Research On Microstructure And Properties Of Wear And Corrosion Resistant By Laser Cladding In Saturated Brine

The oil drill pipe is easy to be corroded and worn in the process of working in the saturated brine environment, which causes great economic losses. The conventional method is difficult to repair the failure parts. The laser cladding technology can be formed a metallurgical bonding layer with substrate on the surface of the workpiece, which can improve the performance of materials in the aspects of oxidation resistance, high temperature resistance, wear resistance and corrosion resistance. Based on two aspects of the powder system and laser parameters, a Co based /Al2O3/(La2O3) composite laser cladding powder was designed in this paper?Experiment on the flexible machining system using 10 CO2 KW laser cladding. By means of OM, SEM, EDS, XRD, hardness tester, friction wear tester, electrochemical workstation, the micro area composition, phase composition, microhardness, wear resistance and corrosion-resistance were investigated. The experimental procedure is as follows: Firstly, 12 groups of powder formulations were designed, and the microhardness of the coating was tested by laser cladding, and the optimum laser cladding powder formulation was determined. Secondly, the optimum laser cladding parameters were determined by orthogonal experimental design: laser power was 3kW, scanning rate was 6mm /s, spot diameter was 4mm, lap ratio was 40%; In the end, the phase composition and microstructure of the coating were studied. The results show that the microstructure of the coating is mainly composed of the primary phase and the eutectic structure. Under the condition of fixed Al2O3 content, with the addition of La2O3, the microstructure is uniform and the grain size becomes smaller. Continue to increase the content of rare earth La2O3,phase increased in the cladding coating. Co and Al in the weld pool formed compound Al13Co4, Co, Si and C in Cr-based alloy powder were decomposed into the bath and formed compound Cr9.1Si0.9, SiC. When the amount of La2O3 was 0.4 wt.%, the hardness of the coating was the highest, which was 627.23HV1. The best wear resistance, stable friction coefficient of 0.43; Lost weight is the lowest 0.005g; The cladding coating wear surface is narrow, shallow furrow. And rare earth La2O3 addition can significantly improve the substrate resistance corrosion resistance. The corrosion resistance of the laser cladding coating is the best when the amount of La2O3 is 0.2 wt.%, the self corrosion potential Ecorr and the self etching current density icorr are-233.418 mV, 1.041 A/cm2.