Effects of UIT on Microstructure and Properties of 441 Ferritic Stainless Steel Laser Welded Joint

Abstract

Abstract Effects of UIT (Ultrasonic impact treatment) on the microstructure and properties of laser welded 1.5mm 441 ferritic stainless steel sheets were studied. Results indicate that the surface of the butt joint generated an ultrasonically induced strengthening layer after UIT. The average microhardness of the layer was increased by 18.1%. The tensile strength of the specimens was increased. Moreover, UIT can decrease the residual stress of welded specimens, the maximum longitudinal tensile stress in the central area was decreased by 78.4%, and the transverse residual stress was converted into compressive stress. The cupping value was increased from 34.5 mm to 37.0 mm following UIT. In addition, the fracture position was changed from the central weld to the edge weld of the cupping hemisphere. The mechanical properties were increased due to the generation of strengthening layers and the decrease of residual stress by UIT.