Review and perspective on fracture toughness testing for pressure vessel steels

摘要

This paper presents a critical review and perspective on fracture toughness testing and its progress for metallic materials. It describes the fracture toughness testing and evaluation of four fracture mechanics parameters, including the elastic stress intensity factor K (or elastic energy release rate G) testing, the. J-integral testing using conventional/standard specimens, the. J-integral testing using small/miniature specimens, the. J-integral testing using full-scale cylindrical vessels, the ductile-to-brittle transition toughness testing (or master curve testing), and the crack-tip opening displacement (CTOD) or crack-tip opening angle (CTOA) testing. Special attention is paid to the standard specimen. J-integral testing that involves the plane strain fracture toughness J_(lc) testing, load-line displacement (LLD) based J-R curve testing, crack mouth opening displacement (CMOD) based J-R curve testing, the normalization method for direct determination of a J-R curve, accurate incremental J-integral equation, and constraint-corrected J-R curve approach for transferring laboratory measured fracture toughness to structural components. In this review, basic experimental estimations, test evaluation procedures, historical efforts, ASTM fracture toughness test standard developments, state-of-the-art progresses and further improvements are overviewed and discussed.