Effect of Probe Indentation Depth on Mechanical Behavior of Friction Stir Spot Weld of Al 6061-T6

In the present study, an experimental study on the friction stir spot welding of Al 6061-T6 alloy was carried out to investigate the effect of indentation depth of welding probe. The depth of indentation was determined to be 2.75, 3 and 3.5 mm. According to the static results, increasing the indentation depth has improved the static strength, significantly. Therefore, the depth of indentation of 3.5 mm has the optimum static performance. Based on the fatigue results, at high load levels, the indentation depth of 3.5 mm was more appropriate. However, at the lower load levels, the fatigue behavior of 3 mm indentation was better than the other welding conditions. In fatigue specimens, two failure modes of the shear fracture and the transverse crack growth in the sheet were observed. However, in the 2.75mm condition, only the shear fracture was occurred. In the 3.5mm condition, transverse crack growth was observed at the most load levels. In the 3mm condition, at high load levels, the shear fracture and at the low load levels, transverse crack growth took place.

Keywords:

Friction stir spot welding , Fatigue , Mechanical behavior , Depth of indentation.