Improvement of Mechanical Properties of a Medium-Mn TRIP Steel by Precursor Microstructure Control

摘要

An approach of optimizing the intercritical annealing path in a 0.2C-5Mn medium-Mn steel is presented by introducing precursor microstructure prior to normal austenite reverted transformation(ART)annealing.The steel is fi rstly pre-annealed at diff erent intercritical temperatures to form designed precursor microstructures.Then,they are employed for subsequent conventional ART annealing processing.It is found that pre-annealing at relative high intercritical temperatures can promote precipitation and dissolution of the carbide in the steel and re-distribute the C and Mn in the microstructures.The produced microstructural precursors show excellent merits in accelerating the austenite reversions in subsequent normal ART processing and assisting the RA formation.Tensile testing reveals that the excellent strength-elongation balance can be achieved in the heat-treated samples using diff erent microstructural precursors,which suggests the potential applicability in producing the medium-Mn steels with shortened processing period.