The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Peter Hodgson - One of the best experts on this subject based on the ideXlab platform.
-
Ultrafine grained structure formation in steels using dynamic strain Induced Transformation processing
International Materials Reviews, 2007Co-Authors: Hossein Beladi, Georgina Kelly, Peter HodgsonAbstract:The refinement of ferrite grain size is the most generally accepted approach to simultaneously improve the strength and toughness in steels. Historically, the level of ferrite refinement is limited...
-
the evolution of ultrafine ferrite formation through dynamic strain Induced Transformation
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: Hossein Beladi, Georgina Kelly, Alireza Shokouhi, Peter HodgsonAbstract:Abstract Hot torsion testing of a C–Mn–V steel was used to study the evolution of ultrafine ferrite (UFF) formation by dynamic strain-Induced Transformation (DSIT) in conjunction with air-cooling for two prior austenite grain sizes. This study evaluated not only the evolution of DSIT ferrite during straining, but also the grain growth behaviour of DSIT ferrite grains during post-deformation cooling. For both austenite grain sizes, the DSIT ferrite initially nucleated on/or near prior austenite grain boundaries at an early stage of Transformation followed by the grain interiors. The prior austenite grain size affected the distribution of DSIT ferrite nucleation sites at an early stage of Transformation and the subsequent coarsening behaviour of the grain boundary (GB) and the intragranular ferrite (IG) grains during post-deformation cooling. For the fine prior austenite grain size, the distribution of DSIT ferrite grains was more homogenous compared with the coarse austenite and the coarsening occurred not only in the GB ferrite grains but also in the IG ferrite grains. However, the ferrite coarsening mostly occurred for the IG ferrite rather than the GB ferrite grains in the coarse austenite. The result suggests that normal grain growth occurred during the overall Transformation in the GB ferrite grains for the coarse initial austenite grain size.
-
the production of ultrafine ferrite in low carbon steel by strain Induced Transformation
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2002Co-Authors: M R Hickson, Georgina Kelly, P J Hurley, R K Gibbs, Peter HodgsonAbstract:An investigation into the production of ultrafine (1 µm) equiaxed ferrite (UFF) grains in low-carbon steel was made using laboratory rolling, compression dilatometry, and hot torsion techniques. It was found that the hot rolling of thin strip, with a combination of high shear strain and high undercooling, provided the conditions most suitable for the formation of this type of microstructure. Although high strains could be applied in compression and torsion experiments, large volume fractions of UFF were not observed in those samples, possibly due to the lower level of undercooling achieved. It is thought that ferrite refinement was due to a strain-Induced Transformation process, and that ferrite grains nucleated on parallel and linear deformation bands that traversed austenite grains. These bands formed during the deformation process, and the undercooling provided by the contact between the strip and the work rolls was sufficient to drive the Transformation to homogeneous UFF grains.
-
analysis and characterisation of ultra fine ferrite produced during a new steel strip rolling process
Scripta Materialia, 1999Co-Authors: P J Hurley, Peter Hodgson, Barry C MuddleAbstract:The designing of processing routes that minimize the final ferrite grain size is essential for the development of high strength steels with improved toughness and ductility. In this paper, a novel procedure for producing ultra-fine ferrite is investigated. This method is attractive in terms of its relative simplicity and ability to refine the ferrite grain size in relatively low cost steels. In an earlier paper, it was stated that the high level of ferrite grain refinement occurring during this process was likely to be the result of a strain-Induced Transformation mechanism. Thus, it has been termed the SITR (strain-Induced Transformation rolling) process. In the present paper, detailed characterization of the fine ferrite produced using this technique has been performed with the aim of providing a deeper insight into the important factors giving rise to its generation.
Emin Semih Perdahcioglu - One of the best experts on this subject based on the ideXlab platform.
-
strain direction dependency of martensitic Transformation in austenitic stainless steels the effect of gamma texture
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: P Hilkhuijsen, Emin Semih Perdahcioglu, H J M Geijselaers, T C Bor, Van Den A H Boogaard, Remko AkkermanAbstract:Uniaxial tensile tests on both a non-textured and a highly textured, fully austenitic stainless steel were performed in both the rolling and the transverse directions. Both materials show mechanically Induced phase Transformation from the austenitic FCC to the martensitic BCC phase. Differences in overall Transformation behavior are observed between the two steels. No direction-dependent Transformation behavior is present during deformation of the nontextured steel. However, when a strong texture is present, differences in Transformation behavior during deformation in different directions can be observed clearly. The ‘stress Induced Transformation’ theory, in combination with the austenite texture measured before deformation, is used to explain and model the Transformation behavior when straining in different directions. The theoretical results of the stress-Induced Transformation theory compare well with the measured austenitic textures after deformation and the recorded stress vs martensite fraction curves.
-
influence of stress state and strain path on deformation Induced martensitic Transformations
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Emin Semih Perdahcioglu, H J M Geijselaers, J. HuetinkAbstract:The mechanically Induced Transformation behavior of 12Crsingle bond9Nisingle bond 4Mo (ASTM A 564) austenitic stainless steel is investigated in different stress states. This phenomenon is studied experimentally on a plane-stress biaxial test facility. The facility can load a sheet specimen simultaneously in shear and tension which enables us to investigate the effect of stress state on Transformation kinetics. The martensite fraction is monitored via a magnetic sensor while the strain is measured using a camera and a dot-tracking software.
