A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured ...A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. The influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. The results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. The effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.展开更多
Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were inve...Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were investigated using tensile tests, optical microscopy （OM）, and transmission electron microscopy （TEM）. The results show that the ultimate tensile strength and yield strength are improved by 94 and 110 MPa, respectively, and the elongation to failure remains at a reasonable extent （11.1%） in the Al-Zn-Mg-Cu-Zr based alloy with 0.21 wt.% Sc addition after solution heat treatment at 475°C for 40 min and then aged at 120°C for 24 h. The addition of minor Sc induces the formation of Al3（Sc,Zr） particles, which are highly effective in refining the cast microstructures, retarding recrystallization, and pinning dislocations. The increment of strength is attributed mainly to fine grain strengthening, precipitation strengthening of Al3（Sc,Zr） particles, and substructure strengthening.展开更多
Achieving a uniform structure with few defects in heavy steel ingot is of high commercial importance. In this present work, in order to verify the potential of pulsed magneto-oscillation(PMO) applied in the production...Achieving a uniform structure with few defects in heavy steel ingot is of high commercial importance. In this present work, in order to verify the potential of pulsed magneto-oscillation(PMO) applied in the production of heavy ingot, an induction coil was located at the hot top of the steel ingot to develop a novel technique, named hot top pulsed magneto oscillation(HPMO). The influences of HPMO on the solidification structure, macro segregation and compactness of a cylindrical medium carbon steel ingot with the weight of 160 kg were systematically investigated by optical microscope(OM) and laser induced breakdown spectroscopy original position metal analyzer(LIBSOPA-100). The results show that HPMO not only causes significant grain refinement and promotes the occurrence of columnar to equiaxed transition(CET) but also can homogenize the carbon distribution and enhance the compactness of the steel ingot. Therefore, HPMO technique has the potential to be applied in the production of heavy steel ingots on an industrial scale.展开更多
To control the distribution of nonmetallic inclusions in molten developed method, hot-top pulsed magneto-oscillation （HPMO）, steel is of highly commercial importance. A newly was employed to control nonmetallic incl...To control the distribution of nonmetallic inclusions in molten developed method, hot-top pulsed magneto-oscillation （HPMO）, steel is of highly commercial importance. A newly was employed to control nonmetallic inclusions in a medium-carbon steel ingot. The experimental results present that the position of nonmetallic inclusions of spinel （Al-Mg-O） and Mn-S inclusions is significantly influenced by HPMO. The number of nonmetallic inclusions gradually increased from the lateral wall to the center of ingot along the radial direction under the impact of HPMO treatment, whereas this distribution trend cannot be observed in the reference sample without HPMO treatment. In addition, the number of inclusions along vertical direction is proportional to the height of ingot, especially for the inclusions with the size of larger than 10 pro. It indicates that the application of HPMO can push away inclusions from lateral to center, and then the expelled inclusions aggregate and rise up to the top of ingot.展开更多
The solidification of 4.4 t cold work tool steel ingot type X210Crl2 was simulated by Magma software. By the reduction of ingot height, solidification modeling and pouring of a new 3 t ingot were performed and decreas...The solidification of 4.4 t cold work tool steel ingot type X210Crl2 was simulated by Magma software. By the reduction of ingot height, solidification modeling and pouring of a new 3 t ingot were performed and decreasing the porosity formation potential in 3 t ingot in comparison with 4.4 t ingot on the basis of Niyama criterion was ob-served which was in good accordance with experimental data. In order to produce sound ingot, a new 2.8 t ingot mould was designed which includes some parameteric changes in mould such as mould slope, slenderness ratio, mould concavity radius, fillet radius of mould internal corners and feeding diameter to ingot upper diameter ratio. Furthermore, the effects of insulating between kokil and feeding ring and also insulating the outer surface of feeding ring as well as insulating the outer surface of one third of kokil upper part on eenterline porosity formation were in-vestigated in both 2.8 and 4.4 t ingots. The results show that the ingot which was produced in new designed 2.8 t mould has a better Niyama pattern and the centerline porosities were eliminated.展开更多
In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium a...In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium alloy ingots during VAR process.The results show that the temperature fields obtained by the simulation are well validated through the experiment results.The temperature distribution is different during the whole VAR process and the steady-state molten pool forms at 329 s for d100 mm × 180 mm ingots.At the initial stage of remelting,the heat dissipation of crucible bottom plays an important role in the whole heat dissipation system.At the middle of remelting,the crucible wall becomes a major heat dissipation way.The effect of cooling velocity on the solidification structure of ingots was investigated based on the temperature fields and the results can well explain the macrostructure of titanium alloy ingots.展开更多
基金Project(2005L186) supported by Educational Department of Liaoning Province, China
文摘A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. The influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. The results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. The effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.
