Precipitation in spray-formed in 718

The precipitation of the gamma ', gamma " and delta phases in a spray-formed version of IN 718 has been studied by hardness measurement and metallographic examination of samples subjected to solution treatment at 1025 degreesC followed by isothermal treatments between 620 and 1010 degreesC up to 100 h. The precipitation processes were compared to those in a wrought (ring-rolled) version of the alloy subjected to the same heat treatments, Time-temperature-hardness diagrams for the two alloys were constructed, Small differences were observed between the two materials but these can at least partly be attributed to differences in composition, For the spray-cast material the delta -phase solvus temperature was determined and the growth kinetics of the gamma " phase established.