16-8-2 and Other Weld Metal Compositions that Utilize Controlled Residual Elements to Enhance and Maintain Elevated Temperature Creep Strength

Achieving high temperature creep strength while maintaining rupture ductility in weld metal for austenitic stainless steel weldments has always been challenging. In the late 1940's and early 1950's, independent work in both Europe and the USA resulting in what is known today as the 16-8-2 (nominally 16% chromium -8% nickel -2% molybdenum) stainless steel weld metal. Philo 6 and shortly thereafter at Eddystone used the alloy to construct the first supercritical boilers and piping in the USA. Concurrent with domestic boiler and piping fabrication, the US Navy was also using this material for similar supercritical applications. Over the decades, enhanced performance has evolved with variations of the basic composition and by adding specific residual elements. Controlled additions of P. B, V, Nb and Ti have been found to greatly enhance elevated temperature as well as cryogenic behavior. The history of these developments, example compositions and areas of use as well as mechanical property results are presented.