Vibration parameters optimum of 316L steel laser welding under high frequency micro-vibration condition

Abstract

High frequency micro vibration combined with laser was applied in the test. Effect of vibration parameters on the mechanical and micro-structure of High Frequency Micro-vibration laser welded 316L steel were investigated. The best laser welding process parameters were chosen by comparison of weld geometry. In detail, laser power (P) is 2.5 kW, welding speed (V) is 1.2 m min−1, defocusing amount (DA) is −5 mm. Three parameters including frequency (F), vibration acceleration (A) and angle (θ) were changed according to the orthogonal test scheme. The microstructure and the tensile properties of the welded joint were compared and analyzed. The morphology of weld tail was analyzed to describe hole stability. It was found that micro-structure and mechanical of joint was significantly influenced by A and F. In the case of vibration resonance, the higher the F, the better the ultimate tensile strength (UTS), and the higher the hardness. When F was 1360 Hz, UTS was 602 MPa. When A was increased from 10 to 60 m s−2, the UTS was improved by 10 MPa. HW and HL were even disappeared in a higher resonance state. Response surface analysis results showed that factors of F and A have significant effects on the width of weld. Width was increased by 3 mm. The effect of θ on width was little. It was obtained that optimum process parameters were F = 1360 Hz, A = 60 m s−2 and θ = 90°. UTS was 602 MPa, hardness was 214.5 Hv, and elongation was 40%. This is mainly due to the grain refinement strengthening.