THERMAL-SHOCK FRACTURE EXPERIMENTS ON LARGE SIZE PLATES OF A533-B STEEL

The paper gives a complete report on a five-year research program concerning the fracture behaviour of the pressure vessel steel A533-B under thermal shock conditions. Five tests on 140-mm thick plates carrying a surface through-thickness crack were performed with different material conditions and thermal histories. The results confirmed the applicability of the Linear Elastic Fracture Mechanics approach and of the arrest toughness criterion. Moreover, the confidence limits achievable by a material characterization procedure based on Charpy-V tests were assessed. The prevention of crack initiation under a decreasing stress intensity factor and crack-tip temperature ('simple' warm pre-stressing effect) was largely confirmed, while reinitiation prevention after thermal-mechanical histories including complete unloading could not be demonstrated.