Friction stir spot welding of cold-rolled low carbon steel plates using TiC0.5N0.5–Xwt%W (X=70, 72, 75) cermet tool specimens

Abstract

Friction stir spot welding (FSSW) tests of steel plate cold commercial (SPCC) cold-rolled low-carbon steel plates with a thickness of 1 mm were conducted using TiC0.5N0.5–X wt% W (X = 70, 72, 75) cermet tool specimens with Ti(C, N) core–(Ti, W)(C, N) rim structures and the W–based alloy phase. All of the TiC0.5N0.5–X wt% W cermet tool specimens were prepared by the spark plasma sintering of blended TiC0.5N0.5 and W submicron powders. The SPCC steel plates could be welded more than 2000 times using a TiC0.5N0.5–72 wt% W cermet tool specimen, whereas it has been reported that the steel plates could be welded approximately 1000 times using a commercially available Si3N4 tool specimen. Both the upper and lower steel plates after the 6th, 1006th, 1506th, and 2006th welding using the TiC0.5N0.5–72 wt% W cermet tool specimen were joined together without any voids or cracks. The SPCC steel plate specimens after the 1003rd, 1503rd, and 2003rd welding using the TiC0.5N0.5–72 wt% W tool specimen were considerably bent near the joint during the tensile shear test, indicating that the bonding strengths of the plate specimens were at least as high as the yield stress of the untreated SPCC steel plates.

Keywords

• Friction stir spot welding
• Ti(C
• N)–W cermet
• SPCC steel plate
• Spark plasma sintering