Evaluation of fracture strength and residual life of damaged materials by simulated plasma disruption.

Abstract

In this study, surface damages of type 304 stainless steel, one of the candidates for the first wall structural material in a fusion reactor, at plasma disruption loading are simulated by a high heat flux NBI. Influences of the surface damage on the fracture strength and the residual life are studied. The results obtained are summarized as follows: (1) The present surface damages give a qualitatively good simulation at plasma disruption loading. (2) The fracture strength of the damaged material is improved by the existence of a melting layer which has a higher hardness. There is no effect of microcracks in the melting layer on the fracture strength and the plastic collapse criterion can stand. (3) The fatigue strength of the damaged material is reduced considerably due to the existence of the microcracks in the melting layer. (4) Numerical simulations of fatigue crack growth are successfully attempted. It is shown that the residual life can be predicted quantitatively by the present method.