B2O3 is selected as fluxing agent of CaO-based ladle refining slag to decrease the melting temperature as well as to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting te...B2O3 is selected as fluxing agent of CaO-based ladle refining slag to decrease the melting temperature as well as to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature of two series of refining slags including the low basicity slags （the mass ratio of CaO/SiO2 is 3--4） and the high basicity slags （the mass ratio of CaO/SiO2 is 5--8.75） were investigated. The slag melting temperature was meas- ured using the hemisphere method. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and A1203. For the CaO-based refining slag with low basicity, the melting temperature is decreased effectively when B2O3 is used to substitute for equal mass of CaF2, Al2O3 and SiO2, respectively. For the CaO-based refining slag with high basicity, when CaF2 is substituted by B2 03, the melting temperature can be decreased remarkably. Espe- cially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in the range of 1.1--4.0 and 5.25--8. 0, respectively, the slag melting temperature is lower than 1 300 ℃. Therefore, the 132 03-containing refining slags with high ratios of CaO/Al2O3 and CaO/SiO2 have ultra low melting temperature.展开更多
To avoid slag sticking on the ladle immersion cover during the LATS refining and alloying process, the effect of Al2O3 on the melting point of the ladle slag was studied and the additives including CaF2, B2O3, Li2O, a...To avoid slag sticking on the ladle immersion cover during the LATS refining and alloying process, the effect of Al2O3 on the melting point of the ladle slag was studied and the additives including CaF2, B2O3, Li2O, and CaO were used to decrease the melting point of the ladle slag. The melting point was measured using the hemisphere method. The results show that the addition of Al2O3 to the ladle slag increases the melting point. The fluxing action is not remarkable if only CaF2 or CaO is used as the additive. The fluxing action of the composite additive obtained by the mixing of CaO and CaF2 in the mass proportion of ωCaO：ωCaF2=2 ： 1 is preferred. The fluxing action of B2O3 is also notable. When the B2O3 content in mass percent is in the range from 2% to 10%, the corresponding melting point is 1 380 ℃ to 1 290℃. The fluxing action of Li2O is the most remarkable. When the Li2O content is up to 5%, the melting point of the slag is lower than 1 300 ℃.展开更多
The application of rare earths(RE) in the Ni saving heat resistant steel was studied by metalloscopy,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray difference(XRD).Because the diffusion of...The application of rare earths(RE) in the Ni saving heat resistant steel was studied by metalloscopy,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray difference(XRD).Because the diffusion of chromium was promoted by RE,a dense and adhesive Cr2O3 layer could form rapidly at the early oxidation stage,which played a effective protection role;the pinning effect of silicon dioxide was enhanced by RE in the internal oxidation layer,which had a block effect on the diffusion of metal ions and oxygen ions at later stage of oxidation and resulted in that the high temperature oxidation rate of RE heat resistant steel was decreased.展开更多
True stress?true strain curves of Incoloy028alloy at high temperature and strain rate were investigated by hot compression test.These curves show that the maximum flow stress decreases with the increase in temperature...True stress?true strain curves of Incoloy028alloy at high temperature and strain rate were investigated by hot compression test.These curves show that the maximum flow stress decreases with the increase in temperature and the decrease in strain rate.FEM simulation was employed to investigate the influence of temperature,extrusion speed and friction coefficient on the extrusion load,stress,strain and strain rate in the extrusion process.The increase of extrusion temperature results in decrease of load and deformation resistance,but has little influence on strain and strain rate.When extrusion speed changes between200and350mm/s,no obvious change about extrusion load can be found.Sharp peak value up to42500kN emerges in the extrusion load curve and the extrusion process becomes unstable seriously when extrusion speed rises up to400mm/s.Both stress and strain rate increase with the raise of extrusion speed.When friction coefficient is between0.02and0.03,deformation resistance is about160MPa and the strain rate can be limited below70s?1.Successful production of Incoloy028tube verifies the optimized parameters by FEM simulation analysis,and mechanical tests results of the products meet the required properties.展开更多
