiklarna tas från både härdat tillstånd och härdat + anlöpt tillstånd. Från det optiska mikroskopet kunde man se att stålbalkens yta har blivit utsatt för avkolning vilket leder till en högre mängd ferrit vid strukturen och en mjukare yta. På grund av detta, så är 15 mm in i materialet hårare än vid ytan. Avkolning av 41CrS4 stål gjorde så att det som borde ha varit ett martensit och bainit dominerat yta blev istället ferrit och bainit dominerat.XRD-analysen görs endast för en artikelart av 41CrS4. Från fram axelbalken togs tre prov från tre olika platser (botten, mitten, toppen) för analysen. För att bestämma den verkliga mängden restaustenit i provet utfördes en XRD-analys. För den teoretiska beräkningen av den rest austeniten jämfört med det faktiska beloppet kan man säga det är en mycket bra representation av den totala mängden kvarhållen austenit i produkten. Men den teoretiska beräkningen avviker lite från den faktiska mängden vid stålens övre del.
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Li, Yu. "Effect of aluminium and vanadium on the microstructure and properties of microalloyed steels." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366804.
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Pytlíčková, Kateřina. "Vliv struktury a tepelného zpracování na vlastnosti ložiskových ocelí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228091.
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Heat treatment influences structure and characteristics of treatmented material. Good heat treatment of steels for bearings ensures hardness of matrix 60 - 65 HRC, whereas structure has be formed by tempered fine needle-shaped martensite with definite part of residual austenite. Carbides should be evenly dispersed, they mustn´t create carbide network and carbide lines. Quality of steels for bearings is also influenced by volume and morphology of inclusions in the matrix. In this diploma thesis various conditions of heat treatment were to be set up with the aim of choose the optimal ones. These ensures perfect martensite transformation and full hardening of all component. Quenching from 760 °C – 770 °C was quite unsatisfactory. At this temperature resulting structure was ferritic-perlitic, because martensite transformation did not pass. Too long hold on hardening temperature also had unfavourable influence on resulting structure and characteristics. In this case, structure was created by very coarse needle-shaped martensite. Coarsening of martensite needle locally exceeded maximum allowed level. In the structure there was also possible to watch partly soluted globular carbides. Optimal heat treatment is quenching from 850 °C – 870 °C followed by tempering at 220 °C. Resulting structure quite agree with above-mentioned needs. This heat treatment can be recommended for technical practise.
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Tobolík, Stanislav. "Tepelné zpracování nástrojových ocelí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254221.
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This thesis deals with the properties of ledeburitic chrome-vanadium tool steel after heat treatment. Theoretical part contains charakterization of ledeburitic steels, the posibility of manufacturing and heat treatment. There are also briefly describes the principles of the test methods, which were used. The practical part is focused on describing the results of 12 sample groups, with different heat treatment. The results are compared in the final discussion.
Book chapters on the topic "Quenching; Tempering; Hardness"
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Wierszyłłowski, Ignacy. "The Influence of Post-Quenching Deep Cryogenic Treatment on Tempering Processes and Properties of D2 Tool Steel. Studies of Structure, XRD, Dilatometry, Hardness and Fracture Toughness." In Defect and Diffusion Forum. Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908451-36-1.415.
Full textConference papers on the topic "Quenching; Tempering; Hardness"
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Shi, Jing, and C. Richard Liu. "Developing Complete Prediction Capability for Thermal Damages in Finish Machining of a Hardened Steel." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79261.
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The material thermal damages in hard turning can be classified as re-tempering and re-quenching, and the capability of predicting both damages is critical to obtaining optimal machining parameters for best part service performance. In this study, thermal damages were represented by material hardness change, and models for re-quenching and re-tempering were constructed through heat treatment experiments. The model for re-tempering describes hardness change based on material thermal history, while the re-quenching model defines material hardness as a function of material quenching temperature. In the meantime, a valid finite element (FE) model was adopted to calculate the material temperature histories in 3D hard turning. The obtained thermal histories were fed into the damage models, and thus the distributions of thermal damages beneath machined surfaces could be predicted.
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Patra Karmakar, Debapriya, Muvvala Gopinath, and Ashish Kumar Nath. "Effect of Tempering Temperature on Hardness and Microstructure of Laser Surface Remelted AISI H13 Tool Steel." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-3014.
