流变压铸YL112铝合金的组织和力学性能

利用自主研发的剪切低温浇注式流变制浆工艺(LSPSF)制备浆料,在DCC280卧式压铸机上进行半固态压铸成形试验,研究了流变压铸YL112铝合金的组织和力学性能.试验结果表明,在浇注温度为620℃、输送管转速为90 r/min、结晶器预热温度为550℃、倾斜角为25°的工艺参数下得到的压铸件经过测试,压铸缺陷较少,力学性能优良,热处理后性能进一步提高.     

锥桶式流变成形机制备A356铝合金半固态浆料的研究

采用自主研发的锥桶式流变成形机(TBR),研究了浇注温度、内锥桶转速及剪切温度对A356铝合金半固态组织的影响规律。结果表明,适当降低浇注温度、提高内锥桶转速或降低剪切温度,均有利于获得初生相颗粒细小、圆整、分布均匀的半固态组织;当浇注温度为660℃、内锥桶转速为500r/min、剪切温度为590℃时,获得了理想的半固态浆料,其初生固相颗粒平均直径为41μm,形状因子为0.89;半固态组织的形成受到枝晶破碎和枝晶抑制生长两方面因素的共同影响。     

浇注温度和ECAP对铝合金坯料组织的影响

采用近液相线法结合新SIMA法复合工艺制备半固态A356铝合金坯料,研究了浇注温度、等径角挤压（ECAP）和半固态处理温度、时间对坯料组织的影响。结果表明,适当的工艺参数可以制备出球状初生α—Al相晶粒的半固态A356铝合金坯料,其中较合理的工艺参数为：近液相线浇注温度为610℃,半固态保温温度为580℃,半固态保温时间为20min。     

Y对A356铝合金半固态初生相形貌的影响

利用低过冷度浇注工艺制备了A356铝合金半固态浆料,研究了稀土Y对合金半固态初生相形貌的影响。采用正交设计方法,优化了A356铝合金半固态初生相形貌的影响因素,通过直观分析与方差分析表明,经稀土Y变质处理及低过冷度浇注获得A356半固态初生球晶的最佳工艺条件:浇注温度为595℃,保温时间为3min,Y的加入量为0.5%。此时其晶粒在铸态下的形状因子为0.7,等积圆直径为49.6μm,其中浇注温度是晶粒形貌和尺寸的最主要影响因素,可信度达到95%;其次是Y的加入量和保温时间。     

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。     

蛇形通道浇注流变压铸铝合金拉伸试样的力学性能和微观组织(英文)

开发出一种新颖的A356铝合金半固态加工技术——蛇形通道浇注流变压铸技术(SCRC)。采用SCRC技术制备A356铝合金拉伸试样,并研究试样在铸态和T6热处理条件下的力学性能和微观组织。结果表明:在铸态下拉伸试样的抗拉强度可达到250MPa左右,伸长率在8.6%-13.2%;经过T6热处理后,抗拉强度可提高约30%,但伸长率略有下降。在这些实验条件下,蛇形通道浇注技术可制备出初生α1(Al)的形状因子为0.78-0.89和晶粒尺寸为35-45μm的优质半固态A356铝合金浆料。与传统压铸工艺相比,SCRC技术可改善拉伸试样的微观组织并提高它的力学性能。这种SCRC技术具有与传统压铸设备衔接简便、取消了半固态浆料的保存及输送步骤和具有较高的性价比等优点。     

螺旋线槽制备A356铝合金半固态浆料

研究了螺旋线槽的螺旋角度和试验浇注温度对螺旋线槽工艺制备A356铝合金半固态浆料组织的影响。结果表明,合金熔体的浇注温度和螺旋线槽螺旋角度影响A356铝合金熔体的冷却效果和自搅拌混合程度。在其他线槽结构参数和工艺参数一定的情况下,A356铝合金熔体合理的浇注温度,匹配一定的螺旋线螺旋角度,可以制备出合格的半固态浆料。     

