Synergistic effect of laser surface texturing and laser discrete quenching on improving tribological properties of M50 steel under starved lubrication condition

To mitigate the coupled lubrication-wear failure of M50 steel under starved lubrication conditions, this study proposes a composite surface treatment process that integrates laser surface texturing (LST) and laser discrete quenching (LDQ), referred to as LST + LDQ. In order to evaluate the effectiveness of LST + LDQ on the tribological properties of M50 steel, untreated, LST-treated, and LDQ-treated samples were used as reference specimens in unidirectional sliding friction tests conducted with a reciprocating ball-on-disk tribometer. Experimental results demonstrate that the LST + LDQ treatment significantly increases both surface microhardness and compressive residual stress relative to the LDQ-treated sample. Consequently, the LST + LDQ treated sample exhibits a significantly lower average friction coefficient and wear mass than the untreated sample—primarily attributable to the synergistic strengthening mechanism between LST and LDQ. LDQ simultaneously increases surface microhardness and elevates residual compressive stress in the surface layer: the former suppresses plastic yielding within the contact zone, while the latter promotes microcrack closure and impedes dislocation motion—thereby significantly enhancing surface wear resistance. The LST + LDQ treated surfaces significantly extend the functional service life of the micro-dimples, providing continuous lubricant reservoirs for the contract areas and effectively entrapping wear debris. Consequently, the synergistic interaction between LST and LDQ significantly improves tribological performance under starved lubrication conditions.