Effects of Strain and Contents of Impurity Elements on Center-line Crack Susceptibility in Laser Beam Welds of Type 316L Stainless Steel

Abstract

To make clear the effect of strain occurred in weld metal of Type 316L stainless steel during laser beam welding (LBW) on center-line cracking in LBWs, side-bead test was adopted to evaluate the susceptibility by measurement of the crack length. The stainless steels varied with impurity elements such as P and S were used as the materials for the test. From the side-bead test, the crack length decrease with increase in the laser welding velocity. Compared with high and low amounts of impurity elements, the crack length occurred in welds metals with higher contents of impurity elements were remarkably longer than those in lower ones. To discuss the phenomena, the thermal-elastic-plastic FEM analysis considering with temperature dependent interface element has been conducted to simulate the side-bead test. From the calculation, the cracking behavior recognized in the actual side-bead test was relatively in accordance with calculation. On the basis of these results, the side-bead test was a useful test method to evaluate the crack susceptibility. In addition, it seems to be suggested that the susceptibility may be possible to predict by the FEM analysis due to use correct physical constants of the materials.