Improved wear resistance of directed energy deposited Fe-Ni-Cr alloy via closed-loop controlling laser power

Abstract

Wear resistance influences the service life of critical components and limits the widespread application, and the thermal accumulation is a key factor affecting wear property in the coating preparation. In this work, the effects of thermal accumulation and suppression of the melt pool on wear performance were compared. We proposed a closed-loop control method based on proportion integration differentiation (PID) algorithm to improve the wear resistance by adjusting the laser power and controlling the melt pool size (MPS) in real time. The results demonstrated that the cross-growth of large-sized dendrites in the traditional mode resulted in poor wear performance. In contrast, dense equiaxial crystals without preferential orientation were formed in the closed-loop control mode, which caused the formation of a dense and homogenized coating. The grain refinement strengthening and increased microhardness led to the significant reduction of the wear rate to ~3.0·10−6 mm3/Nm, which was an-order-of magnitude lower than that in the traditional mode.