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Author: Claire Leguen Publisher: ISBN: Category : Languages : en Pages : 187
Book Description
During this study, the correlation between the evolution of the prior austenitic grain size and of the precipitation state during thermal treatment performed on steels is presented. To do this, the precipitation state has been finely characterized. Precipitate volume fractions were measured by plasma spectroscopy. Transmission Electron Microscopy (TEM) was used to determine the precipitate size distributions (HAADF images) and the precipitate chemical composition (EDX, EELS for carbon and nitrogen). In order to treat ELLS spectra obtained on complex carbonitrides (V,Nb,Ti)(C,N), a routine based on the Least Mean square Fitting have been developed. Results obtained with this method are in good agreement with those obtained by EDX analysis for metallic elements (Nb, V, Ti, ...). Then, grain size distributions were determined using a special etching called "Bechet-Beaujard", which reveals the prior austenite grain boundaries. Two alloys have been characterized in this study. (i) A model alloy, the FeVNbCN, which presents two precipitate types, NbC and VCN. This alloy was chosen to study the role of nitrogen on the precipitation state during reversion treatments. A model predicting the precipitation kinetics, coupled with a model for grain growth, give a good agreement with experimental results on grain sizes, precipitate sizes and on precipitate volume fraction. (ii) An industrial steel, the 16MnCr5+Nb was also studied. This alloy exhibits the presence of AlN and NbC precipitates. The correlation obtained between the Prior Austenite Grain Size and the evolution of the precipitation state shows that a large volume fraction of small precipitates allows a great pinning of grain boundaries. Finally, during thermo-mechanical treatments performed in the industry, some large grains may grow faster than smaller grains, leading to the so-called abnormal grain growth. This kind of growth can lead to undesirable mechanical instabilities. We have developed a criterium for abnormal grain growth which predicts the risk of such growth for a given precipitation state. This model presents a good agreement with all experimental results for both studied alloys.
Author: Claire Leguen Publisher: ISBN: Category : Languages : en Pages : 187
Book Description
During this study, the correlation between the evolution of the prior austenitic grain size and of the precipitation state during thermal treatment performed on steels is presented. To do this, the precipitation state has been finely characterized. Precipitate volume fractions were measured by plasma spectroscopy. Transmission Electron Microscopy (TEM) was used to determine the precipitate size distributions (HAADF images) and the precipitate chemical composition (EDX, EELS for carbon and nitrogen). In order to treat ELLS spectra obtained on complex carbonitrides (V,Nb,Ti)(C,N), a routine based on the Least Mean square Fitting have been developed. Results obtained with this method are in good agreement with those obtained by EDX analysis for metallic elements (Nb, V, Ti, ...). Then, grain size distributions were determined using a special etching called "Bechet-Beaujard", which reveals the prior austenite grain boundaries. Two alloys have been characterized in this study. (i) A model alloy, the FeVNbCN, which presents two precipitate types, NbC and VCN. This alloy was chosen to study the role of nitrogen on the precipitation state during reversion treatments. A model predicting the precipitation kinetics, coupled with a model for grain growth, give a good agreement with experimental results on grain sizes, precipitate sizes and on precipitate volume fraction. (ii) An industrial steel, the 16MnCr5+Nb was also studied. This alloy exhibits the presence of AlN and NbC precipitates. The correlation obtained between the Prior Austenite Grain Size and the evolution of the precipitation state shows that a large volume fraction of small precipitates allows a great pinning of grain boundaries. Finally, during thermo-mechanical treatments performed in the industry, some large grains may grow faster than smaller grains, leading to the so-called abnormal grain growth. This kind of growth can lead to undesirable mechanical instabilities. We have developed a criterium for abnormal grain growth which predicts the risk of such growth for a given precipitation state. This model presents a good agreement with all experimental results for both studied alloys.
Author: T. Gladman Publisher: CRC Press ISBN: 1000107086 Category : Technology & Engineering Languages : en Pages : 184
Book Description
Grain Size Control provides an excellent account of the understanding of many matters concerning grains, grain structure, and grain growth in controlling the grain size of polycrystalline metals. It considers the application of the principles of grain growth.
Author: The Chinese Society for Metals Publisher: Springer ISBN: 3319487671 Category : Technology & Engineering Languages : en Pages : 1147
Book Description
This is a collection of papers presented at the joint conference of the 7th International Conference on High Strength Low Alloy Steels (HSLA Steels 2015), the International Conference on Microalloying 2015 (Microalloying 2015), and the International Conference on Offshore Engineering Steels 2015 (OES 2015). The papers focus on the exchange of the latest scientific and technological progresses on HSLA steels, microalloying steels, and offshore engineering steels over the past decades. The contributions are intended to strengthen cooperation between universities and research institutes, and iron and steel companies and users, and promote the further development in the fields all over the world.
