Fatigue Strength of Spot Welds in Titanium-Bearing HSLA Steels

The effects of base metal yield strength, thickness, weld diameter and load ratio on the fatigue strength of spot welds in titanium-bearing HSLA steel have been examined for specimens tested with both tensile shear and cross-tension loading. Weld strength, as measured by the load range, was found to be essentially independent of base metal strength but increased in a complex manner with increasing material thickness or weld diameter and decreased with an increasingly positive load ratio. Equations were developed for estimating fatigue life from material thickness, weld diameter, load range and load ratio. For lives of 5 × 10³ to 5 × 10⁶ cycles, a good agreement was obtained between estimated and measured values for both tensile shear and cross-tension loading.