Academic literature on the topic 'Ferrite percentage'
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Journal articles on the topic "Ferrite percentage"
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Jonit, Siti Soleha, Madzlan Aziz, and Rita Sundari. "FESEM-EDX and CV Characteristics of Dopant (Mn, Co, Ni) Magnesium Ferrites." Advanced Materials Research 645 (January 2013): 150–53. http://dx.doi.org/10.4028/www.scientific.net/amr.645.150.
Full textAbstract:
Doping magnesium ferrites (MgFe2 O4) with Mn, Co and Ni, which were synthesized by sol gel method using citric acid and polyvinyl alcohol (P VA) and calcined at 500oC, showed interesting electrochemical featur es based on their cyclic voltammetric (CV) characteristics using 5 µL ferrite – poly vinylidene fluoride in ethano l deposited on a screen printed carbon electrode (SPCE) in a mixture of 1.0 M KOH and ferricyanide solution recorded with a scan rate of 0.02 Vs -1. The Mn doped magnesium ferrite (x = 0.9) showed the most remarkable CV performance over other doped element (Co and Ni) and un-doped magnesiu m ferrites. The surface morphology of doped ferrites was studied by applying a field emissi on scanning electron microscope (FESEM) in conjunction with an energy dispersive X-ray spect roscopy (EDX) analysis. The results revealed that Mn posed the highest percentage on the surface ( ≈ 21.5 %), followed by Co (≈ 19.5%) and Ni ( ≈ 6.7%) with respect to x = 0.9 of M0.9Mg0.1Fe 2 O4 (M = Co, Mn and Ni) at 500oC calcination. The study showed the possibility of yielding semi conducting ferrites using own fabricated magnesium ferrite and its metal doping.
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Pathak, T. K., N. H. Vasoya, Thillai Sivakumar Natarajan, Kunal B. Modi, and Rajesh J. Tayade. "Photocatalytic Degradation of Aqueous Nitrobenzene Solution Using Nanocrystalline Mg-Mn Ferrites." Materials Science Forum 764 (July 2013): 116–29. http://dx.doi.org/10.4028/www.scientific.net/msf.764.116.
Full textAbstract:
MgxMn1-xFe2O4(x = 0.0, 0.2, 0.4, 0.5, 0.6 0.8 and 1.0) spinel ferrite system was synthesized by the chemical co-precipitation route. Subsequent characterization of synthesized Mg-Mn ferrites was carried out by X-ray powder diffraction and transmission electron microscopy to study the structural and textural properties of photocatalysts. Porosity, surface area and equivalent surface free energy of different Mg-Mn ferrite photocatalysts were calculated. The photocatalytic activity of synthesized photocatalysts was evaluated by degradation of nitrobenzene in aqueous medium under ultraviolet light irradiation. The results demonstrated that the percentage degradation of nitrobenzene was decreased with increase in Mg concentration (x) from x = 0.0 0.5 and further increase in concentration from x = 0.6 1.0 results increase in percentage degradation of NB. This dissimilarity in the percentage degradation of NB may be due to the change in grain morphology, optical energy band gap, role played by d-electrons and porosity as a function of Mg-substitution for Mn2+in the system. The percentage degradation was further confirmed by chemical oxygen demand (COD) analysis.
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Sun, Ying. "Research of the DWTT Fracture of X70 Pipeline Steel." Advanced Materials Research 535-537 (June 2012): 643–46. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.643.
Full textAbstract:
The DWTT fracture toughness of X70 pipeline steel with different content and grain size of polygonal ferrite was investigated. The results show that when the content of polygon ferrite is above 28%, the shear-area percentage of DWTT fracture begins to decrease instead of increase, while polygonal ferrite toughening effect weakens. It is the difference of the polygonal ferrite content that results in the difference of shear-area percentage of DWTT fracture.
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Li, Jun Ru, Xiao Hang Sun, Yan Ji, et al. "Effects of Austenitizing Temperature and Cooling Rate on the Mechanical Properties of 36MnVS4 Steel for Automobile Engine Connecting Rod." Materials Science Forum 898 (June 2017): 1195–201. http://dx.doi.org/10.4028/www.scientific.net/msf.898.1195.
Full textAbstract:
The relationship between microstructure and mechanical properties of 36MnVS4 steel was studied. Different prior austenite grain sizes were obtained by austenitizing at 850, 950 and 1050 °C, respectively, and different ferrite contents were obtained by different cooling rates. Austenitizing temperature mainly influenced the grain size. With the austenitizing temperature increasing, grain size increased and the phase transformation starting temperature increased. Also, the strength increased and the plasticity and toughness decreased. Cooling rate mainly influenced the microstructure percentage. With the cooling rate increasing, ferrite percentage decreased and pearlite percentage increased. And meanwhile, the strength increased and ductility and toughness decreased. Microstructure had a significant influence on fracture splitting properties. With the grain size increasing, fracture splitting properties were markedly improved. With the ferrite percentage increasing and pearlite percentage decreasing, fracture splitting properties were worsened.
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Darwish, Moustafa A., Alex V. Trukhanov, Oleg S. Senatov, et al. "Investigation of AC-Measurements of Epoxy/Ferrite Composites." Nanomaterials 10, no. 3 (2020): 492. http://dx.doi.org/10.3390/nano10030492.
