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B.k. Choudhary - One of the best experts on this subject based on the ideXlab platform.
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Unified description of tensile work hardening behaviour of P92 steel
Materials Science and Engineering: A, 2016Co-Authors: E. Isaac Samuel, J. Christopher, G. Sainath, B.k. ChoudharyAbstract:Abstract Tensile work hardening behaviour of P92 steel has been examined over wide range of temperatures (300–923 K) and Strain Rates (3.16×10 −5 –1.26×10 −3 s −1 ) in terms of the variations of instantaneous work hardening Rate ( θ ) with true stress ( σ ) and true Plastic Strain Rate ( e p ). At all the temperatures and applied Strain Rates, θ vs. σ exhibited two-stage work hardening behaviour characterised by a rapid decrease in θ at low stresses (transient stage) followed by a gradual decrease at high stresses (stage-III). θ vs. σ also exhibited three distinct temperature regimes along with signatures of dynamic Strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures. Analysis in terms of the variations of θ with e p displayed a unified curvilinear behaviour independent of temperature. For a given applied Strain Rate, a linear correlation between θ and the reciprocal of Plastic Strain Rate (1/ e p ) was observed. As a consequence, the Rate of change of true stress was observed to be directly proportional to Plastic Strain Rate independent of temperature. Further, a unified description of tensile work hardening in terms of a master curve between work hardening Rate ( θ ) and Plastic Strain Rate normalised by applied Strain Rate ( e p / e a ) has been obtained for the range of Strain Rates and temperatures examined.
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Unified Tensile Work Hardening Behaviour of Thin Section Plate and Forged Thick Section 9Cr-1Mo Ferritic Steel
High Temperature Materials and Processes, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, J. Christopher, D.p. Rao Palaparti, M.d. MathewAbstract:AbstractDetailed investigation has been performed on tensile work hardening behaviour in terms of the variations of instantaneous work hardening Rate (θ = dσ/dεp, where σ is true stress and εp is true Plastic Strain) with stress and true Plastic Strain Rate (ε̇p) for temperature range 300–873 K in two different material conditions, (i) normalised and tempered plate and (ii) quenched and tempered tubeplate forging of 9Cr-1Mo ferritic steel. Both plate and tubeplate forging exhibited two-stage work hardening and three different temperature regimes in the variation of θ with σ. The variations of θ with respect to ε̇p exhibited unified work hardening in terms of a single master curve independent of temperature and initial microstructure. θ varied linearly with reciprocal of Plastic Strain Rate, i.e. 1/ε̇p, and as a consequence, linear correlation between the Rate of change of true stress and true Plastic Strain Rate independent of temperature and microstructure has been obtained.
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Unified tensile work hardening behaviour of 9Cr-1Mo ferritic steel
Materials Science and Technology, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, D.p. Rao Palaparti, T. JayakumarAbstract:Tensile work hardening behaviour of 9Cr–1Mo ferritic steel has been examined in terms of the variations in instantaneous work hardening Rate (θ = dσ/dϵp, where σ is true stress and ϵp is true Plastic Strain) with stress and Plastic Strain Rate for a wide range of temperatures (300–873 K) and Strain Rates (6·33×10−5–6·33×10−3 s−1). Both θ–σ and θσ–σ exhibited two stage work hardening behaviour and distinct three temperature regimes with signatures of dynamic Strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. The variations in θ with for 300–873 K exhibited unified work hardening in terms of sepaRate master curves for different Strain Rates. At all the Strain Rates, θ varied linearly with reciprocal of Plastic Strain Rate independent of temperature. As a consequence, direct proportionality between Rate of change in true stress and Plastic Strain Rate is obtained.
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Tensile work hardening behaviour of P91 steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: E. Isaac Samuel, B.k. ChoudharyAbstract:Abstract The variation of instantaneous work hardening Rate ( θ ) with Plastic Strain Rate ( e ˙ p ) for P91 steel indicated that θ – e ˙ p plots can be represented by a single master curve for the temperature range 300–873 K. A linear correlation between θ and reciprocal of Plastic Strain Rate ( 1 / e ˙ p ) independent of temperature is obtained.
