Mechanical and Microstructural Characterization of Forged Inconel 625 Ring Gaskets for Oil and Gas Application

Abstract

Abstract The need for mechanical components that perform well in critical service conditions pushed industrial research to develop materials with an excellent combination of mechanical and corrosion resistance. Among these new materials are nickel alloys and duplex stainless steels, which play primary roles in many engineering fields, especially in the oil and gas industries, in which the use of pipes, flanges, and gaskets is very common. In the international standards, much attention is paid to the first two components, but less information is available about gaskets and their behavior during the tightening operation. Standards generally require a maximum hardness for the gasket, even if this parameter is not sufficient to describe the whole plastic behavior of the material. In this experimental work, two forged Inconel 625 rings were investigated: one was delivered in the as-forged condition, whereas the second was solubilized at 1,150°C. The soaking time at such a temperature must be carefully studied in order to get a homogeneous temperature field in the whole component and to obtain a decrease of the as-forged hardness as required by the standards. For such a reason, tests will be performed to study the grain growth and the hardness evolution varying the soaking time at 1,150°C. Finally, the tensile and compression properties will be studied to determine the stress-strain behavior of the alloy in the elastic and plastic fields.