A New Ni-Base Superalloy for Oil and Gas Applications

Abstract

A new Ni-base precipitation strengthened alloy has been developed to provide 860 MPa minimum yield strength and an excellent combination of ductility and impact strength. Testing in various corrosive environments has shown that the alloy has excellent stress corrosion and sulfide stress corrosion resistance. A number of commercial heats were melted and processed to establish robust mill processing practice. This paper will talk about the overall alloy development methodology including heat treatment studies to optimize microstructure and target mechanical and corrosion properties to obtain the most cost effective solution to the needs of the oil and gas (O&G) industry.

Time-Temperature-Transformation Diagram of Alloy 945

“…High Cr content and alloying with Mo and Cu makes it suitable for corrosive O&G environments which generally contain high level of chloride, H 2 S, and CO 2 at high temperature low pH acidic conditions with or without S [1,2]. Nb and Ti contents result in precipitation of intermetallic phases γ″ Ni 3 (NbAlTi), and γ′ Ni 3 (AlTi) [3], which are responsible for the high strength required for deep water exploration and production.…”

Formation of L12-ordered precipitation in an alumina-forming austenitic stainless steel via Cu addition and its contribution to creep/rupture resistance

“…Cu is used in many Fe-based and Ni-based alloys for strengthening, corrosion resistance and antibacterial purpose [16,17]. The effect of bcc Cu precipitates on the mechanical properties of ferrite steels attracted special attention for the design of a new type of steel [18][19][20].…”

“…Yamamoto et al [14] developed the L1 2 -ordered Ni 3 (Al,Ti)-strengthened AFA stainless steels based on the knowledge that the addition of Ti improves the stability and formation kinetics of coherent c 0 -Ni 3 (Al,Ti) precipitates which benefit high-temperature mechanical properties in Ni-based and Fe-based superalloys [15]. The degradation in oxidation resistance with Ti can be improved by additions of B and C [14].Cu is used in many Fe-based and Ni-based alloys for strengthening, corrosion resistance and antibacterial purpose [16,17]. The effect of bcc Cu precipitates on the mechanical properties of ferrite steels attracted special attention for the design of a new type of steel [18][19][20].…”

The Influence of Solution Heat Treatment Temperature on the Hardness Response in Incoloy 945

“…Still today, superalloys are commonly used in various fields such as the oil, nuclear and aerospace industries. The Incoloy® 945 was developed in the first decade of this century as a hybrid alloy with a mechanical strength and corrosion resistance comparable to those of Inconel® 718 and Incoloy® 925, respectively, providing 860 MPa in minimum yield strength and a great combination of ductility as well as impact resistance [2]. Its design was specially developed for applications in the oil and natural gas field (O&G).…”