Numerical Simulation of Convex Shape Beam Spot on Stress Field of Plasma-sprayed MCrAlY Coating During Laser Cladding Process

Abstract

In order to reduce the thermal stress at clad layer and further reduce the crack generation in the laser cladding process, a method of controlling the cracks at clad layer by changing the laser energy density was proposed. The comparative thermal-mechanical coupling finite element analysis was conducted for the uniform rectangular spot and convex shape beam spot cladding processes on plasma-sprayed MCrAlY coating through the numerical simulation method based on the ANSYS software. The results show that the rapid heating and cooling characteristics, which are typical in laser processing, are manifested in the cladding process using the uniform rectangular spot, and the convex shape spot can exert the preheating and slow cooling effects to a certain extent, so as to reduce the temperature gradient of the cladding zone and non-cladding zone. In addition, on the precondition of equivalent cladding effect, the thermal stress at the clad layer is also low, so the cracking tendency of the clad layer can be effectively mitigated. Relative to the laser beam shaped diffractive optical element special for design and manufacturing, superposing two uniform rectangular spots with different sizes and energy densities is a simpler and more effective method of acquiring the convex shape spot.