Mechanical characterisation of a P91 weldment by means of small punch fracture testing

Abstract

Small Punch fracture tests were carried out in order to determine low temperature mechanical behaviour of a P91 steel weldment: weld metal, base metal, Heat Affected Zone-Fine Grained and Heat Affected Zone-Coarse Grained. The Heat Affected Zone-Fine Grained showed superior tensile properties in terms of displacement at fracture (ductility) and strength (maximum force) compared to the other zones, which became more pronounced at lower temperatures, whilst the weld metal exhibited inferior behaviour. Ductile Brittle Transition Temperatures were evaluated from Small Punch results for all zones and the results of base metal and weld metal were correlated with the transition temperatures obtained from Charpy V notch tests according to the CEN Code of Practice for Small Punch testing. Heat Affected Zone-Fine Grained with its finest structure exhibited the lowest transition temperature and the weld metal the highest. Heat Affected Zone-Coarse Grained and base metal were found to have quite similar transition temperature values.