304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger(PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped s...304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger(PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped stainless steel. Finite element method simulation is herein used to analyze metal flow characteristics, optimize the extrusion die, and predict the extrusion force at different temperatures and speeds. A Φ400-mm container and Φ388-mm forging billet are selected, and the 304L H-shaped stainless steel is successfully manufactured using a Germany SMS 60 MN horizontal extruder. The mechanical properties and microstructure of the manufactured 304L H-shaped stainless steel meet the requirements of the PRHR HX, and the surfaces of the product pass the dye penetration test. The H-shaped stainless steels are used in Haiyang nuclear power plant in Shandong Province.展开更多
The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribu...The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribution of copper-rich precipitates by different annealing processes were characterized by scanning electron microscopy,transmission electron microscopy,backscatter electron and backscatter diffraction.The pitting resistance behavior in simulated physiological saline envi-ronments(0.9 wt.%NaCl)was investigated using electrochemical workstation and X-ray photoelectron spectroscopy.The results showed that the copper-rich phase prepared by repeated rolling and annealing gradually changed from long needle-like to short thick rod-like and granular,whose distribution tended to be uniform and diffusive,and the number of copper-rich phases increased.After solution/antibacterial annealing process,the size and density of the copper-rich phase increase,resulting in a discontinuity of the passivation film on the stainless steel,which reduces the pitting resistance to some extent.The refinement mechanism revealed that pre-deformation brings about a modification in both precipitation mechanism and growth kinetics of epsilon copper.展开更多
In order to better understand the relation between grain boundary characteristic distribution （GBCD） and the brittle cracking of ferritic stainless steel, the GBCD, impact test and bend test were investigated using ...In order to better understand the relation between grain boundary characteristic distribution （GBCD） and the brittle cracking of ferritic stainless steel, the GBCD, impact test and bend test were investigated using scanning electron microscopy （SEM） and the electron backscatter diffraction （EBSD） technique. The results show that a crack occurs preferentially at high angle boundaries, and that low angle and low-∑ coincidence site lattice（CSL） boundaries can offer resistance to the propagation of cracks. It is suggested that an optimum GBCD, i.e. a high frequency of low angle or low-∑ CSL boundaries and discontinuous high angle boundaries network can offer the potential for decreasing the ductile-to-brittle transition temoerature （DBTT） of ferritic stainless steels.展开更多
Mn is a weak element for austenite formation and its effect on martensitic stainless steel is seldom researched. The microstructure and property of 13Cr martensitic stainless steel with varied Mn content and low carbo...Mn is a weak element for austenite formation and its effect on martensitic stainless steel is seldom researched. The microstructure and property of 13Cr martensitic stainless steel with varied Mn content and low carbon content were studied. The research demonstrates that Mn enlarges the austenitic zone at a high temperature and increases the strength and hardness of martensitic stainless steel. Following the addition of Mn,the corrosion resistance property of low carbon 13Cr stainless steel only decreases slightly. The strength and hardness of low carbon 13Cr stainless steel containing Mn is similar to that of high carbon 13Cr stainless steel.展开更多
A formula of calculating curvature radius was deduced according to the theory of rolling, together with the characteristics of rolling process. Moreover, the simulation of producing process is represented. Simulating ...A formula of calculating curvature radius was deduced according to the theory of rolling, together with the characteristics of rolling process. Moreover, the simulation of producing process is represented. Simulating results indicate that the curvature radius could be reduced by increasing friction coefficient, friction coefficient ratio, reduction or roller radius, while it could be augmented by increasing the thickness of plate. Furthermore, increasing the thickness of plate would cause more effects on front end curvature, whereas reduction would do less. The result provides theoretic basis for eliminating the front end curvature in plate and sheet rolling process, and it is important to protect controlling equipment and reduce scrap as well.展开更多
