GRAIN SIZE INFLUENCE EVALUATION BY SMALL-PUNCH TEST FOR SENSITIZED STAINLESS STEEL IN BWR CONDITIONS

摘要

It is well known than small specimen tests permit the possibility of a good mechanical property evaluation. The small specimens are usually small-scale copies, for instance in the case of tensile test or Charpy test specimen. But some of them have an original shape, like the small-punch test, which uses one of the smaller samples with a size of 3 mm in diameter and 0.25 mm in thickness. Nevertheless, the problem with the very small specimen is that the steel microstructure, like the grain size, may have a high influence on the result scattering than with a standard size sample. So, to evaluate the influence of the grain size on the scattering in BWR conditions, tests with different grain size specimens were performed. It is shown than the grain size and the grain boundary chemistry have no effect on the scattering with our material contrary to the test temperature or the heat treatment for another material. The values of the Weibull shape parameter m are good for this sort of test. It seems difficult to apprehend the value of the shape parameter m without doing a pre-series of test.