Numerical Simulation For Silicon Carbide/Stainless Steel Composite Coatings In Laser Surface Alloying On AZ31B Magnesium Alloy

Laser surface alloying as a new type of surface modification technology, can obviouslyimprove the wear resistance, corrosion resistance and corrosive wear resistance and otherproperties of cheap base material, which makes it get a wide range of applications. I did thenumerical simulation to get rule and characteristics of silicon carbide/stainless steel mixedpowder laser alloying temperature and stress in this paper, and then checked the simulationresults by experiment.By using the ANSYS software, a finite element model which simulates a real LSA process of amulti-component SiC-316L metal powder system was established to calculate the3D transient temperaturefield. I considered comprehensively the effect thermal conduction，thermal convection，thermal radiationPhase-change latent heat. APDL language is used to promote the movement of laser. The simulationresults show that the shape of temperature field distribution is oval. The maximum depth for alloyingpool is not the bottom of center spot, but slightly lag. In the scanning process of multi-tracks laser alloying,the temperature is gradually increasing finally become stable for the first scanning track and thetemperature for the second scanning track increases at the beginning and then decreases. When scanningspeed is small enough, quantity of heat can be obvious to conduct to thin-walled side. Temperature ofinterface node over time in alloying scanning process will constantly present fluctuation of peak, and thengradually become flat.Based on the results of temperature field, a finite element model for analyzing the stress field wasestablished by using an indirect thermal-mechanical coupling method. The thermal stress in Z direction ofthe surface is given priority to compressive stress and it is given priority to tensile stress for the interface.The crack generally forms at the interface because of stress concentration. As the tensile stress in Xdirection is greater than that of Y direction, most of cracks are perpendicular to the scanning direction. Thethermal stress in all direction is directly proportional to laser power and inversely proportionalto scanning speed.The optimal process parameters are that the laser power is2200W and scanning speed is1200mm/min,which are consistent with the simulation results. Compare to substrate, the wear resistance andhardness are raised by1time and2times by the optimal process parameters.