A high blast temperature is an effective measure that improves pulverized coal injection （PCI）and energy consumption,decreases the cost of blast furnaces （BF）. Apart from using technology such as the increased vau...A high blast temperature is an effective measure that improves pulverized coal injection （PCI）and energy consumption,decreases the cost of blast furnaces （BF）. Apart from using technology such as the increased vault temperature of the hot-blast stove, the increased temperature of the waste gas, the preheating of combustion air and gas, and fully closed mixed air valves, other measures, such as using an oxygen-enriched blast stove, burning high heating value converter gas, increasing the number of stove changes to reduce the time needed for stove blasts, were taken to increase the blast temperature of the 2 500 m3 BF in recent years. The blast temperature of the 2 500 m3 BF was continuously increased in these years. The monthly average temperature of the 2 500 m3 BF reached 1 158℃, with the highest blast temperature reaching 1 195 ℃ in 2006. This technique of increased blast temperatures has reached an advanced level in China.展开更多
Based on the existing technology and equipment for stainless steel production, the smelting process of ferritic stainless steel in the argon-oxygen decarburization （AOD） furnace using blast furnace （BF）molten iron...Based on the existing technology and equipment for stainless steel production, the smelting process of ferritic stainless steel in the argon-oxygen decarburization （AOD） furnace using blast furnace （BF）molten iron （after dephosphorization） and ferrochrome alloy is studied and discussed. In the new process,phosphorus and other harmful elements are reduced to a lower level （P≤0. 020% ） when smelting ferritic stainless steel. With this process,both production flexibility and efficiency are enhanced. As no electric furnace is used in the smelting, the production cost is lowered with a great deal of electric power saved, while the total yield of chromium is increased.展开更多
To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refinin...To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refining ladle slag. The effect of CaO-CaF2 on the melting point, viscosity, and desulfurizing capability of the ladle slag was investigated. The melting point of the unmodified ladle slag is 1439℃. When adding 20wt% CaO-CaF2, the melting point is decreased to 1327℃. At 1500℃. the viscosity of the unmodified ladle slag is 6.5 Pa.s, which can be decreased lower than 2 Pa.s by adding more than 10wt% CaO-CaF2. The experimental results of desulfu- rization of the melts show that the desulfurizing power of the ladle slag can be enhanced by adding CaO-CaF2.展开更多
基金Item Sponsored by National High Technology Research and Development Program(863 Program)of China(2007AA03Z548)Natural Science Foundation of Jiangsu Province of China(BK2010355)
文摘B2O3 is selected as fluxing agent of CaO-based ladle refining slag to decrease the melting temperature as well as to improve the speed of slag forming and the refining efficiency. The effects of B2O3 on the melting temperature of two series of refining slags including the low basicity slags （the mass ratio of CaO/SiO2 is 3--4） and the high basicity slags （the mass ratio of CaO/SiO2 is 5--8.75） were investigated. The slag melting temperature was meas- ured using the hemisphere method. The results indicate that the fluxing action of B2O3 is better than that of CaF2 and A1203. For the CaO-based refining slag with low basicity, the melting temperature is decreased effectively when B2O3 is used to substitute for equal mass of CaF2, Al2O3 and SiO2, respectively. For the CaO-based refining slag with high basicity, when CaF2 is substituted by B2 03, the melting temperature can be decreased remarkably. Espe- cially, when the mass ratios of CaO/Al2O3 and CaO/SiO2 are in the range of 1.1--4.0 and 5.25--8. 0, respectively, the slag melting temperature is lower than 1 300 ℃. Therefore, the 132 03-containing refining slags with high ratios of CaO/Al2O3 and CaO/SiO2 have ultra low melting temperature.