H J M Geijselaers - One of the best experts on this subject based on the ideXlab platform.
-
strain direction dependency of martensitic Transformation in austenitic stainless steels the effect of gamma texture
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: P Hilkhuijsen, Emin Semih Perdahcioglu, H J M Geijselaers, T C Bor, Van Den A H Boogaard, Remko AkkermanAbstract:Uniaxial tensile tests on both a non-textured and a highly textured, fully austenitic stainless steel were performed in both the rolling and the transverse directions. Both materials show mechanically Induced phase Transformation from the austenitic FCC to the martensitic BCC phase. Differences in overall Transformation behavior are observed between the two steels. No direction-dependent Transformation behavior is present during deformation of the nontextured steel. However, when a strong texture is present, differences in Transformation behavior during deformation in different directions can be observed clearly. The ‘stress Induced Transformation’ theory, in combination with the austenite texture measured before deformation, is used to explain and model the Transformation behavior when straining in different directions. The theoretical results of the stress-Induced Transformation theory compare well with the measured austenitic textures after deformation and the recorded stress vs martensite fraction curves.
-
influence of stress state and strain path on deformation Induced martensitic Transformations
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Emin Semih Perdahcioglu, H J M Geijselaers, J. HuetinkAbstract:The mechanically Induced Transformation behavior of 12Crsingle bond9Nisingle bond 4Mo (ASTM A 564) austenitic stainless steel is investigated in different stress states. This phenomenon is studied experimentally on a plane-stress biaxial test facility. The facility can load a sheet specimen simultaneously in shear and tension which enables us to investigate the effect of stress state on Transformation kinetics. The martensite fraction is monitored via a magnetic sensor while the strain is measured using a camera and a dot-tracking software.
Remko Akkerman - One of the best experts on this subject based on the ideXlab platform.
-
strain direction dependency of martensitic Transformation in austenitic stainless steels the effect of gamma texture
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: P Hilkhuijsen, Emin Semih Perdahcioglu, H J M Geijselaers, T C Bor, Van Den A H Boogaard, Remko AkkermanAbstract:Uniaxial tensile tests on both a non-textured and a highly textured, fully austenitic stainless steel were performed in both the rolling and the transverse directions. Both materials show mechanically Induced phase Transformation from the austenitic FCC to the martensitic BCC phase. Differences in overall Transformation behavior are observed between the two steels. No direction-dependent Transformation behavior is present during deformation of the nontextured steel. However, when a strong texture is present, differences in Transformation behavior during deformation in different directions can be observed clearly. The ‘stress Induced Transformation’ theory, in combination with the austenite texture measured before deformation, is used to explain and model the Transformation behavior when straining in different directions. The theoretical results of the stress-Induced Transformation theory compare well with the measured austenitic textures after deformation and the recorded stress vs martensite fraction curves.
Nancy H Colburn - One of the best experts on this subject based on the ideXlab platform.
-
dominant negative c jun tam67 target genes hmga1 is required for tumor promoter Induced Transformation
Oncogene, 2004Co-Authors: Arindam Dhar, Raymond Reeves, Linda Resar, Nancy H ColburnAbstract:Activation of the transcription factor AP-1 (activator protein-1) is required for tumor promotion and maintenance of malignant phenotype. A number of AP-1-regulated genes that play a role in tumor progression have been identified. However, AP-1-regulated genes driving tumor induction are yet to be defined. Previous studies have established that expression of a dominant-negative c-Jun (TAM67) inhibits phorbol 12-tetradecanoyl-13-acetate (TPA)-Induced AP-1 transactivation as well as Transformation in mouse epidermal JB6/P+ cells and tumor promotion in mouse skin carcinogenesis. In this study, we utilized the tumor promotion-sensitive JB6/P+ cells to identify AP-1-regulated TAM67 target genes and to establish causal significance in Transformation for one target gene. A 2700 cDNA microarray was queried with RNA from TPA-treated P+ cells with or without TAM67 expression. Under conditions in which TAM expression inhibited TPA-Induced Transformation, microarray analysis identified a subset of six genes Induced by TPA and suppressed by TAM67. One of the identified genes, the high-mobility group protein A1 (Hmga1) is Induced by TPA in P+, but not in Transformation-resistant P cells. We show that TPA induction of the architectural transcription factor HMGA1 is inhibited by TAM67, is extracellular–signal-regulated kinase (ERK)-activation dependent, and is mediated by AP-1. HMGA1 antisense construct transfected into P+ cells blocked HMGA1 protein expression and inhibited TPA-Induced Transformation indicating that HMGA1 is required for Transformation. HMGA1 is not however sufficient as HMGA1a or HMGA1b overexpression did not confer Transformation sensitivity on P− cells. Although HMGA1 expression is ERK dependent, it is not the only ERK-dependent event required for Transformation because it does not suffice to rescue ERK-deficient P− cells. Our study shows (a) TAM 67 when it inhibits AP-1 and Transformation, targets a relatively small number of genes; (b) HMGA1, a TAM67 target gene, is causally related to Transformation and therefore a potentially important target for cancer prevention.
