Comprehensive pre-test material characterisation: results of the characterisation of the HAZ and the cladding in view of ductile fracture of the NESC1 1 spinning cylinder

摘要

The NESC 1 spinning cylinder experiment is aimed at studying the entire process of structural integrity assessment of under-clad and through-clad cracks in PWR vessel steels. A spinning cylinder was subjected to conditions of pressurised thermalshock. Several Task Groups have been working on inspection, material properties, fracture mechanics, instrumentation, and overall evaluation. The failure event of the cylinder in the test was postulated to he cleavage followed by arrest. Determination ofthe mechanical and physical material properties of the forging, the cladding and the HAZ was required as an input to the thermal stress analysis and to the fracture mechanics analysis. Therefore, an extensive material characterisation programme wasperformed by eight European organisations.Data for thermal stress analysis comprised a literature review and experiments of thermal elastic material properties as well as tensile tests separately on cladding, HAZ, and base metal. Tensile properties and ductile behaviour in terms of fractureresistance (J-△a) curves were measured at temperatures ranging from RT to 300°C. Several specimen types (cylindrical, rectangular tensile specimens, CT, and 3PB) with dimensions ranging from standard to miniature were used to characterise the variationof the material properties, particularly for the HAZ (5 to 10mm thickness) and the cladding (two layers, 10mm thickness). The irradiation behaviour of the cladding material was verified with an irradiation and post-irradiation testing experiment tojustify the simulation of RPV EOL.The paper presents the test results and the analysis of the variation of deformation and fracture behaviour of the various material layers, focusing on the ductile fracture behaviour of the NESC cylinder.