Title of article :
The Assessment of Second Pulse Effects on the Microstructure and Fracture Behavior of the Resistance Spot Welding in Advanced Ultrahigh-Strength Steel TRIP1100
Author/Authors :
Hajiannia, I i.hajiannia@ma.iut.ac.ir , Shamanian, M Department of Materials Engineering - Isfahan University of Technology - Isfahan, Iran , Atapour, M Department of Materials Engineering - Isfahan University of Technology - Isfahan, Iran , Ashiri, R Department of Materials Science and Engineering - Dezful Branch - Islamic Azad University, Iran , Ghassemali, E School of Engineering - Jo¨nko¨ping University, Jo¨nko¨ping, Sweden
Abstract :
In this study, the effects of the second pulse resistance spot welding on the microstructure and mechanical
properties of transformation induced plasticity 1100 steel were evaluated. The thermal process after welding
was designed to improve metallurgical properties with pulse currents of 6 kA, 9 kA, and 12 kA after initial
welding with 10 kA current. The effect of the second pulse on mechanical and microstructural properties was
investigated. The fracture of the welds was for pulsed samples of 6 kA and 9 kA pull out with mechanical test.
Due to the existence of the microstructure including the equiaxial dendritic and ner in fusin zone in the pulsed
current of 9 kA, the maximum fracture energy, and maximum force were observed. A signicant decrease in the
FZ hardness in 6 kA current was observed in the nano-hardness results, which was attributed to the existence of
martensitic and ferrite temper. The highest ratio of CTS/TSS was obtained for 6 kA and 9 kA, respectively, and
force-displacement evaluation was maximum in 9 kA. The fracture surfaces included dendrites and dimples. The
results of partial fracture revealed separation in the coherent boundaries of the coarse grain of the annealed
region.
Keywords :
Dendritic microstructure , Shear tensile , Fracture surface , Second pulse current , Resistance spot welding
Journal title :
Astroparticle Physics
