Mechanical characterization of metallic materials for high temperature reactors in air and in helium environments

The French program of research and development for high temperature reactors which was realised together with General Atomic Company included the study of materials for primary and secondary circuits. In this program, three metallic alloys were considered as reference materials: steel Chromesco 3 with 2,25 % chromium and the alloys 800 H and Hastelloy X. As helium contains some impurities, the corrosion of the metallic materials as well as the evolution of their mechanical characteristics had to be examined. In addition to the corrosion tests realised in helium circuits under pressures of 2 bars and 50 bars (Aida loop), creep tests have been carried out in helium and also in air for Chromesco 3 and alloy 800 H and just in air for Hastelloy X. (Auth.)