基金Item Sponsored by National Natural Science Foundation of China (50474037) Natural Science Foundation of Jiangsu Higher Education Institutions of China (04KJB430022 ,05KJD450043)
文摘To avoid slag sticking on the ladle immersion cover during the LATS refining and alloying process, the effect of Al2O3 on the melting point of the ladle slag was studied and the additives including CaF2, B2O3, Li2O, and CaO were used to decrease the melting point of the ladle slag. The melting point was measured using the hemisphere method. The results show that the addition of Al2O3 to the ladle slag increases the melting point. The fluxing action is not remarkable if only CaF2 or CaO is used as the additive. The fluxing action of the composite additive obtained by the mixing of CaO and CaF2 in the mass proportion of ωCaO：ωCaF2=2 ： 1 is preferred. The fluxing action of B2O3 is also notable. When the B2O3 content in mass percent is in the range from 2% to 10%, the corresponding melting point is 1 380 ℃ to 1 290℃. The fluxing action of Li2O is the most remarkable. When the Li2O content is up to 5%, the melting point of the slag is lower than 1 300 ℃.
文摘The application of rare earths(RE) in the Ni saving heat resistant steel was studied by metalloscopy,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray difference(XRD).Because the diffusion of chromium was promoted by RE,a dense and adhesive Cr2O3 layer could form rapidly at the early oxidation stage,which played a effective protection role;the pinning effect of silicon dioxide was enhanced by RE in the internal oxidation layer,which had a block effect on the diffusion of metal ions and oxygen ions at later stage of oxidation and resulted in that the high temperature oxidation rate of RE heat resistant steel was decreased.
基金Project(50925417)supported by the National Science Fund for Distinguished Young Scholars of China
文摘True stress?true strain curves of Incoloy028alloy at high temperature and strain rate were investigated by hot compression test.These curves show that the maximum flow stress decreases with the increase in temperature and the decrease in strain rate.FEM simulation was employed to investigate the influence of temperature,extrusion speed and friction coefficient on the extrusion load,stress,strain and strain rate in the extrusion process.The increase of extrusion temperature results in decrease of load and deformation resistance,but has little influence on strain and strain rate.When extrusion speed changes between200and350mm/s,no obvious change about extrusion load can be found.Sharp peak value up to42500kN emerges in the extrusion load curve and the extrusion process becomes unstable seriously when extrusion speed rises up to400mm/s.Both stress and strain rate increase with the raise of extrusion speed.When friction coefficient is between0.02and0.03,deformation resistance is about160MPa and the strain rate can be limited below70s?1.Successful production of Incoloy028tube verifies the optimized parameters by FEM simulation analysis,and mechanical tests results of the products meet the required properties.
基金supported by the State Key Laboratory for Mechanical Behavior of Materials(No.20171909)
文摘304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger(PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped stainless steel. Finite element method simulation is herein used to analyze metal flow characteristics, optimize the extrusion die, and predict the extrusion force at different temperatures and speeds. A Φ400-mm container and Φ388-mm forging billet are selected, and the 304L H-shaped stainless steel is successfully manufactured using a Germany SMS 60 MN horizontal extruder. The mechanical properties and microstructure of the manufactured 304L H-shaped stainless steel meet the requirements of the PRHR HX, and the surfaces of the product pass the dye penetration test. The H-shaped stainless steels are used in Haiyang nuclear power plant in Shandong Province.
基金support of this work by the National Natural Science Foundation of China(51774226)the Major Program of Science and Technology in Shanxi Province(No.20191102006).
文摘The effects of different annealing processes on the phase precipitation behavior and corrosion properties of copper-bearing 430 ferritic stainless steel were systematically investigated.The shape,quantity and distribution of copper-rich precipitates by different annealing processes were characterized by scanning electron microscopy,transmission electron microscopy,backscatter electron and backscatter diffraction.The pitting resistance behavior in simulated physiological saline envi-ronments(0.9 wt.%NaCl)was investigated using electrochemical workstation and X-ray photoelectron spectroscopy.The results showed that the copper-rich phase prepared by repeated rolling and annealing gradually changed from long needle-like to short thick rod-like and granular,whose distribution tended to be uniform and diffusive,and the number of copper-rich phases increased.After solution/antibacterial annealing process,the size and density of the copper-rich phase increase,resulting in a discontinuity of the passivation film on the stainless steel,which reduces the pitting resistance to some extent.The refinement mechanism revealed that pre-deformation brings about a modification in both precipitation mechanism and growth kinetics of epsilon copper.
