Quantitative description of dual-phase steel microstructure
Abstract
The effect ofprior cold working on dual-phase steel C-Mn-Si-V type microstructure was analysed with an application of quantitative metallography and statistical methods. The paper includes a proposal of terminology and notation unification of stereological parameters. Some improvements and supplements of dual-phase (D-P) steel microstructure description are suggested. The diagrams and empirical quations showing the effect of prior cold work ratio on volume fraction, size, shape and distribution of phases are presented. The main conclusion drawn from the performed investigations is that the magnitude of prior cold working significantly affects size and shape distributions of both ferritic grains and martensitic islands as well as the inhomogeneity of martensitic islands distribution. It was found that prior cold work ratio of 65-75%, leading to the significant refinement of microstructure and its homogenization, ensures the best combination of D-P steel strength and ductility.