Fracture behaviour of crept P91 welded sample for different post weld heat treatments condition

In the present research work, P91 steel plates of thickness 18 mm were welded using the shielded metal arc welding process. The welded steel plate subjected to different heat treatment condition including post weld heat treatment (760 °C for 2 h, followed by air cooling) and re-austenitizing (1040 °C for 60 min and air cooled) and tempered (760 °C for 2 h, followed by air cooling). The heat treatments were referred as the PWHT and PWNT. The creep sample was prepared to form the welded and heat treated plate. The creep tests were performed at 620 °C for stresses of 150 and 200 MPa. The weld fusion zone and fine-grained heat affected zone of the crept sample were characterized using the field emission scanning electron microscope (FESEM). The fracture surface morphology of crept sample was also studied using the FESEM. The maximum creep exposure time was measured for the PWNT sample as a result of homogeneous microstructure across the weldments.