Turbine Blade Tip Repair by Laser Directed Energy Deposition Additive Manufacturing Using a Rene 142–MERL 72 Powder Blend

Abstract

Laser directed energy deposition (LDED) was used with a powder blend comprising 75 wt.% Rene 142 and 25 wt.% of Merl 72 (4275M72) for turbine blade tip repair applications. Sound samples could be deposited at ambient temperature on Haynes 230. The microstructural analyses showed the presence of fine gamma prime precipitates in the as-deposited samples, while after aging, the alloy possessed around 40 vol.% with a bimodal precipitate size distribution. Also, the alloy contained Ta-Hf-W carbides in different sizes and shapes. Tensile testing from room temperature up to 1366 K was performed. The 4275M72 deposits possessed higher tensile properties compared to Rene 80 in this temperature range but lower elongations at the elevated temperatures. The creep properties of 4275M72 samples at 1255 K were superior to Rene 80. Also, the oxidation resistance of deposited 4275M72 was similar to Rene 142. The combination of high mechanical properties, creep behavior, and oxidation resistance of LDEDed 4275M72 makes it a suitable alloy for tip repair of turbine blades.