Effect of heat treatment on microstructure and mechanical properties of laser melting deposited Ni-base superalloy Rene'41

Ni-base superalloy Rene'41 was produced by the laser melting deposition (LMD) manufacturing process. The LMD material was solution treated at 1065 °C for 4. h followed by air quenching and aged at 760 °C for 16. h followed by air cooling. Microstructure of the as-deposited, solution treated and solution-aged alloys were characterized by scanning electron microscopy and transmission electron microscopy, and the tensile properties and hardness were tested. The solution-aged Rene'41 superalloy showed high hardness, low strength and low ductility. The extensive precipitation of γ' resulted in high hardness and ductility, and the subsequent alignment and coalescence of γ' precipitates induced low strength. The structure-property relationships of the alloy under three different heat treating conditions were studied and results indicated that the standard heat treatment recommended for wrought Rene'41 was not suitable for LMD alloy and had to be modified to realize optimum mechanical properties.