Effect of heat treatment on the combination stress-rupture properties of allvac 718plus™

The effect of heat treatment on the combination stress-rupture (CSR) properties of Allvac 718Plus™ is reported. Two heat treatments were given to 718Plus in the as-forged condition to determine the effect of heat treatment on the susceptibility of this alloy to grain-boundary cracking and rupture during subsequent testing of CSR samples. The heat treatments employed were (1) the standard heat treatment developed by General Electric Aircraft Engines (GEAE) for this alloy and (2) a treatment suggested by Allvac which precedes the GEAE heat treatment to reduce the susceptibility to grain-boundary cracking. The results suggest that processing most likely has a much larger effect on the susceptibility of this alloy to grain-boundary cracking than heat treatment alone. Microstructural features which may increase resistance to gas-phase embrittlement, and grain-boundary cracking are discussed.