Effect of Heat Treatment Process on Mechanical Properties of High Chromium Low Activated Ferritic-martensitic Steel

Abstract

Ferritic-martensitic steel is a kind of steel with excellent anti-radiation properties， which is one of superior candidate materials for structural components of the new generation of nuclear reactors with high radiation doses. The harsh service environment requires that ferritic-martensitic steel has good comprehensive mechanical properties， suitable grain size and few internal defects. In this paper， the effects of normalizing and tempering heat treatment on mechanical properties and microstructure evolution of new composition ferritic-martensitic steel were studied. At the same time， the ThermoCalc software is used to calculate the volume proportion of different phase states and compare it with the experimental results， it finds that the calculated results of the two-phase ratio change are highly consistent with the experimental results.After normalizing treatment， the tensile strength and yield strength of the material are mainly affected by the ratio of two phases. The results show high-martensitic steel treated with 1 080 ℃ normalizing + 670 ℃ tempering heat has a tensile strength of 903 MPa and yield strength of 732 MPa， showing the best comprehensive performance of the materials.

Keywords

• ferritic-martensitic steel； yield strength， normalizing； tempering； m23c6； thermodynamic calculation