Charpy Impact Testing of the Newly Developed High Gamma Prime Ni-Based LW LCT Superalloy for Qualification of 3D AM of Components for Petroleum and Natural Gas, Turbine Engines, and Aerospace Industries

Abstract High gamma prime Ni-based superalloys have been used for decades in the manufacture of turbine blades, nozzle guide vanes (NGVs), combustors, and stator components that are exposed to high temperatures and stresses under operating conditions. The superior strength and creep properties of superalloys have been attributed to the high volume fraction of Ni3Al and Ni3Ti gamma prime (γ′) phase, which affects weldability. Successful welding and 3D AM of most commercially available Ni-based superalloys requires preheating above 900°C, which complicates the technology and increases manufacturing costs. To facilitate 3D AM of high-temperature components, the ambient temperature weldable LW LCT superalloy with 55 vol% γ′ phase was developed for 3D AM using laser powder bed fusion (LPBF) and direct energy deposition (DED) and for repair of turbine engine components by manual GTAW. All components produced by LPBF and DED and joined by GTAW welding for the oil and gas industry in accordance with API 20S and ASME B31T standards, respectively, should be subjected to Charpy impact testing in accordance with ASTM E23. However, the Charpy test has not been used to characterize superalloys due to the high service temperature of turbine engine components and the low ductility of high γ′ Ni-based superalloys at ambient temperature. Therefore, the current study was initiated to evaluate the applicability of Charpy impact testing for characterization and qualification of LW-LCT GTAW welds and LPBF material for 3D AM of various components for petroleum and natural gas, turbine engine, and aerospace applications. Charpy test results of Ni-based Haynes 230 annealed sheet, cast equiaxed GTD111 superalloy, and single crystal PWA1484 material are also provided for comparison.