2018 年 104 巻 3 号 p. 155-165
In order to develop a simplified evaluation method for brittle crack arrest toughness, correlation between the result of ESSO tests and that of Charpy impact tests was investigated. Charpy impact test specimens with three notch shapes were cut from various steel plates manufactured in a laboratory and a plate mill. The transition temperature determined by the chevron-notch Charpy test correlated better to the results of the ESSO test than those of V-notch or pressed-notch Charpy tests. To determine the cause, an instrumented Charpy test was performed using the V-notch and chevron-notch specimens. As a result, fracture initiation energies of chevron-notch specimens were considerably low irrespective of materials. This indicates that the chevron-notch Charpy test is suitable for evaluating arrest toughness. Furthermore, the transition temperature is linearly related to the square root inverse of the cleavage facet size measured by SEM. Therefore, it is concluded that the chevron-notch Charpy test can be applied to estimate arrest toughness in heavy thick steel plates produced in a plate mill.
