The microstructure and the characteristics of the inclusions embedded in ferrite matrix in simulated coarse-grain heat affected zone (CGHAZ) of a Ti-Zr-treated high strength low alloy (HSLA) steel have been investigat...The microstructure and the characteristics of the inclusions embedded in ferrite matrix in simulated coarse-grain heat affected zone (CGHAZ) of a Ti-Zr-treated high strength low alloy (HSLA) steel have been investigated. The microstructure of the simulated CGHAZ dominantly consisted of intragranular acicular ferrite (IAF) combining with a small amount of polygonal ferrite (PF), widmanst tten ferrite (WF), bainite ferrite (BF), pearlite and martensite-austenite (M-A) islands. The PF, WF and BF were generally observed at the prior austenite grain boundaries and the interlocking acicular ferrite was usually found intragranularly. It was found that the inclusions were composed of Ti2O3, ZrO2, Al2O3 locating at the center of the particles and MnS lying on the surface layer of the inclusions. The intragranular complex inclusions promoted the acicular ferrite formation and the refinement of microstructure whilst those at prior austenite grain boundaries caused PF formation on the inclusions. The simulated CGHAZ consisting of such complicated microstructure exhibited desired mechanical properties.展开更多
A hybrid neural network model,in which RH process(theoretical)model is combined organically with neural network(NN)and case-base reasoning(CBR),was established.The CBR method was used to select the operation mode and ...A hybrid neural network model,in which RH process(theoretical)model is combined organically with neural network(NN)and case-base reasoning(CBR),was established.The CBR method was used to select the operation mode and the RH operational guide parameters for different steel grades according to the initial conditions of molten steel,and a three-layer BP neural network was adopted to deal with nonlinear factors for improving and compensating the limitations of technological model for RH process control and end-point prediction.It was verified that the hybrid neural network is effective for improving the precision and calculation efficiency of the model.展开更多
The influence of flow control devices on metallurgical effects in alarge-capacity tundish has been studied carefully with elements tracing, sampling and theoreticalprospecting. The results from the studies arc (1) in ...The influence of flow control devices on metallurgical effects in alarge-capacity tundish has been studied carefully with elements tracing, sampling and theoreticalprospecting. The results from the studies arc (1) in the continuous casting of clean steel, badcontrol of tundish operation may deteriorate the cleanliness of steel; (2) the cleanliness of steelis deteriorated mainly at the unsteady state; (3) large amount of macro inclusions come from the topslag and the refractory of tundish; (4) installing dam and weir can improve the cleanliness ofsteel and lighten the influence of steel fluctuation; and (5) the result of theoretical calculationsuggests that the inclusions larger than the critical size of 92.6 mu m can be floated out from thetundish bath completely.展开更多
The total oxygen content and the behavior of non-metallic inclusions were studied systematically for steel Q345 D.The production process of steel Q345 Dis BOF→argon stirring in ladle→slab casting at Wuhan Iron and S...The total oxygen content and the behavior of non-metallic inclusions were studied systematically for steel Q345 D.The production process of steel Q345 Dis BOF→argon stirring in ladle→slab casting at Wuhan Iron and Steel(Group)Co.The following results were obtained:the total oxygen of slab is 0.000 9 %-0.001 2%,and the number of micro-inclusions is 1.63-2.03mm-2,while the amount of the macro-inclusions in one kilogram steel is 0.495 mg.展开更多
文摘The microstructure and the characteristics of the inclusions embedded in ferrite matrix in simulated coarse-grain heat affected zone (CGHAZ) of a Ti-Zr-treated high strength low alloy (HSLA) steel have been investigated. The microstructure of the simulated CGHAZ dominantly consisted of intragranular acicular ferrite (IAF) combining with a small amount of polygonal ferrite (PF), widmanst tten ferrite (WF), bainite ferrite (BF), pearlite and martensite-austenite (M-A) islands. The PF, WF and BF were generally observed at the prior austenite grain boundaries and the interlocking acicular ferrite was usually found intragranularly. It was found that the inclusions were composed of Ti2O3, ZrO2, Al2O3 locating at the center of the particles and MnS lying on the surface layer of the inclusions. The intragranular complex inclusions promoted the acicular ferrite formation and the refinement of microstructure whilst those at prior austenite grain boundaries caused PF formation on the inclusions. The simulated CGHAZ consisting of such complicated microstructure exhibited desired mechanical properties.
基金Item Sponsored by National Natural Science Foundation of China(50074026)
文摘A hybrid neural network model,in which RH process(theoretical)model is combined organically with neural network(NN)and case-base reasoning(CBR),was established.The CBR method was used to select the operation mode and the RH operational guide parameters for different steel grades according to the initial conditions of molten steel,and a three-layer BP neural network was adopted to deal with nonlinear factors for improving and compensating the limitations of technological model for RH process control and end-point prediction.It was verified that the hybrid neural network is effective for improving the precision and calculation efficiency of the model.
文摘The influence of flow control devices on metallurgical effects in alarge-capacity tundish has been studied carefully with elements tracing, sampling and theoreticalprospecting. The results from the studies arc (1) in the continuous casting of clean steel, badcontrol of tundish operation may deteriorate the cleanliness of steel; (2) the cleanliness of steelis deteriorated mainly at the unsteady state; (3) large amount of macro inclusions come from the topslag and the refractory of tundish; (4) installing dam and weir can improve the cleanliness ofsteel and lighten the influence of steel fluctuation; and (5) the result of theoretical calculationsuggests that the inclusions larger than the critical size of 92.6 mu m can be floated out from thetundish bath completely.
文摘The total oxygen content and the behavior of non-metallic inclusions were studied systematically for steel Q345 D.The production process of steel Q345 Dis BOF→argon stirring in ladle→slab casting at Wuhan Iron and Steel(Group)Co.The following results were obtained:the total oxygen of slab is 0.000 9 %-0.001 2%,and the number of micro-inclusions is 1.63-2.03mm-2,while the amount of the macro-inclusions in one kilogram steel is 0.495 mg.