Author: Elena Pereloma Publisher: Elsevier ISBN: 0857096117 Category : Technology & Engineering Languages : en Pages : 673
Book Description
The processing-microstructure-property relationships in steels continue to present challenges to researchers because of the complexity of phase transformation reactions and the wide spectrum of microstructures and properties achievable. This major two-volume work summarises the current state of research on phase transformations in steels and its implications for the emergence of new steels with enhanced engineering properties.Volume 2 reviews current research on diffusionless transformations and phase transformations in high strength steels, as well as advances in modelling and analytical techniques which underpin this research. Chapters in part one discuss the crystallography and kinetics of martensite transformations, the morphology, substructure and tempering of martensite as well as shape memory in ferrous alloys. Part two summarises research on phase transformations in high strength low alloy (HSLA) steels, transformation induced plasticity (TRIP)-assisted multiphase steels, quenched and partitioned steels, advanced nanostructured bainitic steels, high manganese twinning induced plasticity (TWIP) and maraging steels. The final two parts of the book review advances in modelling and the use of advanced analytical techniques to improve our understanding of phase transformations in steels.With its distinguished editors and distinguished international team of contributors, the two volumes of Phase transformations in steels is a standard reference for all those researching the properties of steel and developing new steels in such areas as automotive engineering, oil and gas and energy production. - Alongside its companion volume, this major two-volume work summarises the current state of research on phase transformations in steels - Reviews research on diffusionless transformations and phase transformations in high strength steels - Examines advances in modelling and the use of advanced analytical techniques to improve understanding of phase transformations in steels
Author: Elena Pereloma Publisher: Elsevier ISBN: 0857096109 Category : Technology & Engineering Languages : en Pages : 657
Book Description
The processing-microstructure-property relationships in steels continue to present challenges to researchers because of the complexity of phase transformation reactions and the wide spectrum of microstructures and properties achievable. This major two-volume work summarises the current state of research on phase transformations in steels and its implications for the emergence of new steels with enhanced engineering properties.Volume 1 reviews fundamentals and diffusion-controlled phase transformations. After a historical overview, chapters in part one discuss fundamental principles of thermodynamics, diffusion and kinetics as well as phase boundary interfaces. Chapters in part two go on to consider ferrite formation, proeutectoid ferrite and cementite transformations, pearlite formation and massive austenite-ferrite phase transformations. Part three discusses the mechanisms of bainite transformations, including carbide-containing and carbide-free bainite. The final part of the book considers additional driving forces for transformation including nucleation and growth during austenite-to-ferrite phase transformations, dynamic strain-induced ferrite transformations (DIST) as well as the effects of magnetic fields and heating rates.With its distinguished editors and distinguished international team of contributors, the two volumes of Phase transformations in steels is a standard reference for all those researching the properties of steel and developing new steels in such areas as automotive engineering, oil and gas and energy production. - Discusses the fundamental principles of thermodynamics, diffusion and kinetics - Considers various transformations, including ferrite formation, proeutectoid ferrite and cementite transformations - Considers additional driving forces for transformation including nucleation and growth during austenite-to-ferrite phase transformations
Author: T. Gladman Publisher: CRC Press ISBN: 1000150291 Category : Technology & Engineering Languages : en Pages : 202
Book Description
Grain Size Control provides an excellent account of the understanding of many matters concerning grains, grain structure, and grain growth in controlling the grain size of polycrystalline metals. It considers the application of the principles of grain growth.
Author: H.K.D.H. Bhadeshia Publisher: CRC Press ISBN: 1351574809 Category : Technology & Engineering Languages : en Pages : 914
Book Description
This is the third edition of the book, much expanded to include and incorporate important developments in the subject over the last fifteen years. The book represents a comprehensive treatise on all aspects of the bainite transformation, from the choreography of atoms during the phase change to length scales that are typical of engineering applications. The alloy design that emerges from this explains the role of solute additions, and the pernicious effects of impurities such as hydrogen. The picture presented is self-consistent and therefore is able to guide the reader on the exploitation of theory to the design of some of the most exciting steels, including the world’s first bulk nanostructured metal.
Author: Carlos Garcia-Mateo Publisher: MDPI ISBN: 3039288571 Category : Technology & Engineering Languages : en Pages : 166
Book Description
The microstructures of both martensite and bainite, although sharing some common features, depict a plethora of subtle differences that made them unique when studied in further detail. Tailoring the final properties of a microstructure based on one or the other as well as in combination with others and exploring more sophisticated concepts, such as Q&P and nanostructured bainite, are the topics which are the focus of research around the world. In understanding the key microstructural parameters controlling the final properties as well as definition of adequate process parameters to attain the desired microstructures requires that a proper understanding of the mechanism ruling their transformation and a detailed characterization first be acheived. The development of new and powerful scientific techniques and equipment (EBSD, APT, HRTEM, etc.) allow us to gain fundamental insights that help to establish some of the principles by which those microstructures are known. The developments accompanying such findings lead to further developments and intensive research providing the required metallurgical support.
Author: Claire Leguen
Author: Claire Leguen
Author: T. Gladman
Author: The Chinese Society for Metals
Author: Elena Pereloma
Author: Elena Pereloma
Author: Michael Wesley Wisti
Author: T. Gladman
Author: D. H. Stone
Author: H.K.D.H. Bhadeshia
Author: Carlos Garcia-Mateo