Effect of Microstructures and Defects on Dynamic Compression and Shear Performance of Laser Metal-Deposited GH4169 Superalloy

This work evaluated the effect of the unique microstructures and defects on the dynamic mechanical behavior of laser metal-deposited (LMD) GH4169. The compression and shear properties were tested at strain rates ranging from 0.001 to similar to 30,000/s. The difference in dynamic properties between the LMD and forged GH4169 was estimated by a comparative study of their dynamic compressive response at different temperatures. The initial microstructures and fractured characteristics were observed using a scanning electron microscope. The results showed that both the compressive and shear strength exhibit significant strain-rate sensitivity. The microstructural anisotropy leads to different compressive strengths depending on loading direction. However, the anisotropy of shear properties is not obvious, resulting from the narrow deformation area of shear specimen. Owing to the coarse columnar grains in the LMD GH4169 sample, the compressive strength of the LMD sample was lower than that of the forged sample. The crack and fractography morphology showed that Laves phases and defects in the LMD samples could be sensitive points for deformation and fracture under dynamic loading.