Magnetic Evaluation of Tensile Deformation Behaviour of TRIP Assisted Steels

Two grades (690 and 980 MPa) of Transformation Induced Plasticity (TRIP) assisted steels were tensile-deformed to various strain levels to find the effect of tensile deformation on the mechanical properties of the steels. Brinell hardness was measured to find the hardening behaviour of the tensile-deformed steels. Magnetic Barkhausen Emissions (MBE) and magnetic hysteresis loop measurements were carried out on the specimens for the correlation of magnetic properties with the mechanical properties of the steels for their non-destructive magnetic evaluations. Coercivity and hardness were found to increase with the increase in plastic strain indicating work hardening of the steels whereas a continuous decrease in Root Mean Square (RMS) voltage of the MBE was found after an early increase. The early increase in RMS voltage of the MBE is due to the stress relaxation effect on the early stage of plastic deformation. A strong correlation was found between the coercivity and hardness of the steels indicating the potential application of the magnetic technique for the non-destructive evaluation of deformation behaviour of TRIP steels.