Comparison of Work Hardening Behaviour of Ferritic-Bainitic and Ferritic-Martensitic Dual Phase Steels

Abstract

In this research, the stress-strain curves of two types of dual phase steels, namely ferritic-bainitic and ferritic-martensitic steels with 0.16%C and 1.2% Mn have been obtained using tensile tests. Both steels were intercritically annealed under different conditions and the ferritic bainitic steels subsequently quenched in a salt bath, while the ferritic martensitic steels were water quenched. The stress-strain data of the specimens were checked using Hollomon's equation. The results showed that both types of dual phase steels had two stages of work hardening and each stage had a different work hardening exponent. The effects of volume fraction of hard phases (bainite and martensite) on ultimate tensile strength, total elongation and work hardening exponent were also investigated. The results indicated that with increasing volume fraction of hard phase the UTS was increased whereas the work hardening exponent and total elongation were decreased.