Evaluation of PWA1483 for Large single crystal IGT Blade Applications

Abstract

As a part of the Department of Energy "Land Based Turbine Casting Initiative" program, a high chromium containing, corrosion resistant single crystal alloy, PWA1483, was evaluated for large single crystal component application in industrial gas turbines (IGT). The objective of the program was to assess the impact of casting size on casting yield and structural performance of a large anisotropic body. For this purpose, large single crystal blades cast at two different growth rates, were evaluated for crystallographic quality, microstructure, and high angle boundary (HAB) type defects. Presence of HAB defects, is one of the principal factors, contributing to casting rejection. Testing consisted of 649'C tensile, and 76O"C, 871"C, and 982C creep, as a fonction of the deviation of the tensile direction from <OOl>. PWA1483 bicrystals were cast, and tolerance to HAH was evaluated in creep at 760C and 982OC. To assess the potential benefit of minor element additions on HAB tolerance, single crystals and bicrystals of hat%ium and boron modified PWA1483 were also evaluated.