Back stress work hardening confirmed by Bauschinger effect in a TRIP steel using bending tests

Martensite formed in TRIP steels causes large work hardening. The expectation that this is due to the back stresses induced into the ferrite by the hard martensite was examined by the Bauschinger effect after room temperature tensile straining of a TRIP steel into which the martensite had been introduced by prior straining at –50°C. Bending tests were employed to detect the Bauschinger effect. The tests showed that the compressive flow stress became much smaller than the tensile flow stress and confirmed the expectation