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Peter Hodgson - One of the best experts on this subject based on the ideXlab platform.

  • influence of coiling on microstructural evolution and mechanical properties of strip cast low carbon low niobium steel
    Materials Science Forum, 2016
    Co-Authors: Lu Jiang, Thomas Dorin, Ross K W Marceau, Nicole Stanford, Peter Hodgson
    Abstract:

    As-cast low-carbon low-niobium steels fabricated by direct strip casting (DSC) were treated by simulated coiling in the lab. Coiling temperatures were carefully selected: (1) 900 C (in the austenite); (2) 700 C (during the austenite-to-ferrite transformation); (3) 650 C (in the ferrite). Optical microscopy and transmission electron microscopy were used to examine the Microstructure constituents and the precipitates. Mechanical properties were evaluated by Vickers macrohardness measurements. The results show that coiling treatment has a strong influence on the Final Microstructure and mechanical properties, thus highlighting the necessity to carefully design the coiling treatment. In addition, the differences in hardness for the three coiling temperatures derive from a complex combination of different strengthening mechanisms.

  • Microstructure and hardness evolution during simulated coiling of a direct strip cast low carbon low niobium steel
    PTM 2015 : Proceedings of the Solid-Solid Phase Transformations in Inorganic Materials 2015 International Conference, 2015
    Co-Authors: Thomas Dorin, Peter Hodgson, Nicole Stanford
    Abstract:

    This paper examines the impact of coiling temperature and duration on the phase transformation and precipitation behavior of a low carbon and low niobium direct strip cast steel. Coiling was performed at three carefully chosen temperatures: (1) in the ferrite (600°C), (2) during the austenite decomposition (700°C) and (3) in the austenite (850°C). The coiling conditions were found to strongly affect the Final Microstructure and hardness response, thus highlighting the necessity to judiciously design the coiling treatment. Optical microscopy, and scanning and transmission electron microscopy were used to characterize the microstructural constituents (polygonal ferrite, bainite and pearlite) and the NbC precipitates. Vickers macrohardness measurements are utilized to quantify the mechanical properties. The differences in hardening kinetics for the three different temperatures are shown to come from a complex combination of strengthening contributions.

  • microstructural modeling of dynamic recrystallization using irregular cellular automata
    Computational Materials Science, 2008
    Co-Authors: Nima Yazdipour, C H J Davies, Peter Hodgson
    Abstract:

    Cellular automaton (CA) was used to simulate dynamic recrystallization (DRX) during thermomechanical deformation. Initial grain size, initial grain orientation and dislocation density were used as input data to the CA model. Flow curve, dislocation density, Final grain size and orientation, and DRX volume fraction were the output data which were compared with experimental data to validate the model. The model proposed in this work considered the thermomechanical parameters (e.g., temperature and strain rate) and their role on the nucleation and growth kinetics during DRX. It was shown that the CA model can predict the Final Microstructure and flow curve to a high degree of accuracy and was able to successfully simulate the volume fraction of DRX as a function of strain for a wide range of deformation conditions.

  • transformation behaviour in thermomechanically processed c mn si trip steels with and without nb
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999
    Co-Authors: Elena V Pereloma, Ilana Timokhina, Peter Hodgson
    Abstract:

    Abstract Two 0.2wt.% C–1.55wt.% Mn–1.5wt.% Si steels with and without the addition of 0.039 wt.% Nb were studied by laboratory simulations of controlled thermomechanical processing in a quench deformation dilatometer. The Microstructures were characterised using optical metallography, image analysis and scanning electron microscopy techniques. The effects of recrystallised and non-recrystallised austenite and discontinuous paths on the Final Microstructure were studied. The results have shown that the highest volume fraction of retained austenite is associated with a 400°C isothermal bainite transformation temperature and the presence of approximately 50% polygonal ferrite and acicular ferrite as a dominant second phase.

  • the effect of transformation path on the Final Microstructure of high and low silicon 0 1 wt c steels
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1998
    Co-Authors: Elena V Pereloma, Peter Hodgson
    Abstract:

    Two low-carbon steels with low (0.16 wt.%) and high (1.4 wt.%) Si contents were studied using laboratory simulations of thermomechanically controlled processing. Continuous cooling and discontinuous cooling schedules were utilised to evaluate the transformation behaviour of these steels. It has been found that both the transformation history and the state of austenite prior to transformation have a significant effect on the Final Microstructure. Both the prior austenite condition and the amount of ferrite prior to a change in cooling rate influence the morphology of second phase. The results have shown that to predict the Final Microstructure and mechanical properties it is not sufficient to model the process based only on average austenite composition and solute partitioning during austenite decomposition.

