Research and Development of 780MPa grade low-density steels

Abstract

In order to meet the weight reduction of automotive body, low density steels containing about 4wt.% of Al have been newly developed. The microstructure of low-density steel, comprising a mixture of blocky retained austenite, bainite, δ-ferrite and α-ferrite, was produced using a laboratory annealing simulator. The low-density steel exhibits good combination of strength and ductility, whose properties shows tensile strength of 810MPa with elongation of 27.4%. Its extraordinary properties are obtained from δ-ferrite and austenite deformation induced martensite.