感应加热对激光增材修复高温合金DZ125L组织 和力学性能的影响

By studying the microstructure and microhardness of the laser additive repair of directionally solidified superalloy DZ125L under an induction heating condition, the effect of induction heating on the formation mechanism of microstructure and the evolution of mechanical properties near the interface between repair layers and substrate is revealed. The results show that induction heating at 1 000 ℃ can effectively reduce the temperature gradient in comparison with the sample without induction heating. As a result, in repair layers, the primary dendrite arm spacing increases from 3.8 μm to 7.2 μm, γ' particles grow from 19.8 nm to 74.0 nm, and the heat affected zone(HAZ) extends from 200 μm to 500 μm. The microhardness continuously increases in the HAZ and reaches a plateau in the repair layers. The increased microhardness in the HAZ is mainly attributed to the volume fraction change of primary and secondary γ' precipitates, whereas the hardening mechanism in the repair layers is related to the γ'-size-dependent strengthening effect.