Effect of Weld Root Gap on Tensile Shear Strength in Dual Phase Steel

In this study, the effect of weld root gap on tensile shear strength in dual phase steel which is one of popular Advanced High Strength Steels was investigated with base metal and overlap weld specimens by gas metal arc welding. The result of tensile strength test shown the reduction of tensile shear strength for overlap weld specimens compared to base metal specimen. And depends on the increasing weld root gap length between upper and lower sheet, the ultimate tensile shear, yield strength and strain rates were also decreased except to a case of 1.5 mm weld root gap specimen. The bending occurred by the offset between center of specimen and upper & lower sheet center line during testing until coincided all center lines of specimens, and then while necking on the heat affected zone the specimens were separated with ductile fracture mode. At final fracture area of middle of surface, the dimples and voids were inspected from all specimens.