STUDY OF MICROSTRUCTURES BETWEEN CONTINUOUS ANNEALED SHEET AND HOT DIP GALVANIZED SHEET OF 600MPA HIGH ALUMINUM DUAL PHASE STEEL(153)

摘要

In this paper the difference between the microstructures of the continuous annealed sheetand the hot dip galvanized sheet of the high aluminum dual phase steel had been studied.The difference of the processing route resulted in the difference of the microstructures soas to the mechanical properties of both steel. The microstructures of the continuousannealed steel were ferrite and 14%~17% martensites which dispersed like island aroundthe ferrite grain boundaries, and there exists lots of high density dislocation in ferrite andobvious twinning structures in martensite. The microstructures of hot dip galvanized steelwere ferrite and 8%~11% martensite and bainte as well as 4~6% retained austenites. Theexistence of more high density dislocation in ferrite and more martensites made thecontinuous annealed steel deliver a higher tensile strength and a lower yield strength, andthe existence of bainite and fine pealite in martensite as well as less martensite made thegalvanized steel deliver a higher yield strength and the retained austenites help thegalvanized steel exhibit much higher elongation.