A method for the determination of individual phase properties in multiphase steels

A method is proposed to determine the accurate constitutive model of individual phase in multiphase steel with small phase size. The nanoindentation tests with continuous stiffness method (CSM) were implemented to obtain the hardness-displacement curves of the advanced high strength steel DP1180. The validity of the nanoindentation results was evaluated based on the EBSD results and classic indentation size effect (ISE) model. The extra loading of loading-displacement curves due to geometrically necessary dislocations (GNDs) was excluded based on the simple established model. The constitutive model of each phase was determined based on the corrected loading-displacement curves using the inversion method. The results of microstructure based simulation agree well with those of tensile tests, which proves the reliability and accuracy of the constitutive model of individual phase obtained from the method proposed in this study.