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A pure ferrite and epoxy samples as well as the epoxy/ferrite composites with different 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.% weight ferrite contents have been prepared by the chemical co-precipitation method. AC-conductivity and dielectric properties such as the dielectric constant and dielectric loss of the prepared samples have been studied. The obtained results showed that the samples had a semiconductor behavior. The dielectric constant of the composites has been calculated theoretically using several models. For the composite sample that contains 20 wt.% of ferrites, these models give satisfactory compliance, while for the composite samples with a higher percentage of nanofillers, more than 30 wt.% theoretical results do not coincide with experimental data. The investigated polymer has very low conductivity, so this type of polymer can be useful for high-frequency applications, which can reduce the losses caused by eddy current. Thus, the prepared samples are promising materials for practical use as elements of microwave devices.
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Abdullahi, Umma. "Effects of Alloying Element and Heat Treatment on Mechanical Properties of Alloy Steels." International Journal of Engineering Materials and Manufacture 8, no. 3 (2023): 67–74. http://dx.doi.org/10.26776/ijemm.08.03.2023.02.
Full textAbstract:
The effects of Cr and Ni on three different types of steel with different carbon ratios under constant conditions such as the welding current 120A, voltage 80V, Diameter 10 mm and angle 60 degree was observed. Nickel percentage of up to 0.147% and Chromium 0.083% contributed to affecting the mechanical properties of the steel. Undissolved carbide particles refine the austenite grain size. In the presence of nickel, chromium carbide is less effective in austenite grain refinement than chromium carbide in absence of nickel at temperature below 975°C. Nickel does not produce any austenite grain refinement but presence of nickel promotes the formation of acicular ferrites. It was also found that Ni and Cr as chromium carbide also refines the ferrite grain size and morphology. Cr as chromium carbide is more effective in refining ferrite grain size than nickel. The microstructure of the base metal as a reference material was analysed before heating to support the results of chemical analysis. Nickel percentage of up to 0.147% and Chromium 0.083%. Molybdenum was 0.03% which contributed to affecting the mechanical properties of the steel.Keyword: Alloy steel, Heat treatment, Chromium, Nickel, Grain size
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Kolhar, Priyanka, Basavaraja Sannakki, Meenakshi Verma, Siddaramappa Suresha, Mansoor Alshehri, and Nehad Ali Shah. "Investigation of Structural, Dielectric and Optical Properties of Polyaniline—Magnesium Ferrite Composites." Nanomaterials 13, no. 15 (2023): 2234. http://dx.doi.org/10.3390/nano13152234.
Full textAbstract:
A study on the influence of magnesium ferrite nanoparticles on the optical and dielectric attributes of Polyaniline has been conducted. Magnesium nano Ferrite powder is synthesized by the self-propagating solution combustion method. Polyaniline–Magnesium nano ferrite composites are synthesized by chemical oxidative polymerization of aniline with the addition of Magnesium nanoparticles. The samples are characterized with XRD and UV-Vis spectrometer, in the wavelength range of 200–800 nm and studied for optical properties. Dielectric properties are studied in the frequency range of 50 Hz to 5 MHz. X-ray diffraction reveals single phase formation of Magnesium ferrite, whereas Polyaniline shows an amorphous nature. In the XRD of the composites, we see the crystalline peaks of ferrite becoming more intense with the addition of ferrite and whereas the peak of Polyaniline diminishes. The crystallite size is quantified with the Debye—Scherrer formula, and it increases as the content of ferrite in the composites increases. The micro-strain decreases in the composites as the percentage of ferrite enhances in the composites. In the UV-Vis absorption spectra of composites, the peaks of Polyaniline shift to higher wavelength and there is also an absorption band in the spectra of composites corresponding to that of Magnesium ferrite particles. Both direct and indirect band gaps are calculated with the Tauc plot, and both the optical band gap decrease as the percentage of ferrite increases in the composite. The dielectric loss and dielectric constant both decrease with frequency in all the samples, and the dielectric response are in good agreement with Maxwell—Wagner model. Ferrite—polymer composites with both conducting and magnetic properties are considered useful for electromagnetic shielding and microwave absorption.
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Surekha, Pinninti, Paul Douglas Sanasi, and Majji Ravi Kumar. "One-Pot Synthesis of Substituted Pyridine." Nanoscale Reports 5, no. 2 (2022): 4–6. https://doi.org/10.26524/nr.5.5.
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The studies on application of magnetically separable substituted nano ferrites towards the multicomponent one-pot synthesis of heterocyclic compounds were thoroughly investigated. The present study gives an efficient method for the one-pot three-component synthesis of poly substituted pyridine derivatives by the cyclo-condensation of aromaticaldehyde, malononitrile and substituted phenols in the presence of magnetically recoverable nano copper ferrite catalyst. This method involve simproved advantages like low percentage of catalyst used, lesser reaction times, higher yields ,magnetic recoverability and reuse of the catalyst, which makes it an environmentally benign process.
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Tran Van, Chinh, Anh Nguyen Tuan, Phuong Nguyen Thi Hoai, et al. "Study on the synthesis of porphyrin-modified copper ferrite as photocatalyst for treatment of mb organic dye in aqueous media." Vietnam Journal of Catalysis and Adsorption 9, no. 3 (2020): 107–11. http://dx.doi.org/10.51316/jca.2020.058.
