WES 2808 for brittle fracture assessment of steel components under seismic conditions Part III: Change in CTOD fracture toughness of structural steels by pre-strain and dynamic loading

Abstract It has been reported that dynamic and cyclic large deformation the main factor, and as for the brittle fracture of the weld steel structure at the Hanshin-Awaji earthquake in 1995. As for this issue, fracture toughness deteriorates by the change in tensile properties of the steel materials by the dynamic and/or cyclic strain, and it is thought that fracture was initiated from weld defects. Fracture toughness change due to dynamic and/or cyclic strain was quantified at FTE Committee in Japan welding engineer society (JWES), and the result is taken in an assessment procedure standard of WES2808(2003). Thereafter, the FTE committee examined the expansion of application steel materials continuously and was able to adapt HT780 as a target range in this standard revision. In this report, a temperature shift concept that is the basic of the fracture toughness evaluation of WES2808 is described the influence of the dynamic loading and pre-strain. And it is included the comparison of strain-history effect such as monotonic vs. cyclic strain and tensile vs. compressive strain. In addition, it is examined the influence of the dynamic and pre-strain history on fracture toughness change for HT780 and confirmed that a temperature shift equations in WES2808 (2003) can be applicable to HT780 steel.