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Surface hardening was performed by laser surface remelting of AISI H13 tool steel samples using a high power fiber laser. The surface hardened samples were exposed to different tempering temperature of 500°C, 700 °C and 900 °C in a furnace for one hour and brought back to room temperature in still air and by water quenching. Changes of the laser remelted and hardened layer were investigated in terms of microstructure and hardness before and after exposure to different tempering temperatures. Laser remelting caused mainly dendritic microstructure at the top layer but the dendritic structure of the remelted layer got altered after tempering at high temperatures. Air and water quenching caused almost similar result during tempering of laser remelted layer. The microhardness variations along depth after tempering at different temperatures indicates that the surface hardening imparted by laser remelting remains almost intact up to 700 °C but gets destroyed at 900 °C. Although the experimental temperature limits gives approximate threshold values, but it provides a clear indication of a safe limit for laser surface hardened components in high temperature applications like hot-forging dies and friction stir welding tool, etc.
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Farè, Stefano, Emanuele Paravicini Bagliani, Stefano Crippa, Fabio Zana, and Philippe Darcis. "Heavy Wall Bends for Sour and Arctic-Alike Environment." In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-42053.
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During last decade, customers’ requirements of Line Pipes and accessories became more and more stringent. This process is led by the exploitation of fields with more severe conditions of pressure, environment and temperature. For this reason, heavy wall products (both straight pipes and bends) need to be developed. A development program was carried out in order to satisfy more stringent requirements and higher wall thickness. The metallurgical approach to steel design aimed to improve the combination of strength and toughness and increase the control of hardness after quenching and tempering, preserving adequate weldability. Industrial trials were performed to manufacture 60 mm thick hot induction bends in grade X65. Characterization was carried out after various post bending heat treatments (quenching, tempering and post welding). The new low-C steel showed promising results. The full characterization of off-line Q&T bends at various locations (tangent length, transition zone, and bend body) confirmed the achievement of X65 grade, with hardness HV10 < 240, Charpy V-notch transition temperature < −60°C, Crack Tip Opening Displacement > 0.7 mm at −45 °C, and very good HIC and SSC resistance.
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Mannucci, Aldo, Ettore Anelli, Fabio Zana, et al. "Bends for Critical Line Pipe Projects: Advantages of the Off-Line Full Quenching and Tempering." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79800.
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Recent trends for linepipe projects reflect a sustained increasing complexity: Sour Service (SS), High Temperature & High Pressure (HT/HP) field conditions, deep and ultra-deep water oil and gas transportation, Artic and Artic “alike” areas. This reflects into stringent requirements for manufacturing and testing of the concerned products, which are not only the straight pipes but also a number of accessories, among which bends are the ones presenting the most complex combination of critical issues. As long as a whole chain reliability standpoint is assumed as the main concern, the design, production and supply of the bends have become a key stage within a linepipe project. Bends for linepipe projects are produced in general by hot induction bending (HIB). Two different fabrication routes can be clearly identified: HIB followed by Stress Relieving (SR) and HIB followed by off-line full quenching and tempering (Q&T). The first method is known as “Traditional route (TR)”, while the second one as “Quenching-Tank (QT)”. A large investigation program was carried out involving the most recognised benders in Europe. The matrix of industrial trials comprised a dimensional size range from 168 to 406 mm OD, 8 to 34 mm WT; X60 to X70 steel grades, different bending and post-bending heat treatments conditions and mother pipe chemistries. For each analysed item, the final bend, the corresponding mother pipe and samples taken in as-bent / as-quenched (TR / QT) conditions were fully characterised in terms of mechanical properties, hardness profiles and microstructure features. As a result, a much better performance was found for the bends produced by the off-line full Q&T method, principally due to the better quenching efficiency with respect to the in-line system. Production of bends through out the traditional method can be seen as a reliable option for bends which are not going to face hard conditions in the field, and therefore the corresponding specification requirements are no stringent as well (i.e. X52 grade or lower, Charpy tests required at 0°C or higher temperature, no corrosion tests required, etc.). If either stringent conditions are required or X60-X80 steel grades are involved, the off-line quenching tank route becomes the reliable option.
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Orazi, Leonardo, Alessandro Fortunato, Giovanni Tani, Giampaolo Campana, Alessandro Ascari, and Gabriele Cuccolini. "A New Computationally Efficient Method in Laser Hardening Modeling." In ASME 2008 International Manufacturing Science and Engineering Conference collocated with the 3rd JSME/ASME International Conference on Materials and Processing. ASMEDC, 2008. http://dx.doi.org/10.1115/msec_icmp2008-72501.