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This work aims to modify the copper ferrite with a porphyrin derivatives by a simple method of self-assembly. The resultant porphyrin-modified copper ferrite was utilized as a photocatalyst for the removal of methyl blue dyes (MB) from aqueous solution. The results showed that the porphyrin nanofibers were well-intergrated with the copper ferrite nanoparticles. The porphyrin-modified copper ferrite materials exhibited the high photocatalytic performance toward MB dye with the removal percentage of approximately 100% after 200 minutes of irradiation under simulated light. The catalyst could be facilely separate by using a external magnet and reused.
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Chen, Yu, Xiang Dong Liu, and Li Hui Wang. "Research on the Microstructure and Properties for Nb-Contained Cold-Rolling High Strength Steel Sheet." Advanced Materials Research 602-604 (December 2012): 488–91. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.488.
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The high strength high plasticity high beneficial textile cold-rolling steel with 540MPa tensile strength 27% elongation 1.67 (111) textile index is developed in industry. The experimental results show that the ferrite fine grain around 5μm supports the properties of both high strength and plasticity, while the ferrite with percentage more than 90% leads to high elongation, and the large number second precipitation phase NbC with uniform fine size around 10nm is helpful to fine ferrite grain and form strong（111）textile fiber.
Dissertations / Theses on the topic "Ferrite percentage"
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Las-casas, Marina Spyer. "Modelagem utilizando redes neurais artificiais para predição da percentagem de ferrita e parâmetros geométricos de cordões de solda de aços inoxidáveis austeníticos." Universidade Federal de Minas Gerais, 2013. http://hdl.handle.net/1843/BUOS-9ABGGH.
Full textAbstract:
A model was developed based on experimental data obtained under laboratory conditions. To acquire these data we used an industrial robot that made welds with GMAW (Gas Metal Arc Welding) process. Welds were made with different values of voltage, current and filler material while all others parameters were kept constant. The following austenitic stainless steel wires were used: ER 308LSi ER, ER 309LSi and ER 312. All weld beads were performed on AISI 304 plates. The input parameters of the network are Vweld (input parameter that determines the robot welding voltage), Aweld (input parameter that determines the robot welding current) and values of Nickel and Chromium equivalent of wires calculated using the Schaeffler formula. The quantity of ferrite was analyzed by magnetic methods calibrated according to the AWS standard procedure and therefore will be adopted the term "Ferrite Number" (FN) in place of percent ferrite to identify this variable. In addition to FN, the model predicts the width, reinforcement and penetration of the weld beads.<br>Esse trabalho investiga um modelo matemático que não exige grande recurso computacional e que define com boa precisão alguns parâmetros de saída mais importantes de uma solda de aços inoxidáveis austeníticos realizada com o processo de soldagem GMA. Os parâmetros de saída considerados mais importantes são a quantidade de ferrita e as medidas de largura, penetração e reforço do cordão de solda. Apesar de uma grande quantidade de fatores influenciarem os parâmetros de saída que se desejam encontrar, foram selecionados três fatores com maior influência para variar. São eles: a tensão, corrente e material do arame. Ou seja, esse modelo pretende avaliar o comportamento para soldas realizadas com diferentes metais de base e de adição. O modelo matemático apresentado se baseia em redes neurais artificiais e duas redes serão apresentadas. A primeira usa como dados de entrada os valores de tensão, corrente e material de adição e como dados de saída a quantidade de ferrita, largura, penetração e reforço do cordão, enquanto a segunda usa a quantidade de ferrita, largura, penetração e reforço do cordão como dado de entrada e tensão, corrente e material de adição como dados de saída. Essa segunda rede poderá ser utilizada pelo operador para programar o robô de acordo com os requisitos desejados para a solda.
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Pisa, Pedro Terrence. "Associations between biological alcohol consumption markers, reported alcohol intakes, and biological health outcomes in an African population in transition / Pedro T. Pisa." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2325.
Full textBooks on the topic "Ferrite percentage"
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Macdougall, Iain C. Iron management in renal anaemia. Edited by David J. Goldsmith. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199592548.003.0126.
Full textAbstract:
Although erythropoiesis-stimulating agent therapy is the mainstay of renal anaemia management, maintenance of an adequate iron supply to the bone marrow is also pivotal in the process of erythropoiesis. Thus, it is important to be able to detect iron insufficiency, and to treat this appropriately. Iron deficiency may be absolute (when the total body iron stores are exhausted) or functional (when the total body iron stores are normal or increased, but there is an inability to release iron from the stores rapidly enough to provide a ready supply of iron to the bone marrow). Several markers of iron status have been tested, but those of the greatest utility are the serum ferritin, transferrin saturation, and percentage of hypochromic red cells. Measurement of serum hepcidin, which is the master regulator of iron homoeostasis, has to date proved disappointing as a means of detecting iron insufficiency, and none of the available iron markers reliably exclude the need for supplemental iron. Iron may be replaced by either the oral or the intravenous route. In the advanced stages of chronic kidney disease, however, hepcidin is upregulated, and this powerfully inhibits the absorption of iron from the gut. Thus, such patients often require intravenous iron, particularly those on dialysis. Several intravenous (IV) iron preparations are available, and they have in common a core containing an iron salt, surrounded by a carbohydrate shell. The IV iron preparations differ in their kinetics of iron release from the iron–carbohydrate complex. In recent times, several new IV iron preparations have become available, and these allow a greater amount of iron to be given more rapidly as a single administration, without the need for a test dose.
