Numerical simulation of convex shape beam spot on stress field of plasma-sprayed MCrAlY coating during laser cladding process

To reduce the thermal stress at the clad layer and further reduce the crack generation in the laser cladding process, a method of controlling the cracks at the clad layer by changing the laser energy density is proposed. Comparative thermal–mechanical coupling finite element analysis was performed on the uniform rectangular and convex shape beam spot cladding processes on plasma-sprayed MCrAlY coating through the numerical simulation method based on the ANSYS software. Results show that rapid heating and cooling characteristics, which are typical in laser processing, are manifested in the cladding process using a uniform rectangular spot, whereas a convex shape spot can exert preheating and slow cooling effects to a certain extent, thereby reducing the temperature gradient of the cladding and non-cladding zones. In addition, on the precondition of equivalent cladding effect, the thermal stress at the clad layer is also low, enabling the effective mitigation of the cracking tendency of the clad layer. 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 obtaining a convex shape spot.