This study investigates the effects of preapplied mechanical bending on microstructural evolution and defect formation during subsequent metal inert gas (MIG) welding of 304L stainless steel clad onto Q345R low‐alloy steel using a 316L filler. A set of references, bent‐only, welded‐only, and bent‐plus‐welded specimens, is examined by optical microscopy, scanning electron microscopy, and electron backscatter diffraction. In the bent‐only condition, 304L exhibits deformation twinning and strain localization, whereas Q345R shows elongated ferritic grains and gradual orientation gradients. Microhardness ranges from approximately 200 HV 0.5 in Q345R to 250 HV 0.5 in 304L, with local peaks of 275 HV 0.5 at the interface. Tensile tests indicate yield stresses of about 580–588 MPa in 304L and 450 MPa in Q345R, while toughness values range from 148 to 226 J depending on orientation and cladding thickness. Welding produces columnar solidification in the fusion zone, recrystallized austenite on the stainless face, and a narrow martensitic band in the heat‐affected zone (HAZ) of Q345R. The combined bend‐weld sequence intensifies interfacial heterogeneity, with increased misorientation, geometrically necessary dislocation clustering, and enhanced defect susceptibility near the trimaterial junction. Findings indicate that prior bending conditions the weld thermal cycle and promotes strain‐assisted microstructural pathways and defect initiation near the interface.
Fahem et al. (Sun,) studied this question.