Book chapters on the topic "Ferrite percentage"
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Sumalatha, Edapalli, Dachepalli Ravinder, Nyathani Maramu, et al. "Crystal Chemistry, Rietveld Analysis, Structural and Electrical Properties of Cobalt-Erbium Nano-Ferrites." In Ferrite [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98864.
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Synthesis of Cobalt-Erbium nano-ferrites with formulation CoErxFe2-xO4 (x = 0, 0.005, 0.010, 0.015, 0.020, 0.025, and 0.030) using technique of citrate-gel auto-combustion was done. Characterization of prepared powders was done by using XRD, EDAX, FESEM, AFM and FTIR Spectroscopy, DC resistivity properties respectively. XRD Rietveld Analysis, SEM, TEM and EDAX analysis were taken up in studying spectral, structural, magnetic and electrical properties. XRD pattern of CEF nano particles confirm single phase cubic spinal structure. The structural variables given by lattice constant (a), lattice volume (v), average crystallite size (D) and X-ray density(dx), Bulk density (d), porosity (p), percentage of pore space (P%), surface area (s), strain (ε), dislocation density (δ), along with ionic radii, bond length and hoping length were calculated. SEM and TEM results reveal homogeneous nature of particles accompanied by clusters having no impurity pickup. TEM analysis gives information about particle size of nanocrystalline ferrite while EDAX analysis confirm elemental composition. Emergence of two arch shaped frequency bands (ν1 and ν2) that represent vibrations at tetrahedral site (A) and octahedral site(B) was indicated by spectra of FTIR. The samples electrical resistivity (DC) was measured between 30°C -600°C with Two probe method. XRD Rietveld analysis confirm crystallite size lying between 20.84 nm–14.40 nm while SEM analysis indicate formation of agglomerates and TEM analysis indicate particle size ranging between 24 nm–16 nm. DC Electrical measurements indicate continuous decrease in resistivity with increasing temperature while increasing doping decreases curie temperature. The Magnetic parameters such as Saturation magnetization (Ms), Remanent magnetization (Mr), Coercivity (Hc) and Squareness ratio (R = Mr/Ms), Magnetic moment (nB) were altered by doping of Er+3 content in the increasing order (x = 0.00 to 0.030). The increasing erbium content decreases magnetization thus converting the sample into soft magnetic material. Observations indicated strong dependence of magnetic properties on Erbium substitution and coercivity varies in accordance with anisotropy constant. Due to the presence of magnetic dipole Erbium substituted cobalt ferrites can be used in electromagnetic applications. The present study investigates the effect of different compositions of Er3+ replaced for Fe on structural properties and electrical resistivity of cobalt ferrites.
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Ram, Nanak, and Vijay Gautam. "Experimental Studies of Microstructure and Its Effect on Mechanical Properties of As-Cast Si-Mo-Cr Ductile Cast Iron." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220809.
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In the present work, three heats of Si-Mo-Cr ductile cast iron with varying amounts of major alloying elements are produced. The effect of the microstructural features on the microhardness, tensile strength and ductility is studied. Increasing the nodule count decreases the pearlite-ferrite ratio, which results in a decrease in tensile strength but an increase in percentage elongation. The spherical nodule plays a significant role in arresting the crack and reorients the crack path around the nodule, as evident from the results of scanning electron microscopy.
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Adnan Islam, Rashed. "Enhancement of the Magnetoelectric Effect in PZT-Ni Ferrite Composites Using Post Sintering Thermal Treatment." In Ferrites - Synthesis and Applications. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99870.
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In this chapter, the piezoelectric and magnetoelectric properties of Pb (Zr0.52T0.48)O3–X NiFe1.9Mn0.1O4 (PZT-NFM, where X ranges from 3 to 10%) were investigated along with SEM and TEM analysis. Post sintering thermal treatment (annealing and aging) was introduced to enhance the piezoelectric and magnetoelectric property of the composites. The density was found around 7.6–7.8 gm/cc. The piezoelectric constant d33 and the voltage constant were found to be decreased with increasing magnetic particle from 3–10%. Experimental results indicated that the magnetoelectric voltage coefficient (dE/dH) increases with increasing percentage of Nickel Ferrite (~35 for 3% NF to 140 mV/Oe. cm for 10% NF at 1125°C). The samples, which were annealed and aged after sintering show as high as 50% (140 to 220 mV/cm Oe) increase in dE/dH coefficient. This is due to the increase in resistivity due to better homogeneity. The H-M curve of the composite powders show that the PZT-NFM is a ferromagnetic material as well. The SEM investigation shows very compact structure with average grain size around 150 nm and some areas of the NF rich phase. The X-ray mapping shows that the NF is distributed in the big grains of the matrix and after annealing it homogenizes.
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Whitworth, Brian. "Spam as a Symptom of Electronic Communication Technologies that Ignore Social Requirements." In E-Collaboration. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-652-5.ch107.
