摘要
M50 steel,commonly utilized in aircraft engine bearings,is susceptible to friction-induced failures,particularly in high-temperature service conditions.To address this issue,various strategies have been proposed,with laser shock peening(LSP)garnering significant attention due to its deeper residual stress penetration and excellent surface integrity,whereas the underlying strengthening mechanisms have not yet been fully elucidated.In this study,we systematically investigate the impact of LSP treatment on the tribological properties of M50 steel at temperatures of 25 and 300℃,alongside elucidating the relevant micro-mechanisms.Microstructural analysis reveals that laser impact strengthening primarily arises from dislocation proliferation,resulting in a surface hardness increase of approximately 14%and the formation of a substantial compressive stress layer reaching a maximum value of about 1200 MPa,with a depth of around 2 mm.Friction test results demonstrate reduced coefficients of friction and wear rates following LSP treatment at both temperatures.Notably,a more pronounced reduction is observed at 300℃,with values decreasing by 41.4%and 55.8%,respectively.The enhanced performance is attributed to the synergistic interplay of compressive residual stresses,work-hardening layers,increased density of dislocations,and substantial microstructure refinement.
基金
supported by the National Science and Technology Major Project of China(No.2017-VII-0003-0096)
the National Natural Science Foundation of China(Grant Nos.52205240 and 52201140)
the Young Elite Scientist Sponsorship Program by CAST(Grant No.YESS20200321)
the Natural Science Foundation for Youths of Shaanxi Province(No.2023-JC-QN-0521)
the China Postdoctoral Science Foundation(Grant No.2022M723874).
