20th International Forgemasters Meeting - IFM 2017

In this work, the effects of solution annealing and aging on an ESR Ni based superalloy are reported. The starting ingot has been hot worked as a rolled ring. The ring has been cut in several chunks, these were heat treated according an experimental design including trial solution annealing and aging at different temperatures and holding times. The microstructure, mechanical properties and durability of the alloy were evaluated after the treatments according the typical requirements for Oil & Gas forgings. The results confirmed the expected increase of secondary carbides at the grain boundaries after the aging, furthermore a γ' morphology change is noticeable. A substantial growth of YS (over 70 ksi) and UTS are obtained only after a long time exposure at the aging temperature, moreover a low temperature impact toughness drop is noted after this heat treatment but the material is able to reach values significantly over the 27 J limit. The aging treatment shows in every case a detrimental effect on the material susceptibility to intergranular corrosion, when tested as per ASTM G28 method A. On the other hand, also after tens of hours at the aging temperature, the pitting corrosion subsequently 24 h in the ASTM G48 method A solution is negligible.