Effect of picosecond laser surface texturing under Babbitt coating mask on friction and wear properties of GCr15 bearing steel surface

Abstract

The recast layer is usually formed during laser texturing of GCr15 bearing steel. The recoil pressure (caused by material vaporization) and Marangoni heat flow cause the molten material to splash out and accumulate at the texture edge to form the recast layer. The adverse thermal effects of laser texturing can cause hot cracks, non-uniform hardening zones, and MC carbide growth. These phenomena are generally unfavorable to the tribological properties of surfaces. This study proposes an effective solid mask laser ablation (SMLA) method for reducing the adverse thermal effects caused by laser texturing (such as recasting layer and splashing molten material). The results show that the shape of micro-dimples treated by SMLA was more regular. The accumulation of the recast layer and heat affected zone (HAZ) was also significantly reduced. The multi-layer samples textured by the SMLA method have better properties of storing oil and capturing the wear debris. The soft mask can also act as a solid lubricant. The coefficient of friction (COF) and specific wear rate of samples were significantly reduced.