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Annika Borgenstam - One of the best experts on this subject based on the ideXlab platform.
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A Transmission Electron Microscopy Study of Plate Martensite Formation in High-carbon Low Alloy Steels
Journal of Materials Science & Technology, 2013Co-Authors: Albin Stormvinter, Peter Hedstrom, Annika BorgenstamAbstract:The martensitic microstructures in two high-carbon low alloy steels have been investigated by classical and automated crystallographic analysis under a transmission electron microscope. It is found ...
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Thermodynamically Based Prediction of the Martensite Start Temperature for Commercial Steels
Metallurgical and Materials Transactions A, 2012Co-Authors: Albin Stormvinter, Annika Borgenstam, John ÅgrenAbstract:A thermodynamic method for predicting the Martensite start temperature of commercial steels is developed. It is based mainly on information on M s from binary Fe-X systems obtained from experiments with very rapid cooling, and M s values for lath and Plate Martensite are treated separately. Comparison with the experimental M s of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of M s from commercial steels.
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Effect of Carbon Content on the Orientation Relationship between Austenite and bct-Martensite in Fe-C Alloys resolved by Electron Backscattered Diffraction
2012Co-Authors: Albin Stormvinter, Goro Miyamoto, Tadashi Furuhara, Annika BorgenstamAbstract:Martensitic steels have become very important engineering materials in modern society. Crucial parts of everyday products are made of martensitic steels, from surgical needles and razor blades to car components and large-scale excavators. Martensite, which results from a rapid diffusionless phase transformation, has a complex nature that is challenging to characterize and to classify. Moreover the possibilities for modeling of this phase transformation have been limited, since its thermodynamics and kinetics are only reasonably well understood. However, the recent development of characterization capabilities and computational techniques, such as CALPHAD, and its applicability to ferrous Martensite has not been fully explored yet.In the present work, a thermodynamic method for predicting the Martensite start temperature (Ms) of commercial steels is developed. It is based mainly on information on Ms from binary Fe-X systems obtained from experiments using very rapid cooling, and Ms values for lath and Plate Martensite are treated separately. Comparison with the experimental Ms of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of Ms from commercial steels.A major part of the present work is dedicated to the effect of carbon content on the morphological transition from lath- to Plate Martensite in steels. A range of metallographic techniques were employed: (1) Optical microscopy to study the apparent morphology; (2) Transmission electron microscopy to study high-carbon Plate Martensite; (3) Electron backscattered diffraction to study the variant pairing tendency of Martensite. The results indicate that a good understanding of the martensitic microstructure can be achieved by combining qualitative metallography with quantitative analysis, such as variant pairing analysis. This type of characterization methodology could easily be extended to any alloying system and may thus facilitate Martensite characterization in general.Finally, a minor part addresses inverse bainite, which may form in high-carbon alloys. Its coupling to regular bainite is discussed on the basis of symmetry in the Fe-C phase diagram.
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investigation of lath and Plate Martensite in a carbon steel
Solid State Phenomena, 2011Co-Authors: Albin Stormvinter, Peter Hedstrom, Annika BorgenstamAbstract:Martensite in carbon steels forms in different morphologies, often referred to as lath andPlate Martensite. The alloy composition has a strong effect on the morphology, for instance in car-bon stee ...
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Some remarks on the nucleation and growth of Martensite
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999Co-Authors: Annika BorgenstamAbstract:Abstract It is generally agreed that the difficult step in the formation of isothermal as well as athermal Martensite is the nucleation since the growth occurs at a high speed. Previously the difference between M s and M g , the temperature below which Martensite can grow if it is already nucleated, was determined for an Fe-1.62%C alloy. The difference was surprisingly small indicating that the difference in driving force for nucleation and growth is small. This experimental result is here compared with results on both athermal and isothermal Martensite. A discussion about the critical step for the formation of lath and Plate Martensite formed by rapid continuous cooling is also given.
Tadashi Furuhara - One of the best experts on this subject based on the ideXlab platform.
