A computational model for the prediction of steel hardenability

A computational model is presented in this article for the prediction of microstructural development during heat treating of steels and resultant room-temperature hardness. This model was applied in this study to predict the hardness distribution in end-quench bars (Jominy hardness) of heat treatable steels. It consists of a thermodynamics model for the computation of equilibria in multicomponent Fe-C-M systems, a finite element model to simulate the heat transfer induced by end quenching of Jominy bars, and a reaction kinetics model for austenite decomposition. The overall methodology used in this study was similar to the one in the original work of Kirkaldy. Significant efforts were made to reconstitute the reaction kinetics model for austenite decomposition in order to better correlate the phase transformation theory with empiricism and to allow correct phase transformation predictions under continuous cooling conditions. The present model also expanded the applicable chemical composition range. The predictions given by the present model were found to be in good agreement with experimental measurements and showed considerable improvement over the original model developed by Kirkaldy et al.

[1]  J. Kirkaldy,et al.  Prediction of the equilibrium, paraequilibrium and no-partition local equilibrium phase diagrams for multicomponent Fe-C base alloys , 1984 .

[2]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[3]  J. S. Kirkaldy,et al.  Thermodynamic prediction of the ae3 temperature of steels with additions of Mn, Si, Ni, Cr, Mo, Cu , 1978 .

[4]  M. Hillert,et al.  The Regular Solution Model for Stoichiometric Phases and Ionic Melts. , 1970 .

[5]  M. Avrami Kinetics of Phase Change. I General Theory , 1939 .

[6]  John W. Cahn,et al.  The kinetics of grain boundary nucleated reactions , 1956 .

[7]  J. S. Kirkaldy,et al.  Optimization of steel hardenability control , 1989 .

[8]  C. Kung,et al.  An examination of the validity of existing empirical formulae for the calculation of ms temperature , 1982 .

[9]  V. Voort,et al.  Atlas of time-temperature diagrams for irons and steels , 1991 .

[10]  R. J. Goldstein,et al.  Natural convection mass transfer adjacent to horizontal plates , 1973 .

[11]  C. Wagner Thermodynamics of alloys , 1952 .

[12]  A. Chapman Fundamentals of heat transfer , 1987 .

[13]  Douglas V. Doane,et al.  Hardenability concepts with applications to steel , 1978 .

[14]  S. Churchill,et al.  Correlating equations for laminar and turbulent free convection from a vertical plate , 1975 .

[15]  J. Kirkaldy,et al.  Computed multicomponent phase diagrams for hardenability (H) and HSLA steels with application to the prediction of microstructure and mechanical properties , 1993 .

[16]  J. S. Kirkaldy,et al.  Diffusion-controlled phase transformations in steels. Theory and applications , 1991 .

[17]  M. Atkins,et al.  Atlas of Continuous Cooling Transformation Diagrams for Engineering Steels , 1980 .

[18]  C. J. Smithells,et al.  Smithells metals reference book , 1949 .