Full textAbstract:
Spam, undesired and usually unsolicited e-mail, has been a growing problem for some time. A 2003 Sunbelt Software poll found spam (or junk mail) has surpassed viruses as the number-one unwanted network intrusion (Townsend & Taphouse, 2003). Time magazine reports that for major e-mail providers, 40 to 70% of all incoming mail is deleted at the server (Taylor, 2003), and AOL reports that 80% of its inbound e-mail, 1.5 to 1.9 billion messages a day, is spam the company blocks. Spam is the e-mail consumer’s number-one complaint (Davidson, 2003). Despite Internet service provider (ISP) filtering, up to 30% of in-box messages are spam. While each of us may only take seconds (or minutes) to deal with such mail, over billions of cases the losses are significant. A Ferris Research report estimates spam 2003 costs for U.S. companies at $10 billion (Bekker, 2003). While improved filters send more spam to trash cans, ever more spam is sent, consuming an increasing proportion of network resources. Users shielded behind spam filters may notice little change, but the Internet transmitted-spam percentage has been steadily growing. It was 8% in 2001, grew from 20% to 40% in 6 months over 2002 to 2003, and continues to grow (Weiss, 2003). In May 2003, the amount of spam e-mail exceeded nonspam for the first time, that is, over 50% of transmitted e-mail is now spam (Vaughan-Nichols, 2003). Informal estimates for 2004 are over 60%, with some as high as 80%. In practical terms, an ISP needing one server for customers must buy another just for spam almost no one reads. This cost passes on to users in increased connection fees. Pretransmission filtering could reduce this waste, but creates another problem: spam false positives, that is, valid e-mail filtered as spam. If you accidentally use spam words, like enlarge, your e-mail may be filtered. Currently, receivers can recover false rejects from their spam filter’s quarantine area, but filtering before transmission means the message never arrives at all, so neither sender nor receiver knows there is an error. Imagine if the postal mail system shredded unwanted mail and lost mail in the process. People could lose confidence that the mail will get through. If a communication environment cannot be trusted, confidence in it can collapse. Electronic communication systems sit on the horns of a dilemma. Reducing spam increases delivery failure rate, while guaranteeing delivery increases spam rates. Either way, by social failure of confidence or technical failure of capability, spam threatens the transmission system itself (Weinstein, 2003). As the percentage of transmitted spam increases, both problems increase. If spam were 99% of sent mail, a small false-positive percentage becomes a much higher percentage of valid e-mail that failed. The growing spam problem is recognized ambivalently by IT writers who espouse new Bayesian spam filters but note, “The problem with spam is that it is almost impossible to define” (Vaughan-Nichols, 2003, p. 142), or who advocate legal solutions but say none have worked so far. The technical community seems to be in a state of denial regarding spam. Despite some successes, transmitted spam is increasing. Moral outrage, spam blockers, spamming the spammers, black and white lists, and legal responses have slowed but not stopped it. Spam blockers, by hiding the problem from users, may be making it worse, as a Band-Aid covers but does not cure a systemic sore. Asking for a technical tool to stop spam may be asking the wrong question. If spam is a social problem, it may require a social solution, which in cyberspace means technical support for social requirements (Whitworth & Whitworth, 2004).
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Whitworth, Brian. "Spam as a Symptom of Electronic Communication Technologies that Ignore Social Requirements." In Encyclopedia of Human Computer Interaction. IGI Global, 2006. http://dx.doi.org/10.4018/978-1-59140-562-7.ch083.
Full textAbstract:
Spam, undesired and usually unsolicited e-mail, has been a growing problem for some time. A 2003 Sunbelt Software poll found spam (or junk mail) has surpassed viruses as the number-one unwanted network intrusion (Townsend & Taphouse, 2003). Time magazine reports that for major e-mail providers, 40 to 70% of all incoming mail is deleted at the server (Taylor, 2003), and AOL reports that 80% of its inbound e-mail, 1.5 to 1.9 billion messages a day, is spam the company blocks. Spam is the e-mail consumer’s number-one complaint (Davidson, 2003). Despite Internet service provider (ISP) filtering, up to 30% of in-box messages are spam. While each of us may only take seconds (or minutes) to deal with such mail, over billions of cases the losses are significant. A Ferris Research report estimates spam 2003 costs for U.S. companies at $10 billion (Bekker, 2003). While improved filters send more spam to trash cans, ever more spam is sent, consuming an increasing proportion of network resources. Users shielded behind spam filters may notice little change, but the Internet transmitted-spam percentage has been steadily growing. It was 8% in 2001, grew from 20% to 40% in 6 months over 2002 to 2003, and continues to grow (Weiss, 2003). In May 2003, the amount of spam e-mail exceeded nonspam for the first time, that is, over 50% of transmitted e-mail is now spam (Vaughan-Nichols, 2003). Informal estimates for 2004 are over 60%, with some as high as 80%. In practical terms, an ISP needing one server for customers must buy another just for spam almost no one reads. This cost passes on to users in increased connection fees. Pretransmission filtering could reduce this waste, but creates another problem: spam false positives, that is, valid e-mail filtered as spam. If you accidentally use spam words, like enlarge, your e-mail may be filtered. Currently, receivers can recover false rejects from their spam filter’s quarantine area, but filtering before transmission means the message never arrives at all, so neither sender nor receiver knows there is an error. Imagine if the postal mail system shredded unwanted mail and lost mail in the process. People could lose confidence that the mail will get through. If a communication environment cannot be trusted, confidence in it can collapse. Electronic communication systems sit on the horns of a dilemma. Reducing spam increases delivery failure rate, while guaranteeing delivery increases spam rates. Either way, by social failure of confidence or technical failure of capability, spam threatens the transmission system itself (Weinstein, 2003). As the percentage of transmitted spam increases, both problems increase. If spam were 99% of sent mail, a small false-positive percentage becomes a much higher percentage of valid e-mail that failed. The growing spam problem is recognized ambivalently by IT writers who espouse new Bayesian spam filters but note, “The problem with spam is that it is almost impossible to define” (Vaughan-Nichols, 2003, p. 142), or who advocate legal solutions but say none have worked so far. The technical community seems to be in a state of denial regarding spam. Despite some successes, transmitted spam is increasing. Moral outrage, spam blockers, spamming the spammers, black and white lists, and legal responses have slowed but not stopped it. Spam blockers, by hiding the problem from users, may be making it worse, as a Band-Aid covers but does not cure a systemic sore. Asking for a technical tool to stop spam may be asking the wrong question. If spam is a social problem, it may require a social solution, which in cyberspace means technical support for social requirements (Whitworth & Whitworth, 2004).
