Phenomenological Modeling of Deformation-Induced Martensite Transformation Kinetics in Austenitic Stainless Steels

The aim of this study is to predict the kinetics of deformation-induced martensite transformation (DIMT) by proposing a novel model considering the effects of three loading characteristics: temperature, strain rate, and stress state. Experiments including hot compression, tension, notched tension, and shear tests using 304 stainless steel plate were carried out to investigate the transformation kinetics. After a decoupling analysis was conducted on the effects of the three characteristics, particularly the temperature and strain rate effects under high strain rate loading conditions, three kinetic sub-models were established individually for each effect, and the proposed model was developed by multiplying the three kinetic sub-models. A stepwise fitting method was proposed for the calibration of material constants to replace complex iterative optimization algorithms and improve the certainty of the values of the material constants. The proposed model was further validated using the experimental data of various austenitic stainless steels obtained from previous studies. Result shows the model revealed satisfactory accuracy in predicting the DIMT behavior in material experiment. After compiling the model into a USDFLD subroutine, simulation of a heat-assisted fine-blanking process was conducted in ABAQUS, giving a reasonable prediction of martensite content of the blanking parts.