E. Isaac Samuel - One of the best experts on this subject based on the ideXlab platform.
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Unified description of tensile work hardening behaviour of P92 steel
Materials Science and Engineering: A, 2016Co-Authors: E. Isaac Samuel, J. Christopher, G. Sainath, B.k. ChoudharyAbstract:Abstract Tensile work hardening behaviour of P92 steel has been examined over wide range of temperatures (300–923 K) and Strain Rates (3.16×10 −5 –1.26×10 −3 s −1 ) in terms of the variations of instantaneous work hardening Rate ( θ ) with true stress ( σ ) and true Plastic Strain Rate ( e p ). At all the temperatures and applied Strain Rates, θ vs. σ exhibited two-stage work hardening behaviour characterised by a rapid decrease in θ at low stresses (transient stage) followed by a gradual decrease at high stresses (stage-III). θ vs. σ also exhibited three distinct temperature regimes along with signatures of dynamic Strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures. Analysis in terms of the variations of θ with e p displayed a unified curvilinear behaviour independent of temperature. For a given applied Strain Rate, a linear correlation between θ and the reciprocal of Plastic Strain Rate (1/ e p ) was observed. As a consequence, the Rate of change of true stress was observed to be directly proportional to Plastic Strain Rate independent of temperature. Further, a unified description of tensile work hardening in terms of a master curve between work hardening Rate ( θ ) and Plastic Strain Rate normalised by applied Strain Rate ( e p / e a ) has been obtained for the range of Strain Rates and temperatures examined.
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Unified Tensile Work Hardening Behaviour of Thin Section Plate and Forged Thick Section 9Cr-1Mo Ferritic Steel
High Temperature Materials and Processes, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, J. Christopher, D.p. Rao Palaparti, M.d. MathewAbstract:AbstractDetailed investigation has been performed on tensile work hardening behaviour in terms of the variations of instantaneous work hardening Rate (θ = dσ/dεp, where σ is true stress and εp is true Plastic Strain) with stress and true Plastic Strain Rate (ε̇p) for temperature range 300–873 K in two different material conditions, (i) normalised and tempered plate and (ii) quenched and tempered tubeplate forging of 9Cr-1Mo ferritic steel. Both plate and tubeplate forging exhibited two-stage work hardening and three different temperature regimes in the variation of θ with σ. The variations of θ with respect to ε̇p exhibited unified work hardening in terms of a single master curve independent of temperature and initial microstructure. θ varied linearly with reciprocal of Plastic Strain Rate, i.e. 1/ε̇p, and as a consequence, linear correlation between the Rate of change of true stress and true Plastic Strain Rate independent of temperature and microstructure has been obtained.
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Unified tensile work hardening behaviour of 9Cr-1Mo ferritic steel
Materials Science and Technology, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, D.p. Rao Palaparti, T. JayakumarAbstract:Tensile work hardening behaviour of 9Cr–1Mo ferritic steel has been examined in terms of the variations in instantaneous work hardening Rate (θ = dσ/dϵp, where σ is true stress and ϵp is true Plastic Strain) with stress and Plastic Strain Rate for a wide range of temperatures (300–873 K) and Strain Rates (6·33×10−5–6·33×10−3 s−1). Both θ–σ and θσ–σ exhibited two stage work hardening behaviour and distinct three temperature regimes with signatures of dynamic Strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. The variations in θ with for 300–873 K exhibited unified work hardening in terms of sepaRate master curves for different Strain Rates. At all the Strain Rates, θ varied linearly with reciprocal of Plastic Strain Rate independent of temperature. As a consequence, direct proportionality between Rate of change in true stress and Plastic Strain Rate is obtained.
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Tensile work hardening behaviour of P91 steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: E. Isaac Samuel, B.k. ChoudharyAbstract:Abstract The variation of instantaneous work hardening Rate ( θ ) with Plastic Strain Rate ( e ˙ p ) for P91 steel indicated that θ – e ˙ p plots can be represented by a single master curve for the temperature range 300–873 K. A linear correlation between θ and reciprocal of Plastic Strain Rate ( 1 / e ˙ p ) independent of temperature is obtained.
T. Jayakumar - One of the best experts on this subject based on the ideXlab platform.
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Unified tensile work hardening behaviour of 9Cr-1Mo ferritic steel
Materials Science and Technology, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, D.p. Rao Palaparti, T. JayakumarAbstract:Tensile work hardening behaviour of 9Cr–1Mo ferritic steel has been examined in terms of the variations in instantaneous work hardening Rate (θ = dσ/dϵp, where σ is true stress and ϵp is true Plastic Strain) with stress and Plastic Strain Rate for a wide range of temperatures (300–873 K) and Strain Rates (6·33×10−5–6·33×10−3 s−1). Both θ–σ and θσ–σ exhibited two stage work hardening behaviour and distinct three temperature regimes with signatures of dynamic Strain aging at intermediate temperatures and dominance of dynamic recovery at high temperatures. The variations in θ with for 300–873 K exhibited unified work hardening in terms of sepaRate master curves for different Strain Rates. At all the Strain Rates, θ varied linearly with reciprocal of Plastic Strain Rate independent of temperature. As a consequence, direct proportionality between Rate of change in true stress and Plastic Strain Rate is obtained.
