A laser powder bed fusion–based methodology for repairing damaged nickel-based turbine blades: Investigation of interfacial characteristics and hot isostatic pressing treatment

Abstract

This study presents a methodology for repairing a damaged nickel-based turbine blade via laser powder bed fusion (LPBF) additive manufacturing. Specifically, the CM247LC nickel-based alloy was utilized to repair a damaged SRR99 nickel-based blade with LPBF, followed by hot isostatic pressing (HIP) post-treatment. The LPBF repair process achieved crack-free metallurgical bonding at the CM247LC/SRR99 interface with large epitaxially grown grains. Furthermore, HIP facilitated the formation of γ/γ’ phases with comparable dimensions at the interface as well as in the CM247LC and SRR99 regions through recrystallization. Additionally, the columnar grains in the LPBF-printed CM247LC region transformed into coarse equiaxed grains after HIP, accompanied by precipitation of nanoscale Hf-rich carbides. Meanwhile, microcracks in the LPBF-printed CM247LC region and shrinkage pores in the cast SRR99 region were effectively eliminated. The LPBF-printed CM247LC exhibited an 8.62% higher hardness compared to that of SRR99. The repaired samples showed an ultimate tensile strength of 791 MPa, with fracture occurring at the SRR99 side, indicating a reasonable metallurgical bonding strength at the CM247LC/SRR99 interface. The findings offer a novel alternative for the industrial application of repairing damaged nickel-based turbine blades.