Investigation of the microstructure and impact toughness of high-intensity fiber laser welded AISI 904L super austenitic stainless steel joints

Abstract The present investigation describes the joining of AISI 904L similar joints using a fiber laser welding approach for application in the power industry. The 5 mm-thick sheets were joined, and metallurgical and mechanical characteristics were conducted on the joints to ensure the structure-property relationship at room temperature. The metallurgical investigation involved field emission scanning electron microscopy and electron backscattered diffraction analysis to ensure the Mo-rich segregation in the interdendritic arms, along with precipitation of M 23 C 6 carbides. The lower heat input and rapid rate of cooling reveal the nucleation of columnar and cellular dendrites, accompanied by strain deformation. The tensile fracture occurred in the weld zone, showing a higher strength of 639 ± 4 MPa with a yield strength of 320 ± 2 MPa and 37 ± 2% of elongation. Toughness studies showed that the joints exhibited a toughness of 107 ± 5 J, notably higher than that of BM.