Static and dynamic fracture toughness of 25 mm thick single edge notch bend (SENB) specimen of C-Mn pressure vessel submerged arc weld metal and flaw assessment under dynamic loading

Abstract
Although there are well established procedures for assessing the significance of defects in welded structures in a number of countries, such as BS7910 and R6 procedures in the UK, the Japanese WES 2807 procedure, the API and MPC procedures in the USA and the recently completed SINT AP procedure resulting from European collaboration, there are no clear guidelines for assessment of the effects of dynamic loading. In principle, the standard procedure can be applied for any rate of loading but there is little or no experience of how to allow for the effects of dynamic loading on load magnitude and material properties. Submerge arc weldments of 100mm thick have been manufactured. The effect of loading rate was investigated by testing 25mm thick SENB specimens. The fracture toughness of the weld metal exhibited marked loading rate sensitivity; shift in fracture toughness transition temperature for high loading rate tests of up to 115 C for 25mm specimens. Finite element (FE) analyses have been carried out to obtain plastic collapse load solutions for SENB fracture mechanics test piece. A simple equation for estimate of dynamic plastic yielding load has been suggested. Flaw assessment under dynamic loading has been demonstrated using the results of dynamic fracture toughness and plastic yiending load. The general methods of assessment of the significance of defects in BS7910 is shown to be applicable to assessments under dynamic loading up to impact.