Toughness losses in low alloy steels at high temperatures: an appraisal of certain factors concerning the small punch test

摘要

The present paper deals, at length, with a number of aspects of the novel usage of miniature discspecimens to ascertain the loss of toughness in certain critical engineering components which operateat elevated temperatures. This type of test is commonly known as the small punch, SP, test. Details ofthe experimental methodology are introduced together with a critical appraisal of the relationshipbetween SP transition temperature, T{sub}SP, and the more conventional Charpy fractureappearance transition temperature, FATT, obtained from large test specimens. Essentially it wasdemonstrated that a non-linear expression better described the T{sub}SP-FATT trends published inthe literature, viz. FATT = C/T{sub}(SP){sup}2 When the T{sub}(SP)-FATT trends of the varioussteel classes were concerned separately an encouraging picture emerged in that a reasonable amountof the reported data exhibited good agreement with the predicted effects of grain size. Finally, thefractographic characteristics of the SP test and the Charpy test were compared and contrasted.