High temperature performance of laser deposition GH105 layers on nickel base super alloy blade

Abstract

Laser deposition is considered a promising rejuvenation approach for nickel base super alloy blades for various kinds of erosion, abrasion or cracking resulted from high temperature, high pressure and complicated vibration environments. The induced residual stress/its impact on the fatigue property and the high temperature performance are two main research issues for successful rejuvenation of blades. We have previously reported our research on residual stress measurement, using laser shock peening, electronic shock peening and magnetic process to change the residual tensile stress into a compress stress and such significantly improves the fatigue properties.This paper focuses on the high temperature performance of laser deposition GH105 layers. Laser deposition of a nickel base super alloy (GH105) powder was performed via a powder feeding technique on nickel base supper alloy blade by a high power CO2 laser. The research indicates that the cladding layers of GH105 under optimized processing parameters have dense microstructure, ultra-fine grains, good surface quality and good metallurgical bond with the substrate. The microstructure consists of γ-Ni matrix, a few carbide precipitates and γ’-phase. The micro-hardness of the cladding layer reaches HV0.2 422, while the blade substrate is HV0.2 343. The elevated temperature tensile strength of the cladding layer at 850℃ is 530MPa, higher than that of the cold-drawn rod, which exceedes the requirement of the blade substrate. The ball-on-flat wear test at 500℃ indicates that the relative abrasive wear property of the laser deposited layer is better than that of the substrate. As the result, the GH105 laser deposition layer meets the high temperature performance requirements for blade rejuvenation.Laser deposition is considered a promising rejuvenation approach for nickel base super alloy blades for various kinds of erosion, abrasion or cracking resulted from high temperature, high pressure and complicated vibration environments. The induced residual stress/its impact on the fatigue property and the high temperature performance are two main research issues for successful rejuvenation of blades. We have previously reported our research on residual stress measurement, using laser shock peening, electronic shock peening and magnetic process to change the residual tensile stress into a compress stress and such significantly improves the fatigue properties.This paper focuses on the high temperature performance of laser deposition GH105 layers. Laser deposition of a nickel base super alloy (GH105) powder was performed via a powder feeding technique on nickel base supper alloy blade by a high power CO2 laser. The research indicates that the cladding layers of GH105 under optimized processing parameters ha...