Treatment of High Temperature Tensile Data for Alloy 617 and Alloy 230

Abstract

Yield strength and tensile strength at temperature are used to set time independent primary stress limits for structural materials in various high temperature design codes. For the Ni-based Alloy 617 and Alloy 230, the temperature trends for the yield strength and tensile strength change significantly above around 1100K and 1025K, respectively, from the lower temperature trends. It is shown that standard methods in obtaining design values for these parameters for Very High Temperature Reactor applications are not satisfactory. Improved methods for the treatment of tensile data are proposed, resulting in more consistent and quantifiable design margin over the full range of low to high temperatures.