The mechanical behaviour of newly designed low-activation high-chromium martensitic steels

Abstract

Martensitic steels are one of the most promising materials to be used as structural parts in future nuclear fusion machines. The principal problems affecting the behaviour of this type of steels are the mechanical performance and its neutronic activation in the plasma-faced structures. To enhance the connected properties, a new material based on the DIN 1.4914 German steel has been developed. The substitution of minor elements, in order to diminish the neutron activation and at the same time, to improve its strength, is shown in this paper. Two types of materials are taken in consideration with the inclusion of Ta, Ce and Hf elements. The reason for their selection, as well as the mechanical characterization are discussed. Their mechanical characteristics have been based on the microstructural properties of the material under different metallurgical conditions, reached by an extensive thermal treatment program, and includes the determination of the hardness, strength, creep and other properties.