Strength of mixtures of bainite and martensite

TLDR

Recently published experimental data demonstrate that the strength of mixed microstructures of tempered bainite and martensite can peak at an intermediate volume fraction of martensite. The study aims to quantitatively interpret this observed peak strength by modeling the mechanical properties of tempered bainite and martensite. The model incorporates bainite’s enrichment of residual austenite with carbon, which increases martensite strength, and the plastic constraint that enhances bainite strength by surrounding martensite. The peak strength is attributed to these two effects, and the model accurately predicts both the trends and absolute values of published experimental data.

Abstract

AbstractAbstractRecently published experimental data demonstrate that the strength of mixed microstructures of tempered bainite and martensite can peak at an intermediate volume fraction of martensite. In the present work, a quantitative interpretation of these observations is achieved by modelling the mechanical properties of bainite and martensite in their tempered states. It is found that the peak in the curve of the strength as a function of the volume fraction of martensite can be attributed to two factors. When bainite forms it enriches the residual austenite with carbon, so that the strength of the subsequent martensite increases. In addition, during its deformation, the strength of the bainite is enhanced via plastic constraint by the surrounding stronger martensite. Taking these effects into account, it is possible to predict accurately both the trends and the absolute values of published experimental data on the strength of mixed microstructures.MST/1901