Behaviour of P91 Steel Simulated Haz at 600°C

Abstract

An investigation has been carried out into the behaviour of type IV cracks region in heat affected zone (HAZ) of P91 steel at 600°C. Microstructure zones where type IV failures may occur have been studied in details. Results are reported on the simulated specimens 11x11x70 mm tested at operating temperature. The results of comparison of mechanical characteristics and microstructure have been analysed using two types of specimens: with postweld heat treatment (PWHT) and without PWHT. It has been found the presence of precipitates at the grain boundaries in simulated type IV zone of HAZ exposed to subsequent PWHT.