Tribology performance of laser-peened MB8 magnesium alloy under different working conditions

Due to low hardness of magnesium alloy, surface wearing often causes fatigue fracture of magnesium alloy component, which seriously affects flight safety of aircraft. Laser shock peening (LSP) is a new surface plasticity strengthening technology, which can increase the hardness and strength of metal materials by work hardening, thereby significantly improving friction and wear performance. In this work, MB8 magnesium alloy samples were treated by LSP with a group of optimized parameters. The laser-peened samples were tested on friction-wear testing machine under different loads of 50 gf, 100 gf, 150 gf, and 200 gf; rotate speeds of 100 r/min, 200 r/min, 300 r/min, and 400 r/min; and friction pairs of Si3N4 ball and 416L ball. Microhardness, abrasion morphology, and elemental contents were measured by a microhardness tester, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS), respectively. The experimental results show that LSP could effectively enhance the anti-wear performance of the magnesium alloys, but the amplitude for the enhancement depends on the working conditions. To be more specific, LSP has a better effect on anti-wear property under low load, low rotate speed, and ceramic friction pair conditions. Moreover, the underlying anti-wear mechanisms of the LSPed samples under different working conditions were revealed.