The Elevated Temperature and Thermal Shock Fracture Toughnesses of Nuclear Pressure Vessel Steel

Abstract

Thermal shock experiments were conducted on nuclear pressure vessel steel A533 Grade B Class 1. Elastic-plastic fracture toughness tests were carried out within the same high temperature range of the thermal shock experiment and the relation between stretched zone width, SZW and J-integral was clarified. An elastic-plastic thermal shock fracture toughness value, J_tsc was evaluated from a critical value of stretched zone width, SZW_tsc at the initiation of thermal shock fracture by using the relation between SZW and J. The J_tsc value was compared with elastic-plastic fracture toughness values, J_Ic, and the deference between the J_tsc and J_Ic values was discussed.
The results obtained are summarized as follows;
(1) The relation between SZW and J before the initiation of stable crack growth in fracture toughness test at a high temperature can be expressed by the following equation regardless of test temperature,
SZW=95(J/E),
where E is Young's modulus.
(2) Elevated temperature fracture toughness values ranging from room temperature to 400°C are nearly constant regardless of test temperature. It is confirmed that upper shelf fracture toughness exists.
(3) Thermal shock fracture toughness is smaller than elevated temperature fracture toughness within the same high temperature range of thermal shock experiment.