Effect of Cr-Ni coated Cu-Cr-Zr electrodes on the mechanical properties and failure modes of TRIP800 spot weldments


ERTEK EMRE H. , Bozkurt B.

ENGINEERING FAILURE ANALYSIS, cilt.110, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

Özet

Resistance spot welding (RSW) is a highly preferred welding process in the automotive and other industries because of its faster and economical processes and also it has higher quality. However, during the joining process, the temperature at the electrode tip reaches the highest value and, in the meantime, electrode tips are deformed. For this reason, the electrode wears down with increasing weld numbers, which changes the thermal, electrical, and mechanical contact conditions at the electrode and sheet interfaces. The coating is generally applied onto the surface of Cu-Cr-Zr electrodes for extended electrode life during RSW process. In this study, the tip surfaces of the electrodes were coated with Cr-Ni filler metal by using electro-spark deposition (ESD) coating method under 40, 80, and 120 V. Consequently, the effects of the coating on electrode characteristics and properties of the TRIP800 resistance spot weldment are investigated. The mechanical behaviors of the joined samples under static load were investigated by applying a tensile shear test and cross tension test. Tensile-shear strength, cross-tension strength was determined, and the failure modes of the samples was investigated. The nugget size was measured by stereo microscope. Microstructure investigations have also been carried out by optic microscope and scanning electron microscopy (SEM).