Modification of surface treatment on the strength of 30CrMnSiA steel adhesively bonded joints

30CrMnSiA steel substrate was treated with sandblasting and laser texturing to improve its adhesive-bonded strength. The characterization of treated substrate was performed by surface morphology, surface roughness (Ra and Rz) and wettability. The water contact angle (WCA) was measured and solid surface energy was calculated. The adhesive-bonded single lap joints were then prepared and tested. For comparison, the similar discussion was established for the metal substrate with degreasing. Fracture surface was observed and analyzed by SEM and EDS. The results indicated that the surface roughness was increased both with sandblasting and laser texturing. The wettability was improved due to the decrease of WCA and the increase of surface energy. The tensile shear strength of adhesive-bonded joints after sandblasting and laser texturing increased by 151% and 465.9% respectively. The proportion of adhesive on the same side (left side) of joints was 1.5%, 29.3% and 67.7% under three types of joints. The fracture mode of specimens with degreased and sandblasted substrate was found to be an interfacial fracture, while it was mixed fracture with laser textured substrate.