Environmental behavior of low thermal expansion inconel® alloy 783

Abstract

The chloride corrosion resistance of low thermal expansion INCONEL® alloy 783, was determined by 1,000 hour salt spray exposure tests. Selected samples were also intermittently exposed to 650°C during salt spray testing. The objective of this investigation was to understand the corrosion resistance of 783 as compared to alloys 909, 718, and a martensitic stainless steel, M152, in marine environments. Testing was performed on as-machined, pre-oxidized, and chromide coated material conditions. Results indicate that alloy 783 provides chloride corrosion resistance similar to 718, a significant improvement over both alloy 909 and M152. In addition, the processing schedule of alloy 783 is more amenable to chromide coating. Performance of coated alloy 783 was also on par with that of coated alloy 718. Alloy behavior and preliminary assessment of scale constituents are presented for selected testing and base metal conditions.