基金supported by the National High-Tech Research and Development Program of China (No. 2006AA03Z523)
文摘Five kinds of Al-Zn-Mg-Cu-Zr based alloys with different Sc additions were prepared by ingot metallurgy. The effects of minor Sc on the microstructure and mechanical properties of Al-Zn-Mg-Cu-Zr based alloys were investigated using tensile tests, optical microscopy （OM）, and transmission electron microscopy （TEM）. The results show that the ultimate tensile strength and yield strength are improved by 94 and 110 MPa, respectively, and the elongation to failure remains at a reasonable extent （11.1%） in the Al-Zn-Mg-Cu-Zr based alloy with 0.21 wt.% Sc addition after solution heat treatment at 475°C for 40 min and then aged at 120°C for 24 h. The addition of minor Sc induces the formation of Al3（Sc,Zr） particles, which are highly effective in refining the cast microstructures, retarding recrystallization, and pinning dislocations. The increment of strength is attributed mainly to fine grain strengthening, precipitation strengthening of Al3（Sc,Zr） particles, and substructure strengthening.
基金financially supported by the National Natural Science Foundation of China(Granted No.U1760204,51504048)the National Key Research Program of China(Granted No.2017YFB0701800)
文摘Achieving a uniform structure with few defects in heavy steel ingot is of high commercial importance. In this present work, in order to verify the potential of pulsed magneto-oscillation(PMO) applied in the production of heavy ingot, an induction coil was located at the hot top of the steel ingot to develop a novel technique, named hot top pulsed magneto oscillation(HPMO). The influences of HPMO on the solidification structure, macro segregation and compactness of a cylindrical medium carbon steel ingot with the weight of 160 kg were systematically investigated by optical microscope(OM) and laser induced breakdown spectroscopy original position metal analyzer(LIBSOPA-100). The results show that HPMO not only causes significant grain refinement and promotes the occurrence of columnar to equiaxed transition(CET) but also can homogenize the carbon distribution and enhance the compactness of the steel ingot. Therefore, HPMO technique has the potential to be applied in the production of heavy steel ingots on an industrial scale.
基金Acknowledgements The authors acknowledge the financial supports from the National Natural Science Foundation of China （Grant Nos. U1760204 and 51504048）, the National Key Research Program of China （Grant No. 2017YFB0701800） and the Science and Technology Commission of Shanghai Municipality （Grant No. 15520710800）.
文摘To control the distribution of nonmetallic inclusions in molten developed method, hot-top pulsed magneto-oscillation （HPMO）, steel is of highly commercial importance. A newly was employed to control nonmetallic inclusions in a medium-carbon steel ingot. The experimental results present that the position of nonmetallic inclusions of spinel （Al-Mg-O） and Mn-S inclusions is significantly influenced by HPMO. The number of nonmetallic inclusions gradually increased from the lateral wall to the center of ingot along the radial direction under the impact of HPMO treatment, whereas this distribution trend cannot be observed in the reference sample without HPMO treatment. In addition, the number of inclusions along vertical direction is proportional to the height of ingot, especially for the inclusions with the size of larger than 10 pro. It indicates that the application of HPMO can push away inclusions from lateral to center, and then the expelled inclusions aggregate and rise up to the top of ingot.
文摘The solidification of 4.4 t cold work tool steel ingot type X210Crl2 was simulated by Magma software. By the reduction of ingot height, solidification modeling and pouring of a new 3 t ingot were performed and decreasing the porosity formation potential in 3 t ingot in comparison with 4.4 t ingot on the basis of Niyama criterion was ob-served which was in good accordance with experimental data. In order to produce sound ingot, a new 2.8 t ingot mould was designed which includes some parameteric changes in mould such as mould slope, slenderness ratio, mould concavity radius, fillet radius of mould internal corners and feeding diameter to ingot upper diameter ratio. Furthermore, the effects of insulating between kokil and feeding ring and also insulating the outer surface of feeding ring as well as insulating the outer surface of one third of kokil upper part on eenterline porosity formation were in-vestigated in both 2.8 and 4.4 t ingots. The results show that the ingot which was produced in new designed 2.8 t mould has a better Niyama pattern and the centerline porosities were eliminated.
基金Project(2007CB613802) supported by the National Basic Research Program of China
文摘In order to get a better understanding of the vacuum consumable arc remelting(VAR) processes and thus to optimize them,a 3D finite element model was developed for the temperature fields and heat transfer of titanium alloy ingots during VAR process.The results show that the temperature fields obtained by the simulation are well validated through the experiment results.The temperature distribution is different during the whole VAR process and the steady-state molten pool forms at 329 s for d100 mm × 180 mm ingots.At the initial stage of remelting,the heat dissipation of crucible bottom plays an important role in the whole heat dissipation system.At the middle of remelting,the crucible wall becomes a major heat dissipation way.The effect of cooling velocity on the solidification structure of ingots was investigated based on the temperature fields and the results can well explain the macrostructure of titanium alloy ingots.