Amit Bandyopadhyay - One of the best experts on this subject based on the ideXlab platform.

  • surface modification of aisi 410 stainless steel using laser engineered net shaping lenstm
    Materials & Design, 2009
    Co-Authors: Vamsi B Krishna, Amit Bandyopadhyay
    Abstract:

    Abstract Surface modification of AISI 410 martensitic stainless steel was carried out by laser surface-melting using laser engineered net shaping (LENSTM). The Microstructures of laser surface-melted specimens showed varying amount of retained austenite depending on the processing parameters. The refinement and high strength of austenite as a result of increased scan speed and decreased laser power resulted in high amount of retained austenite in the Final Microstructure. Laser surface-melting of AISI 410 martensitic stainless steel at optimized processing parameters resulted in fine martensite with minimum retained austenite, leading to a 55% increase in the surface hardness compared to the hardness of conventionally heat treated samples. The inherent advantage of laser surface-melting using LENSTM is to control simultaneously both location and Microstructure leading to better service performance of components.

  • surface modification of aisi 410 stainless steel using laser engineered net shaping lenstm
    Materials & Design, 2009
    Co-Authors: Vamsi B Krishna, Amit Bandyopadhyay
    Abstract:

    Abstract Surface modification of AISI 410 martensitic stainless steel was carried out by laser surface-melting using laser engineered net shaping (LENSTM). The Microstructures of laser surface-melted specimens showed varying amount of retained austenite depending on the processing parameters. The refinement and high strength of austenite as a result of increased scan speed and decreased laser power resulted in high amount of retained austenite in the Final Microstructure. Laser surface-melting of AISI 410 martensitic stainless steel at optimized processing parameters resulted in fine martensite with minimum retained austenite, leading to a 55% increase in the surface hardness compared to the hardness of conventionally heat treated samples. The inherent advantage of laser surface-melting using LENSTM is to control simultaneously both location and Microstructure leading to better service performance of components.

Vamsi B Krishna - One of the best experts on this subject based on the ideXlab platform.

  • surface modification of aisi 410 stainless steel using laser engineered net shaping lenstm
    Materials & Design, 2009
    Co-Authors: Vamsi B Krishna, Amit Bandyopadhyay
    Abstract:

    Abstract Surface modification of AISI 410 martensitic stainless steel was carried out by laser surface-melting using laser engineered net shaping (LENSTM). The Microstructures of laser surface-melted specimens showed varying amount of retained austenite depending on the processing parameters. The refinement and high strength of austenite as a result of increased scan speed and decreased laser power resulted in high amount of retained austenite in the Final Microstructure. Laser surface-melting of AISI 410 martensitic stainless steel at optimized processing parameters resulted in fine martensite with minimum retained austenite, leading to a 55% increase in the surface hardness compared to the hardness of conventionally heat treated samples. The inherent advantage of laser surface-melting using LENSTM is to control simultaneously both location and Microstructure leading to better service performance of components.

  • surface modification of aisi 410 stainless steel using laser engineered net shaping lenstm
    Materials & Design, 2009
    Co-Authors: Vamsi B Krishna, Amit Bandyopadhyay
    Abstract:

    Abstract Surface modification of AISI 410 martensitic stainless steel was carried out by laser surface-melting using laser engineered net shaping (LENSTM). The Microstructures of laser surface-melted specimens showed varying amount of retained austenite depending on the processing parameters. The refinement and high strength of austenite as a result of increased scan speed and decreased laser power resulted in high amount of retained austenite in the Final Microstructure. Laser surface-melting of AISI 410 martensitic stainless steel at optimized processing parameters resulted in fine martensite with minimum retained austenite, leading to a 55% increase in the surface hardness compared to the hardness of conventionally heat treated samples. The inherent advantage of laser surface-melting using LENSTM is to control simultaneously both location and Microstructure leading to better service performance of components.

Marcel Ausloos - One of the best experts on this subject based on the ideXlab platform.