Frédéric Barlat - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Plastic Strain Rate under Strain path changes in dual-phase steel using microstructure-based modeling
International Journal of Plasticity, 2017Co-Authors: Jinwoo Lee, Myoung Gyu Lee, Ji Hoon Kim, Frédéric BarlatAbstract:Micromechanical-based finite element simulations were carried out to investigate the transient Plastic Strain Rate evolutions of ferrite and martensite dual-phase steel during Strain path changes. A representative volume element (RVE) was geneRated through a three-dimensional (3D) reconstruction of microstructure images which were acquired from sequential polishing of a small material volume. The 10 × 10 × 10 μm3 3D RVEs consisted of martensite islands embedded in a ferrite base matrix. Each phase was assumed to exhibit distinct mechanical properties but the grain and phase boundary effects were ignored in this work. The effective mechanical properties for the constituent phases were assumed to be well defined by the von Mises or Hill 1948 yield criteria, the associated flow rule, and an empirical isotropic hardening equation based on chemical composition. This model was applied to investigate the transient behavior of the r-value (Lankford coefficient) in uniaxial tension when the loading direction changed. In addition to monotonic tension, compression-tension, and tension-orthogonal tension, sequences were considered. The simulation results captured well in a qualitative manner the experimental r-value evolutions in terms of a temporary transition and asymptotic limit. The evolutions of stress states in ferrite and martensite were analyzed to explain the r-value behavior that resulted from three factors: (1) r-value differences between ferrite and martensite, (2) martensite configuration-induced stress state in phases, and (3) stress partitioning and its evolution during non-proportional loading. Finally, an analytical relationship between the stress evolution in the constituent phases and the relevant r-value changes is suggested.
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ORTHOTROPIC Strain Rate POTENTIALS USING MULTIPLE LINEAR TRANSFORMATIONS
International Journal of Solids and Structures, 2009Co-Authors: Meziane Rabahallah, Tudor Balan, Frédéric BarlatAbstract:This paper reviews a class of anisotropic Plastic Strain-Rate potentials, based on linear transformations of the Plastic Strain-Rate tensor. A new formulation is proposed, which includes former models as particular cases and allows for an arbitrary number of linear transformations, involving an increasing number of anisotropy parameters. The formulation is convex and fully three-dimensional, thus being suitable for computer implementation in finite element codes. The parameter identification procedure uses a micromechanical model to geneRate evenly distributed reference points in the full space of possible loading modes. Material parameters are determined for several anisotropic, fcc and bcc sheet metals, and the gain in accuracy of the new models is demonstRated. For the considered materials, increasing the number of linear transformations leads to a systematic improvement of the accuracy, up to a number of five linear transformations. The proposed model fits very closely the predictions of the micromechanical model in the whole space of Plastic Strain-Rate directions. The r-values, which are not directly used in the identification procedure, served for the validation of the models and to demonstRate their improved accuracy.
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Application of Strain Rate potentials with multiple linear transformations to the description of polycrystal Plasticity
International Journal of Solids and Structures, 2009Co-Authors: Meziane Rabahallah, Tudor Balan, Frédéric BarlatAbstract:This paper reviews a class of anisotropic Plastic Strain-Rate potentials, based on linear transformations of the Plastic Strain-Rate tensor. A new formulation is proposed, which includes former models as particular cases and allows for an arbitrary number of linear transformations, involving an increasing number of anisotropy parameters. The formulation is convex and fully three-dimensional, thus being suitable for computer implementation in finite element codes. The parameter identification procedure uses a micromechanical model to geneRate evenly distributed reference points in the full space of possible loading modes. Material parameters are determined for several anisotropic, fcc and bcc sheet metals, and the gain in accuracy of the new models is demonstRated. For the considered materials, increasing the number of linear transformations leads to a systematic improvement of the accuracy, up to a number of five linear transformations. The proposed model fits very closely the predictions of the micromechanical model in the whole space of Plastic Strain-Rate directions. The r-values, which are not directly used in the identification procedure, served for the validation of the models and to demonstRate their improved accuracy.