Conference papers on the topic "Ferrite percentage"
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Sadek, A. Z., and A. M. El-Sheikh. "Failure Analysis of SS 304 Weldments by Metallurgically Enhanced Stress Corrosion Cracking in Laboratory Environments." In CORROSION 2000. NACE International, 2000. https://doi.org/10.5006/c2000-00365.
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Abstract The mechanisms of metallurgically enhanced crack initiation and propagation in austenitic stainless steel weldments were investigated using electrochemical and physical methods. The test media was boiling Magnesium Chloride solutions, MgCl2, at 32% and 37% weight respectively. A batch of U-Bend specimens was tested at each salt concentration. Optical and electron microscopy was used to examine cracked weldments. Traditionally, welding rods used for joining austenitic stainless steels contain a percentage of retained δ-ferrite. This small content of the electrically active phase remains trapped between interdendritic arms of the austenitic matrix after solidification. Such a situation leads to the formation of numerous microgalvanic cell systems in the electrolytic test media. It was found from optical and electron microscopy results that δ-ferrite rich interdendritic spaces suffered excessive preferential dissolution in favor of austenitic dendrites. It was also found that initiated cracks propagated along interdendritic spaces suitably aligned with respect to the stress field. Electrochemical test results indicate that weldments tend to corrode along the borderline between activity and passivity. The results further suggest that weldments exhibited repetitive cycles of passive film formation and dissolution.
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Echaniz, G., C. Morales, and T. Pérez. "The Effect of Microstructure on the KISSC Low Alloy Carbon Steels." In CORROSION 1998. NACE International, 1998. https://doi.org/10.5006/c1998-98120.
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Abstract In this work, the effect of microstructure of low alloy carbon steels on the resistance to sulfide stress cracking (SSC) was analyzed. Several modified AISI 4130 steels (most of them microalloyed with V, Nb, Ti or B) were heat treated so different yield strengths and microstructures were obtained. The SSC performance was evaluated using Double-Cantilever-Beam Test (Method D NACE TM0177-96). According with their microstructure, the materials can be divided in three different types: materials that presented some percentage of upper bainite in their microstructure (composed of laths of approximately 1 micron wide and large carbides at the border of the laths) presented significantly lower SSC resistance. Materials which had microstructure composed mainly of tempered lath martensite had an intermediate resistance. In addition, the presence of large grain boundaries reduced the SSC resistance. The best resistance was obtained with a microstructure that is a mixed of tempered lath martensite and a phase composed of ferrite and carbides; this material presented also a fine dispersion of (CN)Nb.
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Borenstein, S. W., and D. C. White. "Influence of Welding Variables on Microbiologically Influenced Corrosion of Austenitic Stainless Steel, Weldments." In CORROSION 1989. NACE International, 1989. https://doi.org/10.5006/c1989-89183.
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Abstract Biofilms develop on metallic surfaces in contact with natural waters. Biofilms can contain microorganisms which accelerate corrosion. The chemical composition and microstructure of weldments, as produced by welding processes and heat treatment, can influence the degree of accelerated corrosion. It may be possible to avoid costly pitting failures if the weldment could be less susceptible to microbiologically influenced corrosion (MIC) by proper selection of filler metal, welding process variables, or heat treatment. Field testing and subsequent laboratory electrochemical analyses were conducted to examine the role of welding and heat treatment variables on MIC of austenitic stainless steel weldments. Pipe specimens were fabricated (GTAW) of both 304L and 316L for field testing. Filler metals were selected to produce three percentages of ferrite content (low, medium, and high). Weldments of each ferrite content were evaluated in both as- deposited and solution-annealed conditions. Field testing involved exposure of the weld specimens for approximately one year to a small trickle of water directly from a well known to produce MIC. Mounds indicating biomass formation appeared on the welds after two weeks, exposure. Laboratory electrochemical analyses involved measurements of corrosion potentials as a function of time and critical pitting potentials for weld and base metal samples in microbial solutions.
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Patel, Ritesh, Hardik Shah, and Jimmy Dutt. "Evaluation of Mechanical and Corrosion Properties of Base Metal and HAZ Having ASS 304L Forgings Containing Ferrite." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21254.