  • from re 211 to re 123 how to control the Final Microstructure of superconducting single domains
    Superconductor Science and Technology, 2005
    Co-Authors: Rudi Cloots, T Koutzarova, J P Mathieu, Marcel Ausloos
    Abstract:

    This paper reviews the usual techniques for producing YBCO-type single-domains and the Microstructure of the as-obtained samples. The problems of seed dissolution and parasite nucleations are discussed in detail. The formation of microstructural defects, such as pores and cracks, is examined. An important part of this review is devoted to the study of the influence of RE-211 particles (RE2BaCuO5 where RE denotes Y, Yb, Nd, Sm, Dy, Gd, Eu or a mixture of them. Generally Nd4Ba2Cu2O10 is preferred to Nd2BaCuO5) for the Microstructure and properties of RE?Ba?Cu?O single-domains. Pushing/trapping theory is described in order to explain the spatial distribution of RE-211 particles in the RE-123 ((RE)Ba2Cu3O7??) monoliths. The formation of RE-211-free regions is discussed. Different ways to limit the RE-211 coarsening are reviewed. Microstructural defects in the RE-123 matrix caused by the RE-211 particles are presented. It is also shown that RE-211 particles play a significant role in the mechanical properties of single-domain samples. We finish this review by discussing the infiltration and growth process as a good technique to control the Microstructure.

  • from re 211 to re 123 how to control the Final Microstructure of superconducting single domains
    arXiv: Superconductivity, 2004
    Co-Authors: Rudi Cloots, T Koutzarova, J P Mathieu, Marcel Ausloos
    Abstract:

    This paper reviews the usual techniques for producing YBCO-type single-domains and the Microstructure of the as-obtained samples. The problems of seed dissolution and parasite nucleations are discussed in details. Formation of microstructural defects, such as pores and cracks, are examined. An important part of this review is devoted to the study of the influence of RE-211 particles [RE2BaCuO5 where RE denotes Y, Yb, Nd, Sm, Dy, Gd, Eu or a mixture of them. Generally Nd4Ba2Cu2O10 is preferred to Nd2BaCuO5] on the Microstructure and properties of RE-Ba-Cu-O single-domains. Trapping/Pushing theory is described in order to explain the spatial distribution of RE-211 particles in the RE-123 [(RE)Ba2Cu3O7-d] monoliths. Formation of RE-211-free regions is discussed. Different ways to limit the RE-211 coarsening are reviewed. Microstructural defects in the RE-123 matrix caused by the RE-211 particles are presented. It is also shown that RE-211 particles play a significant role on the mechanical properties of single-domain samples. We finish this review by discussing the Infiltration and Growth process as a good technique to control the Microstructure.

Elena V Pereloma - One of the best experts on this subject based on the ideXlab platform.

  • transformation behaviour in thermomechanically processed c mn si trip steels with and without nb
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999
    Co-Authors: Elena V Pereloma, Ilana Timokhina, Peter Hodgson
    Abstract:

    Abstract Two 0.2wt.% C–1.55wt.% Mn–1.5wt.% Si steels with and without the addition of 0.039 wt.% Nb were studied by laboratory simulations of controlled thermomechanical processing in a quench deformation dilatometer. The Microstructures were characterised using optical metallography, image analysis and scanning electron microscopy techniques. The effects of recrystallised and non-recrystallised austenite and discontinuous paths on the Final Microstructure were studied. The results have shown that the highest volume fraction of retained austenite is associated with a 400°C isothermal bainite transformation temperature and the presence of approximately 50% polygonal ferrite and acicular ferrite as a dominant second phase.

  • the effect of transformation path on the Final Microstructure of high and low silicon 0 1 wt c steels
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1998
    Co-Authors: Elena V Pereloma, Peter Hodgson
    Abstract:

    Two low-carbon steels with low (0.16 wt.%) and high (1.4 wt.%) Si contents were studied using laboratory simulations of thermomechanically controlled processing. Continuous cooling and discontinuous cooling schedules were utilised to evaluate the transformation behaviour of these steels. It has been found that both the transformation history and the state of austenite prior to transformation have a significant effect on the Final Microstructure. Both the prior austenite condition and the amount of ferrite prior to a change in cooling rate influence the morphology of second phase. The results have shown that to predict the Final Microstructure and mechanical properties it is not sufficient to model the process based only on average austenite composition and solute partitioning during austenite decomposition.