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Parameter identification of advanced Plastic Strain Rate potentials and impact on Plastic anisotropy prediction
International Journal of Plasticity, 2009Co-Authors: Meziane Rabahallah, Tudor Balan, Frédéric Barlat, Salima Bouvier, Kwansoo Chung, Brigitte Bacroix, Cristian TeodosiuAbstract:In the work presented in this paper, several Strain Rate potentials are examined in order to analyze their ability to model the initial stress and Strain anisotropy of several orthotropic sheet materials. Classical quadratic and more advanced non-quadratic Strain Rate potentials are investigated in the case of FCC and BCC polycrystals. Different identifications procedures are proposed, which are taking into account the crystallographic texture and/or a set of mechanical test data in the determination of the material parameters.
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An elasto-Plastic constitutive model with Plastic Strain Rate potentials for anisotropic cubic metals
International Journal of Plasticity, 2008Co-Authors: Ji Hoon Kim, Frédéric Barlat, Myoung Gyu Lee, Robert H. Wagoner, Kwansoo ChungAbstract:An elasto-Plastic constitutive model with the Plastic Strain Rate potential was developed for finite element analysis. In the model, isotropic-kinematic hardening was incorpoRated under the plane stress condition for anisotropic sheet cubic metal forming analysis. The formulation is general enough for any homogeneous Plastic Strain Rate potential (with the first-order homogeneous effective Strain Rate) but the Plastic Strain Rate potential Srp2004-18p was considered here. Attention was focused on the development of the elasto-Plastic transition criterion and the effective stress update algorithm. Also, to assure the quadratic convergence Rate in Newton’s method, the elasto-Plastic tangent modulus was analytically derived. Accuracy and convergence of the stress update algorithm were assessed by the iso-error maps, whereas stability of the algorithm was confirmed by analytical procedure. Validations were performed for the examples of the circular cup drawing, 2D draw-bending and unconStrained cylindrical bending tests, utilizing aluminum sheet alloys.
J. Christopher - One of the best experts on this subject based on the ideXlab platform.
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Unified description of tensile work hardening behaviour of P92 steel
Materials Science and Engineering: A, 2016Co-Authors: E. Isaac Samuel, J. Christopher, G. Sainath, B.k. ChoudharyAbstract:Abstract Tensile work hardening behaviour of P92 steel has been examined over wide range of temperatures (300–923 K) and Strain Rates (3.16×10 −5 –1.26×10 −3 s −1 ) in terms of the variations of instantaneous work hardening Rate ( θ ) with true stress ( σ ) and true Plastic Strain Rate ( e p ). At all the temperatures and applied Strain Rates, θ vs. σ exhibited two-stage work hardening behaviour characterised by a rapid decrease in θ at low stresses (transient stage) followed by a gradual decrease at high stresses (stage-III). θ vs. σ also exhibited three distinct temperature regimes along with signatures of dynamic Strain ageing at intermediate temperatures and dominance of dynamic recovery at high temperatures. Analysis in terms of the variations of θ with e p displayed a unified curvilinear behaviour independent of temperature. For a given applied Strain Rate, a linear correlation between θ and the reciprocal of Plastic Strain Rate (1/ e p ) was observed. As a consequence, the Rate of change of true stress was observed to be directly proportional to Plastic Strain Rate independent of temperature. Further, a unified description of tensile work hardening in terms of a master curve between work hardening Rate ( θ ) and Plastic Strain Rate normalised by applied Strain Rate ( e p / e a ) has been obtained for the range of Strain Rates and temperatures examined.
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Unified Tensile Work Hardening Behaviour of Thin Section Plate and Forged Thick Section 9Cr-1Mo Ferritic Steel
High Temperature Materials and Processes, 2013Co-Authors: B.k. Choudhary, E. Isaac Samuel, J. Christopher, D.p. Rao Palaparti, M.d. MathewAbstract:AbstractDetailed investigation has been performed on tensile work hardening behaviour in terms of the variations of instantaneous work hardening Rate (θ = dσ/dεp, where σ is true stress and εp is true Plastic Strain) with stress and true Plastic Strain Rate (ε̇p) for temperature range 300–873 K in two different material conditions, (i) normalised and tempered plate and (ii) quenched and tempered tubeplate forging of 9Cr-1Mo ferritic steel. Both plate and tubeplate forging exhibited two-stage work hardening and three different temperature regimes in the variation of θ with σ. The variations of θ with respect to ε̇p exhibited unified work hardening in terms of a single master curve independent of temperature and initial microstructure. θ varied linearly with reciprocal of Plastic Strain Rate, i.e. 1/ε̇p, and as a consequence, linear correlation between the Rate of change of true stress and true Plastic Strain Rate independent of temperature and microstructure has been obtained.