The software of SYSWELD was used to build model and simulate thermal cycle of in-service welding onto active gas pipeline. Influence of pipe diameter, wall thickness and heat input on thermal cycle was studied. The re...The software of SYSWELD was used to build model and simulate thermal cycle of in-service welding onto active gas pipeline. Influence of pipe diameter, wall thickness and heat input on thermal cycle was studied. The results show that t8/5 , t8/3 and peak temperature of inner surface decrease when wall thickness increases from 5 mm to 12 mm. But t8/1 will increases with the increase of wall thickness and will decrease after the wall thickness is larger than 7 mm. Pipe diameter has little influence on thermal cycle and that influence can be ignored when pipe diameter is greater than 273 mm. t8/5 , t8/3 , t8/1 and peak temperature of inner surface will increase with the increase of heat input.展开更多
The effects of some key factors on nitrogen absorption during the smelting process of X70 pipeline steel were studied,and the source of nitrogen pick-up was analyzed to find the bottleneck for nitrogen control.A serie...The effects of some key factors on nitrogen absorption during the smelting process of X70 pipeline steel were studied,and the source of nitrogen pick-up was analyzed to find the bottleneck for nitrogen control.A series of measures were put forward to decrease the nitrogen pick-up.The results indicated that an exponential relationship existed between the nitrogen absorption index and the free oxygen in molten steel.Nitrogen absorption index could decrease below 0.3when free oxygen in molten steel was above 100×10^（-6） after tapping.For low sulfur killed steel,the nitrogen absorption ratio and sulfur content satisfied a linear relationship with a slope of-0.007.Low free-oxygen and sulfur were beneficial to the deep desulfurization during vacuum treatment.The contradiction of high desulfurization ratio and low nitrogen pick-up during LF process could be resolved by skimming oxidizing slag after tapping and making new high basicity top slag.After optimization,the average content of nitrogen in final product decreased from 46×10（-6）to 35×10（-6）.展开更多
基金Sponsored by Scientific Research Fund for Doctors(Y040312)Innovation Fund for Doctors(B2005-3) of China University of Petroleum
文摘The software of SYSWELD was used to build model and simulate thermal cycle of in-service welding onto active gas pipeline. Influence of pipe diameter, wall thickness and heat input on thermal cycle was studied. The results show that t8/5 , t8/3 and peak temperature of inner surface decrease when wall thickness increases from 5 mm to 12 mm. But t8/1 will increases with the increase of wall thickness and will decrease after the wall thickness is larger than 7 mm. Pipe diameter has little influence on thermal cycle and that influence can be ignored when pipe diameter is greater than 273 mm. t8/5 , t8/3 , t8/1 and peak temperature of inner surface will increase with the increase of heat input.
基金Item Sponsored by National Natural Science Foundation of China(51404018)Fundamental Research Funds for the Central Universities of China(FRF-TP-14-125A2)State Key Laboratory of Advanced Metallurgy Foundation of China(KF13-09)
文摘The effects of some key factors on nitrogen absorption during the smelting process of X70 pipeline steel were studied,and the source of nitrogen pick-up was analyzed to find the bottleneck for nitrogen control.A series of measures were put forward to decrease the nitrogen pick-up.The results indicated that an exponential relationship existed between the nitrogen absorption index and the free oxygen in molten steel.Nitrogen absorption index could decrease below 0.3when free oxygen in molten steel was above 100×10^（-6） after tapping.For low sulfur killed steel,the nitrogen absorption ratio and sulfur content satisfied a linear relationship with a slope of-0.007.Low free-oxygen and sulfur were beneficial to the deep desulfurization during vacuum treatment.The contradiction of high desulfurization ratio and low nitrogen pick-up during LF process could be resolved by skimming oxidizing slag after tapping and making new high basicity top slag.After optimization,the average content of nitrogen in final product decreased from 46×10（-6）to 35×10（-6）.
