Header menu link for other important links
Role of evolving microstructure on the mechanical behaviour of P92 steel welded joint in as-welded and post weld heat treated state
, M. Mohan Mahapatra, P. Kumar, J.G. Thakre, N. Saini
Published in Elsevier Ltd
Volume: 263
Pages: 241 - 255
An autogenous gas tungsten arc welded P92 weld joint was subjected to two different post weld heat treatment (PWHT). One PWHT involved tempering of the as-welded sample at 760 °C for 2 h (referred to as PWDT) followed by natural air cooling. The other PWHT involved normalizing (re-austenitizing) the as-welded sample at 1040 °C for 40 min followed by PWDT (referred as PWNT). The cross-section of the as-welded sample exhibited a higher degree of microstructural heterogeneity. Both the PWDT and PWNT heat treatment procedures reduced the heterogeneity gradient along the weld cross section. The heat affected zone (HAZ) of the as-welded and PWDT samples showed Charpy toughness values of 3 ± 4 J and 64 ± 6 J, respectively, which were lower than that of the base metal (72 ± 5 J). The PWNT treated sample exhibited a HAZ Charpy toughness value of 83 ± 4 J which was higher than that of the base metal. The brittle mode of the fracture with river patterns was observed for the as-welded and PWDT treated sample while a ductile mode of fracture with fine and shallow dimples was observed for the PWNT condition. The PWNT treatment resulted in dissolution of the ferrite patches and formation of a uniform microstructure along the weld cross section. The PWNT treated samples exhibited the lowest yield strength to tensile strength ratio supporting the enhanced ductility as a result of this re-austenizing heat treatment. The as-welded and PWDT treated weld joints showed the presence of detrimental δ ferrite phase in the weld fusion zone and the coarse grained heat affected zone. The PWNT completely removed the δ ferrite patches from the microstructure whereas the PWDT treatment merely reduced the range of the hardness of the δ ferrite from 179 to 301 HV (as welded) to 204–228 HV. © 2018 Elsevier B.V.
About the journal
JournalData powered by TypesetJournal of Materials Processing Technology
PublisherData powered by TypesetElsevier Ltd