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Effect of Carbon Content on the Orientation Relationship between Austenite and bct-Martensite in Fe-C Alloys resolved by Electron Backscattered Diffraction
2012Co-Authors: Albin Stormvinter, Goro Miyamoto, Tadashi Furuhara, Annika BorgenstamAbstract:Martensitic steels have become very important engineering materials in modern society. Crucial parts of everyday products are made of martensitic steels, from surgical needles and razor blades to car components and large-scale excavators. Martensite, which results from a rapid diffusionless phase transformation, has a complex nature that is challenging to characterize and to classify. Moreover the possibilities for modeling of this phase transformation have been limited, since its thermodynamics and kinetics are only reasonably well understood. However, the recent development of characterization capabilities and computational techniques, such as CALPHAD, and its applicability to ferrous Martensite has not been fully explored yet.In the present work, a thermodynamic method for predicting the Martensite start temperature (Ms) of commercial steels is developed. It is based mainly on information on Ms from binary Fe-X systems obtained from experiments using very rapid cooling, and Ms values for lath and Plate Martensite are treated separately. Comparison with the experimental Ms of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of Ms from commercial steels.A major part of the present work is dedicated to the effect of carbon content on the morphological transition from lath- to Plate Martensite in steels. A range of metallographic techniques were employed: (1) Optical microscopy to study the apparent morphology; (2) Transmission electron microscopy to study high-carbon Plate Martensite; (3) Electron backscattered diffraction to study the variant pairing tendency of Martensite. The results indicate that a good understanding of the martensitic microstructure can be achieved by combining qualitative metallography with quantitative analysis, such as variant pairing analysis. This type of characterization methodology could easily be extended to any alloying system and may thus facilitate Martensite characterization in general.Finally, a minor part addresses inverse bainite, which may form in high-carbon alloys. Its coupling to regular bainite is discussed on the basis of symmetry in the Fe-C phase diagram.
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Characterization of Substructure Evolution in Ferrous Lenticular Martensite
Materials Science Forum, 2010Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Tadashi MakiAbstract:This study investigated the substructure evolution in lenticular Martensite. The substructure of lenticular Martensite changes from fine transformation twins in the midrib and twinned region to a high density of dislocations in the untwinned region during growth. On the basis of careful observation of the morphology and substructure of midrib and examination of the stress-induced growth behavior of thin Plate Martensite, we concluded that the midrib in lenticular Martensite is thin Plate Martensite itself. Tangled and curved dislocations appeared near the Martensite-austenite boundary of the untwinned region in Fe-33Ni and in the entire untwinned region in Fe-31Ni, because the Martensite inherited the accommodation dislocations in the surrounding austenite. The difference of Ms temperature causes the difference in the substructure between Fe-33Ni and Fe-31Ni. The higher Ms temperature of Fe-31Ni induces the plastic deformation of the surrounding austenite at an earlier stage of transformation, resulting in the appearance of tangled and curved dislocations in the entire untwinned region.
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precise measurement of strain accommodation in austenite matrix surrounding Martensite in ferrous alloys by electron backscatter diffraction analysis
Acta Materialia, 2009Co-Authors: Goro Miyamoto, Akinobu Shibata, T. Maki, Tadashi FuruharaAbstract:Local strain distributions in austenite matrix that is deformed to accommodate shape strain associated with formation of Martensite were investigated by means of electron backscatter diffraction (EBSD) analysis for various morphologies of lath, lenticular and thin Plate Martensite in ferrous alloys. By detecting small changes in EBSD patterns through image analysis of the patterns, components of both strain and rotation tensors in austenite matrix adjacent to Martensite were measured quantitatively. In the austenite matrix surrounding thin Plate Martensite, the magnitude of components of strain tensor is nearly as large as those of rotation tensor, implying that shape strain of thin Plate Martensite is accommodated by elastic deformation of austenite. On the other hand, in the austenite matrices surrounding lenticular and lath Martensite, components of strain tensor are found to be much smaller than those of rotation tensor even near the austenite/Martensite interface. This indicates that most of the shape strain associated with the formation of lenticular and lath Martensite is accommodated by plastic deformation in the austenite matrix. The misorientation axis of austenite adjacent to lenticular and lath Martensite coincides well with that predicted from the phenomenological theory of Martensite crystallography.
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Substructures of lenticular Martensites with different Martensite start temperatures in ferrous alloys
Acta Materialia, 2009Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Tadashi MakiAbstract:Abstract This study investigated the substructures of lenticular Martensites with different Martensite start temperatures (Ms) by transmission electron microscopy. Observation of Fe–33Ni revealed a substructural change from fine transformation twins in the midrib and twinned region to several sets of screw dislocations in the untwinned region during growth. Tangled and curved dislocations also appeared near the Martensite–austenite interface of the untwinned region, as the Martensite inherited the dislocations in the surrounding austenite. In contrast, curved and tangled dislocations appeared in the entire untwinned region in Fe–31Ni and in the whole Martensite Plate in Fe–20.5Ni–35Co, as the higher Ms temperatures facilitated the plastic deformation of the surrounding austenite. Thermally transformed thin Plate Martensite in Fe–31Ni–10Co–3Ti grew into a lenticular shape accompanied by a substructure with dislocations after deformation at temperatures above the Ms temperature. The change in the substructure of lenticular Martensite presumably resulted from the local temperature rise in the Martensite Plate.
