Effect of thermal ageing on the impact fracture behaviour of Eurofer’97 steel

Ferritic–martensitic reduced activation steel Eurofer’97 is candidate structural material for in-vessel components of proposed fusion reactors. The use of the steel is limited up to a temperature about 550 °C. On the other hand the efficiency enhancement of the fusion reactors to the level suitable for energy production is predetermined by an increase of temperature in reactor. The long-term exposition of the steel at high temperatures leads to microstructural changes. The aim of the work was to investigate the influence of thermal ageing on fracture properties of Eurofer’97 steel. Thermal ageing of the steel was simulated by step cooling treatment. Charpy impact tests were performed before and after thermal ageing. No evident changes in impact properties have been registered when comparing the properties of the steel in as-received state and in state after step cooling.