Effect of Heat Treatment on the Microstructure and Properties of K4169 Repaired by Laser Deposition

To address the defects and damage to high-temperature K4169 alloy components during casting and processing, as well as during service, laser deposition repair of K4169 alloy was carried out and the effect of heat treatment on the microstructure and properties of the repaired samples was investigated. After aging heat treatment, a large number of γ' phases and a small number of γ'' phases precipitated in both the repair zone and the substrate zone, but the δ phase was still observed only in the substrate, the number did not change significantly, the strength of the repaired sample improved, and the plasticity decreased. After solution + aging heat treatment, more γ'' phases precipitated from the sample, which led to a further increase in strength. The precipitation of the δ phase was observed in the repair zone, the number and distribution scope of δ phases in the substrate zone increased. In addition, the plasticity was greater than that of the aged sample because of the dissolution of the brittle Laves phase and the cutting effect of the δ phase.