流变压铸工艺参数对过共晶Al-30%Si合金显微组织和力学性能的影响（英文）

研究流变压铸工艺参数浇注温度、振动频率和蛇形通道弯道数量对Al-30%Si合金的显微组织和力学性能的影响。流变压铸过程中的半固态Al-30%Si合金浆料采用振动蛇形通道浇注工艺制备。实验结果表明:浇注温度、振动频率和通道数量对Al-30%Si合金显微组织和力学性能的影响较大。在浇注温度为850°C、通道弯道数量为12和振动频率为80 Hz的条件下,流变压铸工艺制备的样品组织的初生硅晶粒被细化成平均粒径约为24.6μm的块状颗粒;此外,流变压铸样品的抗拉强度、伸长率和硬度分别为296 MPa、0.87%和HB 155。因此,振动蛇形通道浇注工艺能有效地细化组织中的初生Si晶粒。初生Si晶粒的细化是流变压铸样品力学性能改善的主要原因。     

铝合金半固态浆料LSPSF法在线制备

利用自主开发的剪切低温浇注式半固态浆料制备 (LSPSF) 工艺装置,研究了不同浇注温度和输送管转速对A356、A380铝合金半固态浆料组织的影响.结果表明,在输送管倾角为20°、浆料蓄积器温度为500 ℃、转管转速为90～150 r/min、浇注温度在液相线以上(30±10) ℃时,可以获得良好的近球形半固态浆料微观组织.经过实际试生产,证明LSPSF工艺效率高、性能稳定,可以实现铝合金半固态浆料的在线制备.     

蛇形通道制备半固态铝合金浆料的研究

试验研究了蛇形通道的弯道数量和浇注温度对蛇形通道浇注制备半固态A356铝合金浆料组织的影响.结果表明,用蛇形通道浇注制备半固态A356 铝合金浆料时,蛇形通道的弯道数量越多,制备出的浆料组织就越理想,但是弯道数量的增多又容易造成通道的堵塞;当弯道数量为1～3个时,均可得到理想的球状半固态A356 铝合金浆料.采用蛇形通道浇注制备半固态A356 铝合金浆料时,随着浇注温度的降低,制备出的浆料组织越来越好;当浇注温度为640～680 ℃时,均可得到理想的球状半固态A356 铝合金浆料.     

Preparation of semi-solid slurry containing fine and globular particles for wrought aluminum alloy 2024

The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouting with shearing field（LSPSF）. The appreciate combination of pouring temperature and rotation speed of barrel, can give rise to a transition of the growth morphology of primary a（Al） from coarse-dendritic to coarse-particle-like and further to fine-globular. The combined effects of both localized rapid cooling and vigorous mixing during the initial stage of solidification can enhance wall nucleation and nuclei survival, which leads to the formation of fine-globular primary a（Al）. By using semi-solid slurry prepared by LSPSF, direct squeeze cast cup-shaped component with improved mechanical properties such as yield strength of 198 MPa, ultimate tensile strength of 306 MPa and elongation of 10.4%, can be obtained.     

Taper barrel rheomoulding process for semi-solid slurry preparation and microstructure evolution of A356 aluminum alloy

The self-developed taper barrel rheomoulding (TBR) machine for light alloy semi-solid slurry preparation was introduced. The semi-solid slurry was obtained from the intense shearing turbulence of the alloy melt in the cause of solidification, which was further caused by the relative rotation of the internal and external taper barrel whose surface contained wale and groove. The heat transmission model of TBR process, the flow rules and the shearing model of the alloy melt were deduced. Taking A365 as experimental material, the microstructure evolution rules under different slurry preparation processes were analyzed. The results show that decreasing the pouring temperature of A365 alloy melt properly or increasing the shearing rate helps to obtain ideal semi-solid microstructure with the primary particle size of about 70 μm and the shape factor of above 0.8.     

Experimental and CFD investigation on the solidification process in a co-rotating twin screw melt conditioner

Twin screw melt conditioners are used for mixing purposes and are mainly used for polymer processing. These conditioners (extruders) can be used for liquid metal processing in which liquid metal/slurry is subjected to high shear stress. This process results in grain refinement of structure. In this article, in a co-rotating twin screw melt conditioner, the solidification process of a liquid along with temperature variations of the melt with regard to the complexity of the flow has been examined. With the aid of dynamic mesh scheme, a Computational Fluid Dynamic (CFD) simulation was performed. The achieved results were in good agreement with values based on the experimental measurements. It was concluded that shearing and pouring temperatures play important roles in solidification progression and the main reason of surviving nuclei is heat dissipation from the barrel. Also, the main factor affecting the grain size is the temperature differences between the pouring and the setting temperature. It was observed that, the twin screw melt conditioner can decrease the temperature gradient and with the help of turbulence, providing appropriate conditions for formation of fine and equiaxed grains.     