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The Origin of Midrib in Lenticular Martensite
MATERIALS TRANSACTIONS, 2008Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Toshio Murakami, Tadashi MakiAbstract:In the present paper, the origin of midrib in lenticular Martensite is clarified by examining the similarity between midrib and thin Plate Martensite in detail and studying the stress-induced growth behavior of thin Plate Martensite at various temperatures. Although lenticular Martensite, especially midrib, exhibits a zigzag array in general, some Martensite Plates which are branched or kinked were also observed as thin Plate Martensite. The substructure of midrib is completely twinned and the orientation relationship of midrib with respect to austenite is close to Greninger–Troiano relationship. These morphology, substructure and crystallographic features of midrib in lenticular Martensite are quite similar to those of thin Plate Martensite. Furthermore, stress-induced growth behavior of thin Plate Martensite changes with deformation temperature. Thermally-transformed thin Plate Martensite grows keeping a thin Plate shape when deformed at temperature close to the Ms temperature. However, it grows into a lenticular shape accompanying a substructure with a high density of dislocations after deformation at temperature much higher than Ms temperature. Therefore, it is concluded that midrib in lenticular Martensite is thin Plate Martensite itself. The difference between lenticular Martensite and thin Plate Martensite is only in their growth behaviors. [doi:10.2320/matertrans.MRA2007296]
Jer-ren Yang - One of the best experts on this subject based on the ideXlab platform.
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crystallographic examination of the interaction between texture evolution mechanically induced martensitic transformation and twinning in nanostructured bainite
Journal of Alloys and Compounds, 2018Co-Authors: Lucia Moralesrivas, Jer-ren Yang, Fady Mamdouh Fawzy Archie, Stefan Zaefferer, Miguel Benitoalfonso, Shao Pu Tsai, Dierk Raabe, C Garciamateo, F G CaballeroAbstract:Abstract The deformation mechanisms operating in nanostructured bainite, leading to its excellent combination of strength and ductility, are far from being understood. Its nanocrystalline nature and its multiphase-evolving structure underlie the plastic flow and the strain-hardening behaviour. In this work, the microstructural and crystallographic bulk changes of a high-C nanostructured bainite under tensile testing have been evaluated. The influence of the mechanically-induced transformation of the C-enriched retained austenite into α Martensite and other deformation mechanisms on the texture evolution has been analysed by electron backscatter diffraction (EBSD). Additionally, the undeformed and the deformed conditions have been examined by electron channelling contrast imaging (ECCI) and transmission electron microscopy (TEM). Results reveal the presence of Plate Martensite and suggest a strong variant selection during the transformation, mainly responsible for the texture observed. Mechanical twinning in austenite seems to be basically the mechanism of accommodation of the displacive bainitic transformation, while some direct interaction with the applied stress also appears.
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Martensite Midrib in an Fe-1C-17Cr Stainless Steel
Solid State Phenomena, 2011Co-Authors: Jer-ren Yang, Hsin Yi Lee, Hung-wei Yen, Hsiao-tzu ChangAbstract:An Fe-1.0C-17Cr (wt.%) stainless steel was subjected to subzero treatment to investigated the structure of Martensite midrib. The midrib region appeared in the thin Plate and lenticular Martensites have been observed detailed by TEM. The TEM result reveals that the transformations of thin Plate Martensite and lenticular Martensite are initiated at the same midrib region. The former keeps the lattice-invariant deformation mode of twinning during subsequent growth, whereas the latter combines both twinning and slip modes. Midrib region is a preferential position for carbide precipitations after tempering. M3C and M23C6 carbide were found in this alloy, and related to the ferrite by Bagaryatsky OR and K-S OR, respectively.
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Substructures of Martensite in Fe–1C–17Cr stainless steel
Scripta Materialia, 2010Co-Authors: Hsin Yi Lee, Hung-wei Yen, Hsiao-tzu Chang, Jer-ren YangAbstract:An Fe–1.0C–17Cr (wt.%) stainless steel was subjected to subzero treatment to investigate the structure of the Martensite midrib. During the course of the isothermal holding in liquid nitrogen (−196 °C), the thin-Plate Martensite formed first, and lenticular Martensite later. The substructures of thin-Plate Martensites and lenticular Martensite were examined using transmission electron microscopy, focusing on the details of the midrib. The results provide strong evidence to suggest that thin-Plate Martensite can be transformed into lenticular Martensite.
