Numerical simulation and mechanical property of 1Cr15Ni4Mo3N stainless steel efficiently repaired by laser metal deposition with a synergistic improvement strategy

Laser metal deposition (LMD) optimized with the strategy of synergistic improvement of the laser power (P) and powder feed rate (PFR) was employed to repair 1Cr15Ni4Mo3N stainless steel. Herein, the P of the 1080 nm fiber laser was increased layer by layer (1000, 1200 and 1300 W) while raising the PFR (8.5, 10, 11.5 g/min), with the aim of achieving favorable performance and higher efficiency. Additionally, the thermal behavior during repair process was exposed by finite element analysis, and the comprehensive analysis of the temperature distribution and the thermal cycle are in good agreement with the trend of the microhardness variation in the deposition area. The growth rates of the molten pool depth at the centers of the second and third layers are 19.79 % and 12.33 %, respectively, indicating that the poor fusibility of the interlayer fusion zones caused by the increased PFR has been avoided due to the improved P. Moreover, the average tensile strength and the impact toughness of the laser-repaired specimen (LS) are derived to be 1489 MPa and 88.7 J/cm2, which are 10.12 % and 10.60 % higher than that of the base material (BM), respectively, and the elongation of the LS reaches 17.3 %. The mechanical properties of the LS are guaranteed while the efficiency is improved, suggesting that the strategy and the developed finite element model can serve to provide application value in the rapid maintenance of precipitation- hardening stainless steel.