This paper examines some of the properties of Alloy 718 required by the oil and gas industry for the completion of corrosive wells. The properties of interest include strength, toughness, pitting and general corrosion resistance, hydrogen embrittlement resistance, and stress corrosion cracking resistance. The effects of heat treatment on some of these properties are discussed.

Nitrogen (N) has been shown to exert a beneficial influence on localized corrosion resistance of austenitic stainless steels. With duplex stainless steels (SSs), N plays a dual role of controlling the austenite to ferrite ratio and increasing corrosion resistance. In addition, on rapid cooling from high temperatures, N can form deleterious precipitates in the ferrite reducing corrosion resistance. The corrosion resistance and corrosion modes are quite different in N and non-N duplex SSs. These differences are illustrated for a 25%Cr duplex SS.

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