Abstract
Within the CPI and other industries, after carbon steel, the 300 series stainless steels have been and will continue to be the "most widely used tonnage" material. The materials of construction for the modern chemical process and petrochemical industries not only have to resist uniform corrosion caused by various corrodents, but must also have sufficient localized corrosion and stress corrosion cracking resistance as well. However in many instances the corrosive conditions are too severe to be handled by commercially available materials including stainless and super stainless steels. Hence the choice to the material specialist has been to utilize more expensive high performance Ni-Cr-Mo alloys. There existed an urgent need to find a cost effective alloy which bridged the cost-performance gap between these two extremes. Over the past 60 years improvements in alloy metallurgy, melting technology, and thermo-mechanical processing, along with a better fundamental understanding of the role of various alloying elements has led to development of alloy 31,UNS N08031 in the mid 1980’s. This advanced super-austenitic high chromium alloy not only bridged this performance gap in a cost effective manner but has also opened new areas of applications. This paper describes the development of this alloy, its physical metallurgy, corrosion resistance characteristics and applications in various industries.
