Effect of Strain Rate on Tensile Behavior of Q460 Steel and Submerged Arc Weld Joint

Q460 steel was welded by submerged arc welding technology, the effect of strain rate (0.001-100 s^-1) on tensile properties and fracture morphology of base material and weld joint was studied. The results show that the room temperature quasi-static (strain rate was 0.001 s^-1) yield strength and tensile strength of the weld joint were close to those of the base material, but the percentage elongation after fracture decreased obviously. The yield strength and tensile strength of the base material increased with the increase of the strain rate, and was sensitive to strain rate. When the strain rate was 0.01-0.1 s^-1, the yield strength and tensile strength of the weld joint were equivalent to the quasi-static strength. When the strain rate was 1-100 s^-1, the strength increased obviously, that is, the strength was sensitive to high strain rate. The percentage elongation after fracture of the base material and the weld joint decreased first and then increased, and the minimum values appeared at the strain rate of 0.01, 0.1 s^-1, respectively; the rate of increase of the weld joint was small. The increase of strain rate made the dimples in tensile fracture of the weld joint became smaller and shallower first and then larger and deeper, but did not change the micro-fracture mechanism. The joint fractured in ductile mode.