6061铝合金半固态浆料的行波电磁搅拌制备工艺

采用低过热度浇注和弱行波电磁搅拌工艺,成功制备出6061铝合金半固态浆料。研究了浇注温度、搅拌功率和搅拌时间对6061铝合金半固态浆料的影响。结果表明:低过热度浇注和弱行波电磁搅拌技术可获得具有良好球状初生α-Al的6061合金半固态组织。浇注温度接近液相线温度,搅拌功率大于2.5kW,搅拌时间大于10s时,6061铝合金半固态浆料中的初生α-Al细小圆整,尺寸均匀。但是当浇注温度降至液相线温度时,组织中出现少量树枝晶。最佳工艺参数:浇注温度667℃、搅拌功率2.5kW、搅拌时间10s。     

合工艺制备半固态A356铝合金浆料的研究

将晶粒细化处理引入低过热度浇注和弱电磁搅拌技术中,形成了制备半固态合金浆料的复合工艺.应用复合工艺制备了半固态A356铝合金浆料,研究了复合工艺对所制备的半固态初生0相形貌和尺寸的影响.研究结果表明,细化处理的液态A356铝合金经低过热度浇注和弱电磁搅拌可制备具有颗粒状和蔷薇状初生α相的半固态浆料,并且浇注温度可适当提高.与未经细化处理的A356铝合金试样相比,细化处理可显著改善A356铝合金中初生α相的晶粒尺寸和颗粒形貌及其沿铸锭径向上的分布.     

行波电磁搅拌制备半固态AlSi7Mg合金浆料

采用低过热度浇注和弱行波电磁搅拌复合制备工艺制备较大容量的半固态AlSi7Mg合金浆料,探讨了电磁搅拌功率和频率对较大容量半固态AlSi7Mg合金浆料组织中的初生α-Al形貌和分布的影响规律。试验结果表明,在低过热度浇注和弱行波电磁搅拌条件下,当浇注温度为630℃、搅拌功率为1.52kW、电磁搅拌频率为5Hz、搅拌时间为8s时,可制备出初生α-Al形貌呈小而圆整的球状晶粒、组织分布均匀、较大容量的半固态AlSi7Mg合金浆料。在低过热度浇注和弱行波电磁搅拌条件下,当浇注温度为630℃、电磁搅拌频率为5Hz,,适当提高电磁搅拌功率可改善初生a-Al的形貌,组织分布比较均匀,但当搅拌功率超过1.52kW时,初生α-Al形貌并没有得到进一步的改善,初生α-Al形貌大部分为球状,组织分布也比较均匀。在低过热度浇注和弱行波电磁搅拌条件下,当浇注温度为630℃、电磁搅拌功率为1.27kW,适当提高电磁搅拌频率可改善初生α-Al的形貌,但当电磁搅拌频率超过10Hz时,初生α-Al形貌并没有得到明显改善,初生α-Al形貌大部分以球状为主,组织分布比较均匀。     

弱搅拌功率对半固态AlSi7Mg合金浆料组织的影响

采用低过热度浇注和弱电磁搅拌制备浆料技术制备半固态AlSi7Mg合金浆料,研究了弱搅拌功率对合金浆料初生相α-Al形貌的影响以及浆料组织的径向分布.研究结果表明, 在低过热度浇注和弱电磁搅拌条件下,当AlSi7Mg合金液在浇注温度为630 ℃、搅拌功率为0.36 kW时可制备出初生α-Al相形貌呈小而圆整的球状晶粒、组织分布均匀、直径为127 mm的AlSi7Mg合金浆料;在低过热度浇注和弱电磁搅拌条件下,适当提高搅拌功率可改善初生α-Al相形貌,但当搅拌功率提高到一定程度,再增大搅拌功率,初生α-Al相形貌并没有得到进一步改善;从半固态AlSi7Mg合金浆料组织的径向分布看,由边部到心部,浆料的组织形貌从枝晶组织向蔷薇状组织再向球状组织演化.     

低过热度浇注弱电磁搅拌对半固态Al-30Si组织的影响

对低过热度浇注弱电磁搅拌制备Al-30Si过共晶合金半固态浆料过程中浇注温度、搅拌功率、搅拌时间等工艺参数与浆料组织间的影响规律进行了研究.结果表明,低过热度浇注弱电磁搅拌技术可以制备较理想的半固态Al-30Si合金浆料.与常规铸造相比,初生Si最小晶粒尺寸由16μm减小到了7μm,最大晶粒尺寸由296μm减小到了23μm,平均晶粒尺寸由138.80μm减小到了11.49μm;初生Si的分布更加均匀,形状更加圆整;浇注温度、搅拌功率和搅拌时间主要影响初生Si形貌、分布和尺寸变化.     

