Abstract
Welding and postweld heat-treatment were carried out for low-temperature steel 07MnNiCrMoVDR. Low-temperature impact toughness was tested, the fiber percentage of fracture at different temperature was calculated, macroscopic and microscopic fracture and microstructure were analyzed for base metal, weld seam and heat-affected zone. The results indicate that impact energy of every zone meets requirement of 07MnNiCrMoVDR steel's mechanical property. It also shows that the chosen welding technology and postweld heat-treatment technology are reasonable. Fiber percentage in base metal fracture is higher than that in heat-affected zone fracture and it is the lowest in welded seam fracture through calculation of fracture's fiber percentage. It indicates low-temperature impact toughness of base metal is the highest, and its is higher in heat-affected zone than that in welded seam.