1989 Volume 38 Issue 428 Pages 472-477
The relation between microstructure and toughness in the weld heat affected zone of SUS329J1 duplex stainless steel has been investigated by means of fractography. The base metal of SUS329J1 had duplex microstructure consisting of α phase and elongated γ phase.
The upper shelf energy in the Charpy impact value versus temperature curve was affected by the location of V notch of Charpy impact specimen. For the specimen in which crack propagation occurred in the short transverse direction, the energy was highest, because of the presence of the platelet and elongated γ phase. The presence of γ phase increased remarkably the toughness for the ductile fracture, but hardly affected the brittle fracture.
As for the microstructure of weld heat affected zone, the specimen heated up to 1373K had the α+γ duplex microstructure and was similar to that of the base metal. The Charpy impact value was also similar to that of the base metal.
For the specimen heated at 1473K and 1573K such as the condition of weld bond region, the toughness considerably decreased, because of the large grain size, the decrease of the volume fraction of γ phase and the precipitation of Cr2N in the α phase.