浇注温度和电磁搅拌对半固态6061铝合金组织的影响

应用低过热度浇注和电磁搅拌技术制备了半固态6061铝合金浆料,研究了浇注温度和电磁搅拌对半固态6061铝合金微观组织形貌的影响。结果表明,浇注温度对半固态6061铝合金的凝固组织影响很大,半固态6061合金在660℃下浇注的晶粒最为细小;电磁搅拌可以有效地改善半固态6061铝合金的凝固组织形貌和晶粒尺寸。当电磁频率为30 Hz且搅拌15s时,凝固组织的形貌及尺寸最佳。通过试验获得了制备半固态6061铝合金浆料合适的工艺参数。     

半固态金属浆料先进制备技术的研究进展

总结了10多年来半固态金属浆料先进制备工艺的研究和应用现状,分别介绍了压室浆料、双螺旋机械搅拌浆料、低过热度倾斜板浇注浆料、低过热度浇注和弱机械搅拌浆料、连续流变转换浆料、低过热度浇注和弱电磁搅拌浆料、蛇形通道浇注浆料、熔体分散混合浆料、转桶搅拌浆料、波浪倾斜板浇注浆料、旋转倾斜圆筒浆料、超声振动浆料、倒锥形通道浇注浆料、自孕育浆料、偏旋热焓平衡浆料、气泡搅拌浆料、环状电磁搅拌浆料等金属浆料的先进制备工艺及其发展前景。     

半固态金属浆料制备技术的研究进展

总结了30余年来半固态金属浆料制备技术的研究和应用现状,分别介绍了压室浆料制备技术、单螺旋机械搅拌浆料制备技术、双螺旋机械搅拌浆料制备技术、低过热度倾斜板浇注浆料制备技术、低过热度浇注和弱机械搅拌浆料制备技术、连续流变转换浆料制备技术、低过热度浇注和弱电磁搅拌浆料制备技术、蛇形通道浇注浆料制备技术、熔体分散混合浆料制备技术、转桶搅拌浆料制备技术、波浪倾斜板浇注浆料制备技术、旋转倾斜圆筒浆料制备技术、超声振动浆料制备技术、熔体处理和双向电磁搅拌浆料制备技术、低于液相线温度浆料制备技术、偏旋热焓平衡浆料制备技术、气泡搅拌浆料制备技术及其发展前景。     

半固态A356铝合金流变浆料的制备技术研究

利用行波电磁搅拌和低过热度浇注复合制备工艺成功地制备了A356半固态流变浆料。研究了浇注温度、搅拌功率和搅拌时间对A356铝合金的半固态浆料的影响。研究表明,该工艺可制备出符合流变成形所需的A356铝合金半固态浆料,浇注温度在液相线附近,搅拌功率越大,搅拌时间大于6s制备的A356半固态流变浆料中的初生α-Al越圆整,尺寸越细小。最佳工艺参数:搅拌温度为630℃,搅拌功率为1.2kW,搅拌时间为6s。     

半固态铝合金浆料的复合制备和流变成形研究

利用短时弱电磁搅拌和低过热度浇注制备了半固态AlSi7Mg铝合金浆料,随后对该浆料进行了均热处理,并探讨了浆料温度、压射比压与压射速度对铝合金浆料流变成形过程的影响.制备结果表明,在630～650 ℃下浇注,同时辅以短时低强度电磁搅拌,AlSi7Mg合金中的初生α-Al呈现为球状,个别的初生α-Al呈现为蔷薇状;在固液两相区进行均热处理时,促进了初生α-Al的熟化作用,使初生α-Al进一步球化和粗化.成形结果还表明,浆料温度、压射比压和压射速度对半固态AlSi7Mg合金浆料的充填性影响较大,压射比压和压射速度越大及浆料温度越高,型腔越容易充满;铁芯位置距离内浇道越近,越有利于半固态AlSi7Mg合金浆料的充填;对于试验的钥匙铸件,只要浆料温度≥585 ℃,或压射比压≥20 MPa,或压射速度≥1.73 m/s,半固态AlSi7Mg合金浆料都可充满型腔.流变成形铸件的组织分布很均匀,表明采用低过热度浇注和弱电磁搅拌相结合所制备的半固态AlSi7Mg铝合金浆料适合流变成形,有利于获得高质量的压铸件.     

Effect of pouring temperature on semi-solid slurry of ZL101 alloy prepared by slightly electromagnetic stirring

The semi-solid slurry of ZL101 alloy is prepared by a combination technology of low superheat poudng and slightly electromagnetic stirring. The effects of pouring temperature on the slurry prepared by the technology are investigated. The results indicate that it is feasible to prepare the slurry with globular primary phases by low superheat pouring and slightly electromagnetic stirring, and that the pouring temperature has an important effect on the morphology and the size of primary α-Al in ZL101 alloy. By applying suitable slightly electromagnetic stirring combining with relatively increased pouring temperature, i.e., in a practical way to apply low superheat pouring technology, is capable of obtaining appropriate semi-solid slurry of ZL101 alloy with globular shape of primary phase. Compared with the samples made by low superheat pouring only without stirring, the samples prepared by applying both slightly electromagnetic stirring and low superheat pouring can enable to achieve the same grain size and morphology of the primary phase with that of pouring at 15-35℃ higher.     

