I. Hajiannia - Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran
R. Ashiri - Department of Materials Science and Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran
M. R. Pakmanesh - Iran Institutes of Materials and Energy, Iranian Space Research Center, Isfahan, Iran
M. Shamanian - Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran

In this research, ultrahigh strength transformation induced plasticity-assisted steel (TRIP-assisted steel) was developed to be used in the automobile body. For this, it is essential to characterize its weldability in resistance spot welding process. Therefore, the resistance spot welding metallurgy and weldability of the steel under different welding parameters are studied.  the desired sample was studied in two states with higher pressure and less time. The results are presented following the most important advantage of the current steel in contrast to the similar steels is its excellent weldability enabling its application in the auto pillar. The microstructure and mechanical properties of TRIP steel spot welds were characterized using metallurgical techniques, lap shear tensile tests fractography and microhardness testing methods. Failure mode transition from interfacial to pullout failure mode was achieved for sample 10kA with 4kN. Partial interfacial failure was removed after nugget size increased. Pullout failure mode is seen for the sample 2, 10kA with 3.5kN.

TRIP Steel, Resistance Spot Welding, mechanical properties, Failure Mode