SEPARATION PHENOMENON OF DROP WEIGHT TEAR TEST IN HIGH TOUGHNESS LINEPIPE STEEL

摘要

Although high strength grade steel such as X 120 were widely investigated, X65 to X80 are still the main grades of linepipe steels for the commercial applications. For assurance of high transportation pressure with those kinds of strength grades of steels, thick wall linepipe steels with high toughness are required. As an effective and significant method for evaluating crack arrestability, drop weight tear test (DWTT) results become even more important for those high toughness steels with large thickness. Separation is a commonly seen phenomenon during drop weight tear testing in high toughness linepipe steels. A small amount of separations are believed not to affect the running ductile fracture resistance, while severe separation may be harmful for fracture or burst of pipes. In this paper, the evaluation of separation and the reasons that caused the occurrence of separation in high toughness plate linepipe steels will be discussed.