Application of Direct Aging to Allvac 718Plus Alloy for Improved Performance

Abstract

Direct aging can result in significant improvement in mechanical properties of many wrought Nibase superalloys. Its effectiveness is closely related to hot working and aging conditions and is also alloy-dependent. This process is most often used with γ" rather than γ' strengthening alloys.Allvac ® 718Plus™ alloy is predominantly a γ' strengthening alloy which shows excellent mechanical properties and high thermal stability up to 704°C in the solution treated and aged condition. It was uncertain if direct aging could be effective in this alloy. A test program was initiated to explore if direct aging could improve the alloy's performance and to determine the optimum process conditions. The variables evaluated included forging temperature, forging reduction, forging heating time and post-forging cooling rate. Mechanical tests and microstructural study after different direct aging treatments demonstrated that direct aging is feasible at a production scale for alloy 718Plus and a significant improvement in performance can be achieved under well-controlled conditions. The mechanism responsible for such improvement is briefly discussed.

Sputtered Ni‐Base Superalloys for Microscale Devices

“…The XRD pattern for the foils heated to 1000°C indicates the dissolution of the orthorhombic δ-Ni 3 Nb phase. This result is consistent with reports of the δ solvus temperature being approximately 1000°C [8,9]. The Ni (222) double peak was even more pronounced after heat treating at 1000°C pointing to an increased volume fraction of γ'-Ni 3 Al precipitates.…”

Effect of Strain Hardening on Precipitation Kinetics in ATI 718Plus

“…It is known that grain boundary precipitation can, in small amounts, reduce high temperature notch sensitivity [8], resist intergranular crack propagation and improve grain size control during hot working operations [9]. Although, excessive amounts of δ phase are detrimental to the alloys' mechanical properties [7].…”