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Laser hardening is a laser assisted process devoted to the surface hardening of the mechanical components. This process is highly suitable for medium carbon steels with carbon content comprised between 0.2 – 0.6% or for low alloy steels which are usually surface hardened during their manufacturing process. Laser hardening technology is gaining a great industrial interest in the last years in fact, the possibility of integrating the heating source directly on the production line, together with the absence of the quenching medium, meets the production needs of modern industries. Laser hardening optimization could be complex especially when tempering due to multiple passes effects must be considered. Many research studies have been proposed in the last years aimed at predicting the optimal laser process parameters such as beam power density, beam velocity and scanning strategies. Many Authors agree with the assumption that the whole austenite resulting from the heating is transformed into martensite during the quenching. This is a valid approximation for single pass but could be a rough hypothesis in multiple-passes when the cooling rate could be not so high. Moreover hysteresis phenomena, due to the severe heat cycle occurring in laser hardening, should be taken into account for pearlite to austenite and martensite to austenite transformations during heating and for martensite tempering during multiple passes. In this paper the crucial problems to be faced regarding laser surface hardening modeling are discussed with respect to current literature. In particular, partial austenitization of the pearlite is suggested as a solution of the hardness prediction of the profile depth. Then three transformation parameters are proposed in order to take into account the hysteresis phenomena in martensite and pearlite transformations into austenite and in martensite tempering. Finally several experimental examples are proposed in order to validate the mentioned assumptions.
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Yang, Mei, Yishu Zhang, Haoxing You, Richard Smith, and Richard D. Sisson. "Hardening of Selective Laser Melted M2 Steel." In HT2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.ht2021p0007.
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Abstract Selective laser melting (SLM) is an additive manufacturing technique that can be used to make the near-net-shape metal parts. M2 is a high-speed steel widely used in cutting tools, which is due to its high hardness of this steel. Conventionally, the hardening heat treatment process, including quenching and tempering, is conducted to achieve the high hardness for M2 wrought parts. It was debated if the hardening is needed for additively manufactured M2 parts. In the present work, the M2 steel part is fabricated by SLM. It is found that the hardness of as-fabricated M2 SLM parts is much lower than the hardened M2 wrought parts. The characterization was conducted including X-ray diffraction (XRD), optical microscopy, Scanning Electron Microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) to investigate the microstructure evolution of as-fabricated, quenched, and tempered M2 SLM part. The M2 wrought part was heat-treated simultaneously with the SLM part for comparison. It was found the hardness of M2 SLM part after heat treatment is increased and comparable to the wrought part. Both quenched and tempered M2 SLM and wrought parts have the same microstructure, while the size of the carbides in the wrought part is larger than that in the SLM part.
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Okada, Masato, Shin Terada, Yuki Kataoka, Takeshi Kihara, Takuya Miura, and Masaaki Otsu. "Burnishing Characteristics of Sliding Burnishing Process With Active Rotary Tool Targeting Stainless Steel." In JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/lemp2020-8515.
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Abstract This paper investigates the burnishing characteristics of a developed sliding burnishing method with active rotary tool targeting a martensitic stainless steel. Two types of martensitic stainless steel, annealing (AN) stainless steel and quenching and tempering (QT) stainless steel, were targeted. The burnishing characteristics evaluated included surface roughness, profile, microstructure, subsurface hardness, bending property, and corrosion resistance. A sufficiently smooth surface, approximately Ra = 0.1 μm and Ra = 0.025 μm in both materials, respectively, was obtained using the developed burnishing method; irregular profile smoothing occurred due to the material flow of the subsurface. The subsurface hardness increased at a depth of 40 μm or more when using the developed burnishing method on the AN material, but no effect was observed for the QT material. Moreover, the bending yield point and strength of the sheet shape workpiece increased by applying the burnishing process to the AN material. The influence of the burnishing process on the bending properties was also observed for the QT material. Corrosion resistance can be improved through the burnishing process.
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Ortolani, Matteo, Ettore Anelli, Paolo Novelli, and Emanuele Paravicini Bagliani. "Sour Resistant High Strength Seamless Pipes for Risers." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10252.
Full textAbstract:
In case of a Weld On Connector’s riser using ASTM A182 F22 forged joints, high strength (SMYS of 80 ksi) steel pipes for sour service (hardness below or equal to 250 HV10) suitable for welding to the connectors are required. Welding is challenging because of the Post Weld Heat Treatment (PWHT) needed to reduce the hardness in the F22 HAZ while maintaining the required strength in the pipe. Theoretical evaluations were performed by means of metallurgical models and a potential solution was identified in grade P22-like steel (2¼ Cr - 1 Mo), with minor modifications with respect to the standard ASTM A335 and supplied in Q&T condition. A trial heat was cast and hot-rolled into pipes. After water quenching, the response to tempering was assessed by means of laboratory heat treatments and subsequent mechanical testing, together with metallurgical examination. Simulated PWHTs were also performed on Q&T material. 80 ksi grade P22 seamless pipes were finally produced and qualification involved mechanical testing before and after simulated PWHT: SMYS of 80 ksi and HV10 ≤ 250 requirements were met. The material also exhibited excellent toughness and resistance to HIC and SSC cracking.