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Martensitic transformations in AISI 440C stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Jer-ren Yang, C.h. WangAbstract:Abstract AISI 440C stainless steel possesses a low M s temperature, which is far below room temperature. After subzero treatment in liquid nitrogen, the steel forms Plate Martensite with significant amounts of retained austenite. Dilatometric experiments with microstructural observation were performed to investigate the tempered Martensite and the decomposed retained austenite during multiple tempering treatments. The results indicate that a complete transformation of retained austenite can be more easily achieved by multiple tempering cycles than by a single long-time cycle. The possible mechanism for the decomposition of retained austenite during multiple tempering cycles is attributed to the invariant-plane-strain of the prior martensitic transformation extending accommodation defects to the adjacent retained austenite, which favors further transformations in the subsequent tempering operations.
Tadashi Maki - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Substructure Evolution in Ferrous Lenticular Martensite
Materials Science Forum, 2010Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Tadashi MakiAbstract:This study investigated the substructure evolution in lenticular Martensite. The substructure of lenticular Martensite changes from fine transformation twins in the midrib and twinned region to a high density of dislocations in the untwinned region during growth. On the basis of careful observation of the morphology and substructure of midrib and examination of the stress-induced growth behavior of thin Plate Martensite, we concluded that the midrib in lenticular Martensite is thin Plate Martensite itself. Tangled and curved dislocations appeared near the Martensite-austenite boundary of the untwinned region in Fe-33Ni and in the entire untwinned region in Fe-31Ni, because the Martensite inherited the accommodation dislocations in the surrounding austenite. The difference of Ms temperature causes the difference in the substructure between Fe-33Ni and Fe-31Ni. The higher Ms temperature of Fe-31Ni induces the plastic deformation of the surrounding austenite at an earlier stage of transformation, resulting in the appearance of tangled and curved dislocations in the entire untwinned region.
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Substructures of lenticular Martensites with different Martensite start temperatures in ferrous alloys
Acta Materialia, 2009Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Tadashi MakiAbstract:Abstract This study investigated the substructures of lenticular Martensites with different Martensite start temperatures (Ms) by transmission electron microscopy. Observation of Fe–33Ni revealed a substructural change from fine transformation twins in the midrib and twinned region to several sets of screw dislocations in the untwinned region during growth. Tangled and curved dislocations also appeared near the Martensite–austenite interface of the untwinned region, as the Martensite inherited the dislocations in the surrounding austenite. In contrast, curved and tangled dislocations appeared in the entire untwinned region in Fe–31Ni and in the whole Martensite Plate in Fe–20.5Ni–35Co, as the higher Ms temperatures facilitated the plastic deformation of the surrounding austenite. Thermally transformed thin Plate Martensite in Fe–31Ni–10Co–3Ti grew into a lenticular shape accompanied by a substructure with dislocations after deformation at temperatures above the Ms temperature. The change in the substructure of lenticular Martensite presumably resulted from the local temperature rise in the Martensite Plate.
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The Origin of Midrib in Lenticular Martensite
MATERIALS TRANSACTIONS, 2008Co-Authors: Akinobu Shibata, Tadashi Furuhara, Shigekazu Morito, Toshio Murakami, Tadashi MakiAbstract:In the present paper, the origin of midrib in lenticular Martensite is clarified by examining the similarity between midrib and thin Plate Martensite in detail and studying the stress-induced growth behavior of thin Plate Martensite at various temperatures. Although lenticular Martensite, especially midrib, exhibits a zigzag array in general, some Martensite Plates which are branched or kinked were also observed as thin Plate Martensite. The substructure of midrib is completely twinned and the orientation relationship of midrib with respect to austenite is close to Greninger–Troiano relationship. These morphology, substructure and crystallographic features of midrib in lenticular Martensite are quite similar to those of thin Plate Martensite. Furthermore, stress-induced growth behavior of thin Plate Martensite changes with deformation temperature. Thermally-transformed thin Plate Martensite grows keeping a thin Plate shape when deformed at temperature close to the Ms temperature. However, it grows into a lenticular shape accompanying a substructure with a high density of dislocations after deformation at temperature much higher than Ms temperature. Therefore, it is concluded that midrib in lenticular Martensite is thin Plate Martensite itself. The difference between lenticular Martensite and thin Plate Martensite is only in their growth behaviors. [doi:10.2320/matertrans.MRA2007296]
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Martensitic Transformation in Thin Foils of an Fe-Ni-Co-Ti Shape Memory Alloy
Materials Science Forum, 2000Co-Authors: Shigekazu Morito, Tadashi Furuhara, Tomokazu Moritani, Tadashi MakiAbstract:The effect of specimen thickness on morphology and crystallography of α'(bct) Martensite was studied in an Fe-Ni-Co-Ti shape memory alloy. The specimens with- greater thickness than 0.5 mm form thin Plate Martensite which is characterized by a highly smooth and planar interface and has completely twinned internal structure. The Martensite formed in thin foil (about 0.1 μm thick) has irregular interfaces and the internal structure is completely or partially twinned. The width of transformation twins in Martensite formed in thin foil is smaller than that in bulk specimen. The Martensite/austenite orientation relationship in the bulk specimen is close to the Nishiyama relationship. In contrast, the orientation relationship of thin foil Martensite deviates by as much as 5° from the Nishiyama relationship.