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Abstract Austenitic Stainless Steel type 304L is being widely used for fabrication due to excellent corrosion resistance and good weldability. Ferrite (3–10%) is needed in weld metal to prevent hot cracking during welding, however, base metal should preferably not contain any ferrite. It is observed that thick forged SS304L components may have small percentage of ferrite depending on the chemical composition, forging parameters including intermediate soaking cycle and final solution annealing heat treatment cycle. Little study or information is available on effect of ferrite in base metal on weld/Heat Affected Zone (HAZ) properties. Present study is aimed to evaluate mechanical and corrosion properties of weldment produced with base metal containing 2–4% of ferrite. Forged tubes with two different levels of delta ferrite, with &lt; 0.5% & 2–4%, were welded to Plates with &lt; 0.5% delta ferrite using Mechanized Gas Tungsten Arc Welding (GTAW) process with Inner Bore Welding Technique. Tensile test, Impact test and Hardness test were performed on base metal & HAZ in as-welded condition for both the cases. Microstructure examination in HAZ and Intergranular Corrosion (IGC) test were also performed for both the cases. Results of mechanical tests, microstructure examination and IGC test have been compared between base metal/HAZ of &lt; 0.5% and 2–4% Ferrite base metal. No significant difference has been observed in test result of tubes with 2–4% delta ferrite as compared to tubes with &lt; 0.5% delta ferrite.
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Pourkia, Navid, Pirooz Marashi, Rouzbeh Leylabi, Seyed Alireza Tabatabaei, and Hadi Torshizi. "The Effect of Weld Metal Manganese Content on the Microstructure, Mechanical Properties and Hot Crack Susceptibility of Helically Welded Linepipes." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64152.
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The effect of manganese addition on decreasing hot crack susceptibility of submerged arc welding in microalloyed steels is well understood, but its increment should not cause unsuitable changes in metallurgical and mechanical properties of weld metal. Therefore, since weld metal Mn content in SAW process is mainly controlled by welding wire composition, the aim of this investigation is to study the effect of wire Mn content on the microstructure, mechanical properties and hot crack susceptibility of helical linepipes weld metal. In this regard, three different wires with 0.88, 1.05 and 1.54 wt% of Mn content were selected and welding was performed in both experimental and production process condition of X70 helical linepipes. As a result, 1.26, 1.44 and 1.67 wt% of Mn in weld metal was obtained respectively. Metallographical examinations using optical and scanning electron microscopy showed that, increasing the amount of Mn in weld metal, decrease the grain size of all phases (acicular ferrite, primary ferrite and ferrite with aligned second phase). Moreover, in the expense of increasing acicular ferrite, the volume fraction of primary ferrite (mostly grain boundary ferrite) and ferrite with aligned second phase decreased. Also, the results of mechanical properties indicated that the higher the amount of Mn, the higher the strength and hardness of weld metal, but in the case of impact toughness and tensile elongation, an optimum level was observed and lower toughness in the highest Mn content weld metal is attributed to the increasing hardenability and thus formation of martensite/retained austenite islands and grain boundary carbides in coincident sites of acicular ferrite grains. Moreover, analyzes in more than 1000m helical linepipes weld metal length showed that increasing weld metal Mn content up to 1.4wt%, reduced the possibility of hot crack formation from total percentage of 0.005 to around 0.001.
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Zhang, Xiaoli, Chuanjing Zhuang, Lingkang Ji, et al. "The Micro Structural Characteristic Parameters of High Grade Pipeline Steel and its Mechanical Properties." In 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10256.
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The microstructure of high grade pipeline steels, including X65, X70, X80, X100, were studied by SEM and EBSD, respectively. It was found that the microstructures of high grade pipeline steels were composed of lower bainite, granular bainite and acicular ferrite. The phases of kinds of pipeline steels were composed of Fe3C, retained austenite and ferrite. And their percentage content, grain size and its distribution were studied respectively also. These micro structural parameters were correlated to the mechanical properties of kinds of pipeline steels. Furthermore, all kinds of angles of grain boundaries were studied, and the relationship between the angles of grain boundaries and mechanical properties was obtained. It was shown that as the improving of the steel grade, the grain boundary including small angle and large angle increased. And only when grain boundary was greater than 15 degree, it was effective to the toughness behavior.
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Subramanian, S. V., and J. M. Gray. "Design and Processing of Niobium Microalloyed Cost Effective Line Pipe Steel With Enhanced Strength and Fracture Toughness." In ASME 2013 India Oil and Gas Pipeline Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/iogpc2013-9829.
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The functional role of niobium in the original HTP X-80 design of high niobium (0.1wt%), low interstitial ( C 0.03 to 0.04, N<0.005wt%) cost-effective base chemistry is (i) to use Zener drag from strain induced precipitation of NbC during thermo-mechanical rolling and solute drag from solute niobium to retard static recrystallization, (ii) to impart adequate rolling reduction below temperature of no recrystallization to promote large strain accumulation in pancaked austenite, and (iii) to promote fine ferrite grain size by strain induced phase transformation under accelerated cooling conditions, thereby obtain high strength and fracture toughness at low temperature through grain size effect. Residual niobium in austenite is used to impart additional strength through transformation hardening, dislocation hardening from accelerated cooling and precipitation strengthening of ferrite through accelerated cooling and interrupted cooling at coiling temperature. Recent research has confirmed the importance of control of density and dispersion of crystallographic high angle boundaries which are superimposed on the morphological microstructure in order to prevent the initiation of brittle fracture. Extensive research has been carried out in HTP base chemistry to determine the processing options to control the density and dispersion of high angle boundaries to produce higher grade (>X-80) line pipe steels with enhanced fracture toughness. Whereas the resistance to ductile fracture is measured by Charpy toughness, the resistance to brittle fracture is inferred from ductile to brittle transition temperature and percentage shear in DWTT. The research has underscored the importance of austenite grain refinement in upstream processing of HTP before pancaking in finish rolling to control density and dispersion of high angle boundaries in order to prevent brittle fracture initiation. Experimental results are presented which demonstrate that HTP base chemistry is a cost effective design to produce higher grade line pipe steels, not only to achieve high resistance to ductile and brittle fracture in the base plate, but also in HAZ regions associated with relatively high heat input welding in weld fabrication of pipes from plates, and Girth field welding of pipes involving low heat input multi-pass welding.