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Koripelli, Rama S., and David N. French. "Issues Related to Creep-Strength-Enhanced Ferritic (CSEF) Steels." In ASME 2014 Power Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/power2014-32027.
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T-91 and P-91 are the oldest of a new class of creep-strength-enhanced ferritic steels (CSEF) approved for use in boilers and pressure vessels. These newer alloys develop high strength through heat treatment, a rapid cooling or quenching to form martensite, followed by a temper to improve ductility. As a result, these alloys offer a much higher allowable stress which means thinner sections provide adequate strength for high-temperature service. Most of the applications thus far have been a substitute for P-22/T-22. The primary advantages of T91 materials over conventional low-alloy steels are: higher allowable stresses for a given temperature, improved oxidation, corrosion, creep and fatigue resistance. T23 is also considered as a member of the family of CSEF steels. The alloying elements such as tungsten, vanadium, boron, titanium and niobium and heat treatment separate this alloy from the well defined T22 steel. Although, T23 is designated for tubing application, its piping counterpart P23 has a strong potential in header applications due to superior strength compared to P22 headers. Now that T-91 and P-91 have been in service for nearly 30 years, some shortcomings have become apparent. A perusal of the allowable stress values for T-91 shows a drop off in tensile strength above about 1150°F. Thus, start-up conditions where superheaters, and especially reheaters, may experience metal temperatures above 1200°F, lead to over-tempering and loss of creep strength. During welding, the temperature varies from above the melting point of the steel to room temperature. The heat-affected zone (HAZ) is defined as the zone next to the fusion line at the edge of the weld metal that has been heated high enough to form austenite, i.e., above the lower critical transformation temperature. On cooling, the austenite transforms to martensite. Next to this region of microstructural transformation, there is an area heated to just below the austenite formation temperature, but above the tempering temperature of the tube/pipe when manufactured. This region has been, in effect, over-tempered by the welding and subsequent post-weld heat treatment (PWHT). Over-tempering softens the tempered martensite with the associated loss of both tensile and creep strength. This region of low strength is subject to failure during service. Creep strength of T91 steel is obtained via a quenching process followed by controlled tempering treatment. Elements such as niobium and vanadium in the steel precipitate at defect sites as carbides; this is known as the ‘pinning effect’. Any subsequent welding/cold working requires a precise PWHT. Inappropriate and/or lack of PWHT can destroy the ‘pinning effect’ resulting in loss of creep strength and premature failures. Several case studies will be presented with the problems associated with T91/T23 materials. Case studies will be presented, with the results of optical microscopy, scanning electron microscopy, hardness measurements and energy dispersive spectroscopy analysis. One case study will discuss how the over-tempering caused a reduced creep strength, resulting in premature creep failure in a finishing superheater tube. A second case presents the carburization of a heat recovery steam generator (HRSG) superheater tube, resulting in reduced corrosion/oxidation resistance. A case study demonstrates how a short-term overheating excursion led to reheat cracking in T23 tubing. Another case will present creep degradation in T91 reheater steel tube due to high temperature exposures (over-tempering).
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Arai, Yuji, Kunio Kondo, Hiroyuki Hirata, et al. "Metallurgical Design of Newly Developed Material for Seamless Pipes of X80–X100 Grades." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29183.
Full textAbstract:
With the increasing development of oil and gas fields in deepwater or ultra-deepwater with deep well depth, the development of high strength seamless pipe has become necessary. This paper describes a metallurgical design of seamless pipe with high strength reaching X80–X100 grade (minimum yield strength, 552 MPa–689 MPa) manufactured by steel containing very low carbon and with a microstructure of uniform bainite. The effect of microstructure of quenched and tempered (QT) steel on strength and toughness is investigated in laboratory. Uniform bainitic structure without coarse martensite-austenite constituent (M-A) is obtained by lowering bainite transformation temperature during quenching process by controlling the alloying elements. Moreover the structure is very effective in obtaining good toughness for tempered steel even with the high strength X100 grade. Sufficiently low hardness and good toughness in heat affected zone (HAZ) are confirmed by welding tests. The trial production of developed steel is conducted by applying inline QT process in medium-size seamless mill according to an alloying design obtained in laboratory tests. The seamless pipes of the trial production achieve grades X80 to X100 by changing tempering temperature. Some data of mechanical properties of the produced pipes is introduced.