Solidification cracking sensibility of narrow gap laser welding on ITER-grade austenitic stainless steel

This study aimed to investigate the solidification cracking in narrow gap laser welding (NGLW) of ITER grade austenitic stainless steel 316LN. The results show that NGLW of ITER grade 316LN presents high solidification cracking sensitivity. The cracking always occurred in the centerline of build-up weld with a certain depth, not in root and cosmetic layers. The crack mostly propagates on the surface of the weld and it could be be healed by the following layer welding. The healing efficiency depends on the overlapping zone between the two layers. Other various laser welding processes such as autogenous laser welding (ALW), double-sided NGLW, and narrow gap pulsed laser welding (NGPLW) were studied. These welding processes present better cracking resistance than that of NGLW because of the stress distribution, microstructural characteristic and constraint condition of welded joints.

Automated summary

The study revealed high solidification cracking sensitivity in NGLW of ITER grade 316LN, with cracks mostly occurring in the centerline of build-up weld and being able to be healed by subsequent layer welding. Other laser welding processes like ALW, double-sided NGLW, and NGPLW showed better cracking resistance due to various factors such as stress distribution and microstructural characteristics.