Quantitative research on microstructure and thermal physical mechanism in laser melting deposition for Invar alloy

Considering the laser power, scanning speed and powder feeding rate, the experimental investigation of the laser melting deposition (LMD) with coaxial powder feeding for Fe-36Ni Invar alloy was presented in this paper. The influence of different parameters on morphology of deposition layer (DL) was analyzed in detail. Besides, the microstructure in HAZ of LMD for Fe-36Ni Invar alloy and the width of HAZ were quantitatively studied. Meanwhile, a three-dimensional finite element (FE) model considering the effect of laser power and scanning speed on heat transfer process was established to investigate the thermal field of LMD process for Fe-36Ni Invar alloy. In addition, the linear heat input was introduced into this paper to analyze the comprehensive influence of process parameters on the thermal field during LMD process. Moreover, combining the simulation results of thermal field, the thermal physical mechanism of the microstructure formation in HAZ was discussed.