Laser deposition is a promising and cost-effective repair and rejuvenation processes for Directional solidified (DS) superalloy blades. This paper focuses on the investigation on mechanical performance of the as-deposited directionally solidified IN 738 structure.
Continuous DS columnar structure is available in multi-layer overlap deposition via laser deposition parameter optimization. Heat treatment has no obvious influence on the directional solidification characteristic. Large amount of γ′ particles with size of 100 to 200nm precipitate during heat treatment. Heat treatment decreases the average hardness of the deposition layers from HV0.2397 to HV0.2361. The yield strengths of the deposition layers at room temperature show isotropy in different directions. The ductility is better along directional solidification direction. After heat treatment, the yield strength of the deposition layers decreases about 110MPa. Compared with the DS substrate, the yield strength of the deposition layers is lower but ductility is better. The tensile strength of the deposition layers at 900°C is about 670MPa, similar to the DS substrate. It will decrease about 130Mpa after heat treatment and it is isotropy in different directions. All the fractures in the deposition layers consist of ductile nests which are initiated by carbide
The results indicate the mechanical performance of the deposition layers by laser can meet the need of practical use.