Low Transverse Ductility in a New High-Strength Corrosion-Resistant Steel: Microstructure and Texture

Abstract

Development of ultrahigh-strength steels having optimum combination of high ultimate tensile strength, fracture toughness and corrosion resistance has gained much importance due to emerging applications in the aerospace, medical and automobile industries. Indigenous development program of such steel has been started in India. Initial heats have been prepared following the standard processing route, and it was found that while they showed very high strength (1725–1757 MPa), ductility in the transverse direction (13–32% reduction in area) was lower than specification (minimum 35% reduction in area). Poor texture was initially believed to be the possible reason for this low transverse ductility. Hence, investigative characterization work was taken up to understand this effect in different heats of Aerospace Material Specification (AMS5936 C) steel samples. In this paper, it would be conclusively discussed how microstructural inhomogeneity and the presence of inclusions became overpowering reasons for poor transverse ductility as compared with the textural reasons in indigenous material.