Research of the effects of laser power variation on the properties of laser cladding Ni45/Cr3C2/MoS2 self-lubricating wear-resistant coatings on the surface of 300M ultra-high-strength steel

To enhance the wear resistance of 300M ultra-high-strength steel, a Ni45/Cr3C2/nickel-packed MoS2 composite coating is fabricated using laser cladding technology. The impact of varying laser power on coating properties is investigated. Results show that MoS2 partially decomposes during laser cladding, forming new sulfide lubricating phases, CrxSy, and NiS, while Cr3C2 partially decomposes to create new reinforcing phases, Cr23C6, and Cr7C3. Reinforcing phase and lubricating phases are mainly distributed in the surface of 1100W coating. The surface hardness of the 1100W coating reaches 509 HV0.5, with an average hardness of 508.65 HV0.5, both surpassing those of the 800W coating (surface hardness of 477 HV0.5 and average hardness of 502.88 HV0.5). Wear rates for the 1100W and 800W coatings are 0.29 and 0.21 times that of the 300M steel substrate. Primary wear mechanisms for the 300M steel substrate include severe adhesive wear, abrasive wear, and oxidative wear; for the 1100W coating and 800W coating, predominant mechanisms are abrasive wear and oxidative wear. With frictional wear progression, peeling of lubricating phases and hard particles leads to increased friction coefficients of 1100W coating. Conversely, due to its superior toughness, the 800W coating displays a more stable friction coefficient and lower wear rate.