Study on Microstructure and Properties of High-Martensite Dual-Phase Steel

The microstructure,tensile properties as well as fracture mechanism of high-martensite content dual-phase steel were studied by OM,SEM and tension test.Results show that with the increase of intercritical quenching temperature in(α+γ) range,the volume fraction of martensite continuously rises,enhanceing the strength of the steel.In addition,the volume fraction of martensite exhibits a certain influence on transformsation from ductile to brittle fracture.Finally,microscopic holes are formed near the fracture surface,the morphology of which is changed with the increase of volume fraction of martensite.