Prediction of Strength of Spot-Welded Joints by Measurements of Local Mechanical Properties

Tensile testing technique for the small sample was newly developed. Small tensile specimens with gage length of 1mm were taken from spot welds of high tensile strength steel sheets, and stress-strain relationships and ductility of base metal, heat affected zone including corona bond and nugget were individually measured. Finite element analyses of spot-welded joints under the conditions of static and dynamic tensile-shear loading were carried out with these local mechanical properties to predict the fracture mode and strength of the joints. It was clarified that the effects of both nugget diameter and class of steels were evaluated with good accuracy.