Comparative Study on Microstructural Characteristics and Fatigue Performance of 10 mm Thick 5083-H111 Aluminum Alloy Plates Processed by Different Cutting Methods

This study evaluates the applicability of laser cutting to 10 mm thick 5083-H111 aluminum alloy plates by comparing fiber laser cutting, waterjet cutting, and mechanical grinding. The cut-edge morphology, microstructure, tensile properties, and fatigue behavior were systematically investigated, with particular emphasis on the effects of laser-induced thermal input on the heat-affected zone (HAZ), grain orientation, precipitates, and residual stress. A fatigue risk factor (Rf) was further introduced to quantify fatigue cracking susceptibility. At 1 × 107 cycles, the fatigue strengths of the mechanically ground specimen and the waterjet-cut, laser-cut without dross removal, and laser-cut with dross removal specimens were 119.18, 99.21, 60.19, and 67.64 MPa, respectively. Dross removal increased the fatigue strength of the laser-cut specimens by 12.38% by reducing local stress concentration, although their fatigue performance remained inferior to that of the other two processes. Periodic surface striations and heat-affected-zone degradation were identified as the primary causes of fatigue strength reduction. Fatigue cracks mainly initiated at dross roots, surface striations, and nearby defects in the laser-cut specimens. The laser-cut specimens exhibited the highest fatigue risk factor (Rf = 1.32), compared with 0.36 for waterjet cutting and 0.16 for mechanical grinding, corresponding to the lowest fatigue life.