UNS N0662 is a nickel-base superalloy used for Oil & Gas applications and commonly produced according to NACE MR0175 in the annealed/solution annealed condition. The annealing/solution annealing treatment makes the material corrosion-resistant in the most challenging environments, in the presence of sulphides and chlorides at high pressure and temperature. However, thanks to its chemical composition, UNS N06625 can also be considered as an age hardenable material, whose mechanical strength can be improved by promoting the metastable second phase γ” precipitation into the γ matrix. However, the corrosion behaviour of the aged alloy has never been investigated in NACE environments. This paper aims to understand the suitability of the age-hardened condition of UNS N06625 for Oil & Gas applications through the evaluation of the material corrosion performance in NACE level VII environments by using NACE TM0177 tests. Three heats of UNS N06625 have been produced and forged in different bar diameters: 152 mm (6 in), 203.2 mm (8 in) and 254 mm (10 in). Afterwards, the bars have been annealed and age-hardened according to optimized time-temperature parameters and finally tested to assess their mechanical properties and resistance to Stress Corrosion Cracking (SCC), Sulphide Stress Cracking

UNS N06625 is a well-known nickel-base superalloy generally used in annealed condition due to its excellent corrosion resistance in the most severe environments containing sulfides and chlorides at high pressure and temperature. In general, the most efficient way to increase the alloy strength is by cold working, but obviously, this cannot be applied in case of large forgings. Actually, looking at its chemical composition, UNS N06625 can be considered an age-hardenable material, whose mechanical strength can be improved by promoting the second phase γ″ precipitation in the matrix. The aim of this paper was to assess the achievable mechanical properties and corrosion resistance of UNS N06625 forged bars in agehardened condition with respect to the annealed one, to understand the feasibility of this not conventional heat treatment for the industrial application. K E Y W O R D S age hardening, corrosion resistance, mechanical strength, second phase γ″, UNS N06625