Effect of laser texturing on the surface characteristics and bonding property of 30CrMnSiA steel adhesive joints

Abstract The influence of laser texturing on the bonding property of 30CrMnSiA steel joints were investigated. Three patterns including dimple, groove and grid were laser textured on the 30CrMnSiA steel substrate by nanosecond fiber laser. The processed surface was characterized by surface morphology, surface roughness (Ra and Rz) and wettability. The single lap adhesive joints were fabricated and fracture surfaces were observed. The accelerated hygrothermal aging experiments were performed. The results indicated that surface roughness and wettability were both enhanced after laser texturing. The grid patterned substrate was improved pronouncedly, where Ra increased by 400% and Rz was 13 times higher than as-received specimens, and the contact angle was decreased from 65° to 24°. The shear strength of adhesive joints for dimple pattern was not improved evidently, while it was 14.6 MPa and 23.3 MPa in the groove and grid patterned specimens, which was increased by 219%, 348% compared to as-received ones, respectively. The coverage of adhesive layer on the fracture surface was increased and the fracture mode of dimple and groove patterned specimens was adhesive failure and a cohesive failure was achieved for those joints with grid pattern. The bonding property was decreased after hygrothermal aging, and the residual strength of specimens with grid pattern was the highest. The fracture mode was not changed in all adhesive joints.