Preparation of Semi-Solid AlSi7Mg Alloy Slurry

The semi-solid AlSi7Mg alloy slurry of large size was prepared by the low superheat pouring and weak electromagnetic stirring in this paper. The effects of pouring temperature and stirring power on the microstructure of the AlSi7Mg alloy slurry were studied. The results show that the semi-solid AlSi7Mg alloy slurry of 127mm in diameter can be prepared by the low superheat pouring and weak electromagnetic stirring technology and this new technology can save energy and make the pouring process convenient. When the liquid AlSi7Mg alloy is poured at 650 or 630, the solidified microstructure of the AlSi7Mg alloy slurry prepared by the weak electromagnetic stirring is remarkably improved compared with that of the slurry without stirring, the primary -Al grains appear rosette-like or spherical. When the pouring temperature is decreased, the shape of the primary -Al grains is gradually changed from dendritic-like grains to spherical grains. When the pouring temperature is appropriately increased, namely raised to a certain superheat, the pouring process becomes easier and an ideal spherical microstructure of the AlSi7Mg alloy slurry prepared by the weak electromagnetic stirring can also be obtained, in this experiment, when the stirring power is 0.36kW, the optimized pouring temperature parameter is 630.When the AlSi7Mg alloy slurry is prepared by the low superheat pouring and weak electromagnetic stirring, when the pouring temperature is 630,increasing the stirring power appropriately could gain better spherical primary -Al grains,but if the stirring power is increased to a certain value, the shape of the primary 冄-Al grains is not further improved, in this experiment, the optimized stirring power parameter is 0.36kW.     

Preparation of semi-solid AlSi7Mg alloy slurry with big capability

Semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak traveling-wave electromagnetic stirring.The effects of pouring temperature and stirring power on the microstructure of AlSi7Mg alloy slurry were studied.The results show that the semi-solid AlSi7Mg alloy slurry of 5 kg can be prepared.This new technology can save energy and make the pouring process convenient.When the pouring temperature is decreased at a stirring power of 0.41 kW,the shape of primary α-Al grains gradually changes from dendritic-like to spherical.When the alloy melt is poured at the temperature(630°C) with a certain superheat,the pouring process becomes easier,and the spherical microstructure of AlSi7Mg alloy slurry can be prepared by the weak traveling-wave electromagnetic stirring.When the pouring temperature is 630°C,increasing the stirring power appropriately can result in better spherical primary α-Al grains,but if the stirring power is increased to a certain value(1.72 kW),the shape of primary α-Al grains does not obviously improve when the stirring power is continually increased.     

Manufacture technique of semi-solid slurry of hypoeutectic Al-Si alloy by low superheat pouring and weak electromagnetic stirring

Semi-solid metal (SSM) process is a relatively new technology that offers distinct advantages over other near-net-shape casting processes, such as a more homogeneous microstructure, less porosity and segregation, and improved mechanical properties[1-3]. SSM can be divided into thixoforming and rheoforming, in which rheoforming is usually advantageous from the point of view of an energy and cost saving when compared with thixoforming, so rheoforming has been paid attention again by engineers i…     

Research on semi-solid slurry of a hypoeutectic Al-Si alloy prepared by low superheat pouring and weak electromagnetic stirring

The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouting temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature （or superheat） and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouring temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.     

Effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy

The fractal dimensions of primary phase morphology in semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring were calculated, and the effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy was researched. The results indicate that it is feasible to prepare semisolid A356 alloy slurry by low superheat pouring and slightly electromagnetic stirring, and there is an important effect of pouring temperature on the morphology and the grain size of the primary phase in semi-solid A356 alloy, in which the reduction of pouring temperature can obviously improve grain size and shape factor of primary phase in semi-solid A356 alloy under the condition of a certain stirring power. The primary phase morphology of semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring can be characterized by fractal dimension, and the primary phase morphology obtained by the different processing parameters has the different fractal dimensions. Solidification of semi-solid alloy is a course of change in fractal dimension.     

Effect of Grain-Refined on Primary α Phase in Semi-Solid A356 Alloy Prepared by low superheat Pouring and Slightil Electromagnetic Stirring

The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.     

EFFECT OF GRAIN REFINING ON PRIMARY α PHASE IN SEMI-SOLID A356 ALLOY PREPARED BY LOW SUPERHEAT POURING AND SLIGHT ELECTROMAGNETIC STIRRING

The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.     

Annulus electromagnetic stirring for preparing semisolid A357 aluminum alloy slurry

The effects of pouring temperature and annulus gap width on the microstructure of the semi-solid A357 aluminum alloy slurry prepared by annulus electromagnetic stirring(AEMS) technology were investigated. The results show that low pouring temperature and narrow annulus gap are advantageous to obtaining the small spherical primary α(Al) phase. The lower the pouring temperature is and the smaller the annulus gap width is, the more uniform, the smaller and the more spherical the microstructure is. The microstructures obtained by the ordinary electromagnetic stirring and AEMS were compared. The results indicate that the primary α(Al) particles are globular, small and distribute homogeneously in the slurry obtained by AEMS. But in the slurry obtained by the ordinary electromagnetic stirring, the primary α(Al) particles are small dendrites in the edge of the slurry and they are large and rosette-like or dendritic in the inner of the slurry.