Albin Stormvinter - One of the best experts on this subject based on the ideXlab platform.
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A Transmission Electron Microscopy Study of Plate Martensite Formation in High-carbon Low Alloy Steels
Journal of Materials Science & Technology, 2013Co-Authors: Albin Stormvinter, Peter Hedstrom, Annika BorgenstamAbstract:The martensitic microstructures in two high-carbon low alloy steels have been investigated by classical and automated crystallographic analysis under a transmission electron microscope. It is found ...
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Thermodynamically Based Prediction of the Martensite Start Temperature for Commercial Steels
Metallurgical and Materials Transactions A, 2012Co-Authors: Albin Stormvinter, Annika Borgenstam, John ÅgrenAbstract:A thermodynamic method for predicting the Martensite start temperature of commercial steels is developed. It is based mainly on information on M s from binary Fe-X systems obtained from experiments with very rapid cooling, and M s values for lath and Plate Martensite are treated separately. Comparison with the experimental M s of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of M s from commercial steels.
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Effect of Carbon Content on the Orientation Relationship between Austenite and bct-Martensite in Fe-C Alloys resolved by Electron Backscattered Diffraction
2012Co-Authors: Albin Stormvinter, Goro Miyamoto, Tadashi Furuhara, Annika BorgenstamAbstract:Martensitic steels have become very important engineering materials in modern society. Crucial parts of everyday products are made of martensitic steels, from surgical needles and razor blades to car components and large-scale excavators. Martensite, which results from a rapid diffusionless phase transformation, has a complex nature that is challenging to characterize and to classify. Moreover the possibilities for modeling of this phase transformation have been limited, since its thermodynamics and kinetics are only reasonably well understood. However, the recent development of characterization capabilities and computational techniques, such as CALPHAD, and its applicability to ferrous Martensite has not been fully explored yet.In the present work, a thermodynamic method for predicting the Martensite start temperature (Ms) of commercial steels is developed. It is based mainly on information on Ms from binary Fe-X systems obtained from experiments using very rapid cooling, and Ms values for lath and Plate Martensite are treated separately. Comparison with the experimental Ms of several sets of commercial steels indicates that the predictive ability is comparable to models based on experimental information of Ms from commercial steels.A major part of the present work is dedicated to the effect of carbon content on the morphological transition from lath- to Plate Martensite in steels. A range of metallographic techniques were employed: (1) Optical microscopy to study the apparent morphology; (2) Transmission electron microscopy to study high-carbon Plate Martensite; (3) Electron backscattered diffraction to study the variant pairing tendency of Martensite. The results indicate that a good understanding of the martensitic microstructure can be achieved by combining qualitative metallography with quantitative analysis, such as variant pairing analysis. This type of characterization methodology could easily be extended to any alloying system and may thus facilitate Martensite characterization in general.Finally, a minor part addresses inverse bainite, which may form in high-carbon alloys. Its coupling to regular bainite is discussed on the basis of symmetry in the Fe-C phase diagram.
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investigation of lath and Plate Martensite in a carbon steel
Solid State Phenomena, 2011Co-Authors: Albin Stormvinter, Peter Hedstrom, Annika BorgenstamAbstract:Martensite in carbon steels forms in different morphologies, often referred to as lath andPlate Martensite. The alloy composition has a strong effect on the morphology, for instance in car-bon stee ...