To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,th...To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,the positioning of final electromagnetic stirring(F-EMS)was determined by nail-shooting method.Furthermore,the effect of mold electromagnetic stirring(M-EMS)on the macrostructure and internal defects in the round billets was investigated to find out the optimal operating parameters for continuous casting of SWRH 82B round billets.The results show the desirable positioning of F-EMS locates 9.7m below the mold level where the molten steel can be effectively driven by electromagnetic force and disperse central composition segregation.The shrinkage cavity is totally eliminated with the rotational M-EMS.The ratio and index of central composition segregation and center porosity can be reduced significantly. Furthermore,the equiaxed crystal ratio is considerably increased to 64%under 480A/3Hz M-EMS and 500A/10Hz F-EMS. Fine microstructure and mechanical property of wire rod are presented after optimization of combined electromagnetic stirring.Accordingly,the probability of occurrence of cup-cone fracture of wire rod is reduced dramatically.展开更多
The effect of electromagnetic stirring(EMS)on the distribution of Nb particles in solidified microstructure of a Cu-5wt%Nb alloy were studied.In this paper,we have Cu-5wt%Nb alloy remelted and solidified with or witho...The effect of electromagnetic stirring(EMS)on the distribution of Nb particles in solidified microstructure of a Cu-5wt%Nb alloy were studied.In this paper,we have Cu-5wt%Nb alloy remelted and solidified with or without electromagnetic stirring,to study the effect of EMS on the distribution of Nb phase and the hardness of ingots.The 300A/16Hz EMS has refined the mircostrucrure of Cu-5%Nb alloy,with smaller particles sizes and larger amounts,and is benefit to the homogenous distribution of particles.The fitted lognormal distribution of particles diameter that in case without or with EMS are compared,and the EMS case has the highest frequency percentage in the range of smaller size. EMS considerably increased the hardness of Cu-5%Nb alloy ingot.展开更多
In order to reasonably control the free surface oscillations,by using GalnSn low-melting alloy,the fluctuation and distortion behaviour of metal free surface is investigated under AC magnetic field.By simultaneously s...In order to reasonably control the free surface oscillations,by using GalnSn low-melting alloy,the fluctuation and distortion behaviour of metal free surface is investigated under AC magnetic field.By simultaneously superposing DC magnetic field,the damping effect of DC magnetic field on free surface fluctuation is also investigated.In the cylindrical pool,the azimuthal and radial oscillation mode can be found simultaneously due to AC magnetic field. Moreover,the free surface is more stable in square pool than that in the cylindrical pool.Increase coil AC current,the free surface fluctuation is aggravated.A series of surface waves can be observed on free surface with compound magnetic field.Reasonable DC magnetic field can effectively damp the oscillations on the free surface in cylindrical pool.However. the DC magnetic field cannot effectively damp the surface oscillations in square pool.The DC magnetic field has no significant damping effect on the oscillations induced by the lower frequency magnetic force.展开更多
基金Item Sponsored by National Natural Science Foundation of China[No.50834009]the National Natural Science Foundation of China[No.51004038]+1 种基金Key Grant Project of China Ministry of Education(No.311014)the 111 Project of China(No.B07015)
文摘To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,the positioning of final electromagnetic stirring(F-EMS)was determined by nail-shooting method.Furthermore,the effect of mold electromagnetic stirring(M-EMS)on the macrostructure and internal defects in the round billets was investigated to find out the optimal operating parameters for continuous casting of SWRH 82B round billets.The results show the desirable positioning of F-EMS locates 9.7m below the mold level where the molten steel can be effectively driven by electromagnetic force and disperse central composition segregation.The shrinkage cavity is totally eliminated with the rotational M-EMS.The ratio and index of central composition segregation and center porosity can be reduced significantly. Furthermore,the equiaxed crystal ratio is considerably increased to 64%under 480A/3Hz M-EMS and 500A/10Hz F-EMS. Fine microstructure and mechanical property of wire rod are presented after optimization of combined electromagnetic stirring.Accordingly,the probability of occurrence of cup-cone fracture of wire rod is reduced dramatically.
基金Item Sponsored by the National Natural Science Foundation of China[No.50901019]the Fundamental Research Funds for the Central Universities[No.N100409009]+4 种基金the Wuhan National High Magnetic Field Center[No.WHMFCKF2011007]China Postdoctoral Science Foundation[No.20100471458]the National Natural Science Foundation of China[No.51004038]National High-tech R&D Program of China[No.2007AA03Z519]the 111 Project of China(No.B07015)
文摘The effect of electromagnetic stirring(EMS)on the distribution of Nb particles in solidified microstructure of a Cu-5wt%Nb alloy were studied.In this paper,we have Cu-5wt%Nb alloy remelted and solidified with or without electromagnetic stirring,to study the effect of EMS on the distribution of Nb phase and the hardness of ingots.The 300A/16Hz EMS has refined the mircostrucrure of Cu-5%Nb alloy,with smaller particles sizes and larger amounts,and is benefit to the homogenous distribution of particles.The fitted lognormal distribution of particles diameter that in case without or with EMS are compared,and the EMS case has the highest frequency percentage in the range of smaller size. EMS considerably increased the hardness of Cu-5%Nb alloy ingot.
基金Item Sponsored by National Natural Science Foundation of China[No.50834010 and 50834009]Natural Science Foundation of Liaoning Province[20102074]the Fundamental Research Funds for the Central Universities of China[N100409005]
文摘In order to reasonably control the free surface oscillations,by using GalnSn low-melting alloy,the fluctuation and distortion behaviour of metal free surface is investigated under AC magnetic field.By simultaneously superposing DC magnetic field,the damping effect of DC magnetic field on free surface fluctuation is also investigated.In the cylindrical pool,the azimuthal and radial oscillation mode can be found simultaneously due to AC magnetic field. Moreover,the free surface is more stable in square pool than that in the cylindrical pool.Increase coil AC current,the free surface fluctuation is aggravated.A series of surface waves can be observed on free surface with compound magnetic field.Reasonable DC magnetic field can effectively damp the oscillations on the free surface in cylindrical pool.However. the DC magnetic field cannot effectively damp the surface oscillations in square pool.The DC magnetic field has no significant damping effect on the oscillations induced by the lower frequency magnetic force.