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Ro, Yun-Jo, Seung-Hwan Chon, Jang-Yong Yoo, and Ki-Bong Kang. "Development of Offshore X65/70 Steels for Deep Water Application." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90211.
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Heavy gauge X65/70 steels have been developed for deep-water offshore application. As the thickness of linepipe steels is increased, Mo, Ni, V alloying elements are generally employed to improve the low temperature toughness and strength balance. However, the price of such alloying element has been rapidly increased. Hence, in the present work, a lean composition is designed to achieve thick X65/70 grade steels with better strength and toughness balance. To prevent the degradation of toughness or strength due to a lean alloying composition, the authors optimize processing parameters, such as a rolling stop temperature or accelerated cooling patterns. By in large, two strategies have been applied to develop linepipe steels; i) cooling starts in γ + α region, and iii) rolling stops in γ + α region. These strategies promote ferrite+bainite dual phase microstructures exhibiting a good low temperature toughness and strength balance. Such dual phase microstructures are characterized by using EBSD (electron back scattered diffraction) technique. The result shows a percentage of DWTT shear area is strongly correlated with effective grain size (misorientation ≥ 15°). As a result, the present work demonstrates that heavy gauge API steels grade X65/70 can be achieved with Mo+V free or small addition of Mo alloying elements.
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McNamara, J. D., A. J. Duncan, M. J. Morgan, and P. S. Korinko. "Imaging Hydrogen in Stainless Steel Alloys by Kelvin Probe Force Microscopy." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84755.
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Kelvin probe force microscopy (KPFM) was used to image austenitic stainless steel (SS) samples (Type 304L) fabricated by the laser engineered net shaping (LENS®) process. The samples were hydrogen charged (H-charged) and subsequently cut and polished. The surface contact potential difference (CPD) of the samples was measured using the KPFM technique, a form of atomic force microscopy. A set of uncharged samples was also studied for reference and changes in the CPD were on the noise level. For H-charged samples fabricated by the LENS® process, the resulting surface potential images show a change in CPD of about 10 – 20mV around cell-like boundaries (5–10 μm in size) and grain boundaries (50–100 μm in size). The significant change in the CPD is affected by variation of the local work function, which indicates the presence of hydrogen. The elemental composition of the LENS® samples was studied using energy dispersive spectroscopy (EDS) which showed an increase in the atomic percentage of Cr and a decrease in Ni around the cell-like boundaries. The existence of intercellular ferrite on the sub-grain boundaries may explain the propensity of hydrogen to segregate around these regions. The finer grain structure of LENS® samples compared to that of forged or welded samples suggests that the hydrogen can be dispersed differently throughout this material than in traditionally forged austenitic SS. This study is conducted to elucidate the behavior of hydrogen with respect to the microstructure of additively manufactured stainless steel alloys.
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Kirk, Mark, and Marjorie Erickson. "Assessment of the Temperature Dependence of Ferritic Steel Fracture Toughness on or Near the Lower Shelf." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45850.
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Within the American Society of Mechanical Engineers (ASME) the Section XI Working Group on Flaw Evaluation (WGFE) is currently working to develop a revision to Code Case N-830. This revision incorporates a complete and self-consistent suite of models that describe completely the temperature dependence, scatter, and interdependencies between all the fracture metrics (i.e., KJc, KIa, JIc, J0.1, and J-R) from the lower shelf through the upper shelf. A paper presented at the 2014 ASME Pressure Vessel and Piping Conference described most of these models; a companion paper at this conference describes the J-R model. This paper also supports the WGFE effort by performing an assessment of the appropriateness of Wallin’s Master Curve model to represent toughness data on the lower shelf, and by comparing the Master Curve with the current Code KIc curve on the lower shelf. The work presented in this paper supports the following conclusions: 1. The Master Curve provides a reasonable representation of cleavage fracture toughness (KJc) data at lower shelf temperatures. A statistical evaluation of a large database demonstrates that the Master Curve works well to temperatures approximately 140 °C below To or, equivalently, approximately 160 °C below RTTo. 2. The percentile of cleavage fracture toughness data falling below a KIc curve indexed to RTTo varies considerably with temperature. At lower shelf temperatures as much as half of the data lie below the KIc curve, while at temperatures close to RTTo this percentage falls to approximately ≈ 1.5%. The current guidance of Nonmandatory Appendix A to Section XI to use structural factors of √10 or √2 is one means of addressing this inconsistency. 3. The inconsistent degree to which the KIc curve, with or without structural factors, bounds fracture toughness data cannot be fixed within the current Code framework for two reasons: the KIc curve does not reflect the actual temperature dependence shown by the fracture toughness of ferritic RPV steels, and the ratio of a mean or median toughness curve to a fixed percentile bound is not a constant value. It is for these reasons that in the next revision of Code Case N-830 the ASME WGFE is moving away from use of the KIc curve coupled with structural factors and, instead, is adopting models of fracture toughness that represent both the temperature trends and the scatter in the data with high accuracy.