Self-restrained testing for residual stress driven cracking in nickel-based alloys

The use of nickel-based superalloys in the hottest sections of coal-fired power plants would enable efficiency gains and emissions reductions. In order to study the effect of residual stress on cracking susceptibility in some candidate superalloys, compact tension samples were pre-strained in compression beyond yield and tested without additional external loading. The testing parameters pre-strain and temperature were investigated and were found to have a minor effect on cracking relative to microstructure. The microstructural factors which had the strongest effect on crack length were grain size and degree of intragranular gamma prime precipitation.