Dual-phase steels with low manganese content. Structures and mechanical properties

Abstract

This article are presented the results of studies conducted to determine the influence of the intercritical heating temperature on the structure and mechanical properties of the dual-phase steels with low manganese content (0,511% Mn, respectively 0,529% Mn). The ferrite-martensitic structures, specific for dual-phase steels, were obtained by intercritical quenching, which consisted of heating the samples to temperatures located between critical points Ac1 and Ac3 (760, 780, 800, and 820°C), followed by cooling in water. With the help of metallographic analyses, the volume fraction of martensite and ferrite microhardness from the structures were determined, and by tensile testing, the ultimate tensile strength and the total elongation were established. The results obtained for the two dual-phase steels with low manganese content were compared with those determined in previous research, performed on a dual-phase steel with 1.90% Mn.