文摘In order to better understand the relation between grain boundary characteristic distribution （GBCD） and the brittle cracking of ferritic stainless steel, the GBCD, impact test and bend test were investigated using scanning electron microscopy （SEM） and the electron backscatter diffraction （EBSD） technique. The results show that a crack occurs preferentially at high angle boundaries, and that low angle and low-∑ coincidence site lattice（CSL） boundaries can offer resistance to the propagation of cracks. It is suggested that an optimum GBCD, i.e. a high frequency of low angle or low-∑ CSL boundaries and discontinuous high angle boundaries network can offer the potential for decreasing the ductile-to-brittle transition temoerature （DBTT） of ferritic stainless steels.
文摘Mn is a weak element for austenite formation and its effect on martensitic stainless steel is seldom researched. The microstructure and property of 13Cr martensitic stainless steel with varied Mn content and low carbon content were studied. The research demonstrates that Mn enlarges the austenitic zone at a high temperature and increases the strength and hardness of martensitic stainless steel. Following the addition of Mn,the corrosion resistance property of low carbon 13Cr stainless steel only decreases slightly. The strength and hardness of low carbon 13Cr stainless steel containing Mn is similar to that of high carbon 13Cr stainless steel.
基金Item Sponsored by Natural Science Foundation of Shaanxi Province of China (2004E19)
文摘A formula of calculating curvature radius was deduced according to the theory of rolling, together with the characteristics of rolling process. Moreover, the simulation of producing process is represented. Simulating results indicate that the curvature radius could be reduced by increasing friction coefficient, friction coefficient ratio, reduction or roller radius, while it could be augmented by increasing the thickness of plate. Furthermore, increasing the thickness of plate would cause more effects on front end curvature, whereas reduction would do less. The result provides theoretic basis for eliminating the front end curvature in plate and sheet rolling process, and it is important to protect controlling equipment and reduce scrap as well.
文摘A high blast temperature is an effective measure that improves pulverized coal injection （PCI）and energy consumption,decreases the cost of blast furnaces （BF）. Apart from using technology such as the increased vault temperature of the hot-blast stove, the increased temperature of the waste gas, the preheating of combustion air and gas, and fully closed mixed air valves, other measures, such as using an oxygen-enriched blast stove, burning high heating value converter gas, increasing the number of stove changes to reduce the time needed for stove blasts, were taken to increase the blast temperature of the 2 500 m3 BF in recent years. The blast temperature of the 2 500 m3 BF was continuously increased in these years. The monthly average temperature of the 2 500 m3 BF reached 1 158℃, with the highest blast temperature reaching 1 195 ℃ in 2006. This technique of increased blast temperatures has reached an advanced level in China.
文摘Based on the existing technology and equipment for stainless steel production, the smelting process of ferritic stainless steel in the argon-oxygen decarburization （AOD） furnace using blast furnace （BF）molten iron （after dephosphorization） and ferrochrome alloy is studied and discussed. In the new process,phosphorus and other harmful elements are reduced to a lower level （P≤0. 020% ） when smelting ferritic stainless steel. With this process,both production flexibility and efficiency are enhanced. As no electric furnace is used in the smelting, the production cost is lowered with a great deal of electric power saved, while the total yield of chromium is increased.
基金This study was financially supported by Baosteel, College Natural Science Research Project of Jiangsu Province (No. 04KJB430022,05KJD450043)the National Natural Science Foundation of China (No.50474037)
文摘To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refining ladle slag. The effect of CaO-CaF2 on the melting point, viscosity, and desulfurizing capability of the ladle slag was investigated. The melting point of the unmodified ladle slag is 1439℃. When adding 20wt% CaO-CaF2, the melting point is decreased to 1327℃. At 1500℃. the viscosity of the unmodified ladle slag is 6.5 Pa.s, which can be decreased lower than 2 Pa.s by adding more than 10wt% CaO-CaF2. The experimental results of desulfu- rization of the melts show that the desulfurizing power of the ladle slag can be enhanced by adding CaO-CaF2.