挤压铸造半固态A356铝合金的组织与力学性能

采用低温铸造方法制备A356铝合金半固态坯料.在200 t立式油压机上用挤压铸造方法将A356铝合金半固态浆料挤压成件.研究挤压铸造件的微观组织、力学性能,并与液态挤压铸造件进行比较.结果表明,A356铝合金半固态挤压铸造件组织由球形及椭圆形α-Al晶粒和α+Si共晶成分组成,且制件充型完整、无宏观缩孔、组织致密.在比压48.7 MPa,浇注温度575℃,保压时间3s条件下成形的半固态挤压铸造件的抗拉强度、屈服强度、伸长率分别达到278 MPa、225 MPa、13.2％,相比于在比压48.7 MPa,保压时间3s,710℃液态挤压铸造件性能分别提高了8.6％、8.2％、24.5％.A356铝合金半固态挤压铸造成形件具有较高的综合力学性能.     

Effects of processing parameters on microstructure of semi-solid magnesium alloy

In this paper, the effects of pouring temperature of magnesium melt, preheating temperature of the barrel of the screw mixer, and shear rate on the solidified microstructures of semi-solid slurry were investigated by a mechanical stirring semi-solid process. The appropriate processing parameters of slurry preparation were obtained, and the mold filling ability of semi-solid slurry for thin-walled casting was examined. Results indicate that the solid volume fraction of non-dendritic microstructure increases with a decrease in pouring temperature of magnesium melt and the barrel preheating temperature of the screw mixer. Also the grain size of primary α-phase is reduced. Furthermore, the solid volume fraction of semi-solid nondendritic structure decreases with an increase of shear rate. The fine and round granular microstructure with 30～50 μm in size of semi-solid AZ91D magnesium alloy was presented. Finally, a 1.0 mm thin-walled casting with a clear contour and good soundness was successfully made by semi-solid rheo-diecasting.     

Optimization of processing parameters for rheo-casting AZ91D magnesium alloy

A design of experiment technique was used to optimize the microstructure of the AZ91D alloy produced by rheo-casting. The experimental design consists of four parameters(pouring temperature,shearing temperature,shearing time and shearing rate) with three levels.The grain size and shape factor measurements of primaryα-Mg particles were conducted to determine the microstructure.The contribution of each parameter shows that pouring temperature is the most significant parameter affecting the grain size,and t...     

Interface of components with large ratio of altitude to diameter formed by laminated pouring and accumulated liquid forging technology

1　INTRODUCTIONLiquidforgingtechnologywasdevelopedintheFormerSovietUnionin 1937[1] .Fromthenon ,thistechnologyhasbeenappliedintoformingmetalcom ponentsinthefieldsofmilitaryindustryinsomede velopedcountries ,whichbenefitshighlyandshowsstrongvitality .Liquidforgingisakindoftechnologyinwhichmechanicalpressureisappliedwhiletheliq uidmetalispouredintodiecavityandcomponentscanbeobtainedbysolidificationandplasticdeforma tion[13] .Mechanicalpropertiesofliquidforgingcom ponentshavealmostapproache…     

5083合金挤压铸造工艺的研究

以5083合金为原材料进行挤压铸造工艺试验.采用正交试验和极差分析法确定了最佳工艺条件--比压为125MPa,浇注温度为670℃,保压时间为15s.对该工艺条件下试样的微观组织和力学性能进行了分析.结果表明,与普通铸造成形制件相比,挤压铸造成形制件微观组织更加细小、均匀,综合力学性能显著提高,达到或者接近了原热模锻工艺水平.     

Influences of pouring temperature and cooling rate on microstructure and mechanical properties of casting A1-Si-Cu aluminum alloy

This paper investigated the influences of pouring temperature and cooling rate on the microstructure development and mechanical properties for casting Al-Si-Cu aluminum alloy.The microstructure of the as-cast samples was characterized by an optical microscope.The results showed that the dendrite arm spacing(DAS,λ) is well refined by pouring at a higher temperature.The λ decreases with increasing pouring temperature due to the multiplication of the nucleation sites in the superheating liquid melt,and the mechanical properties,such as microhardness and ultimate tensile strength increase correspondingly,while the elongation decreases.The relationships between microhardness and λ for the samples cooled in metal mould and sand mould,are given as HV=118.9 1.246λ and HV=115.2 1.029λ,respectively.The effects of the cooling rate controlled by using permanent mould casting and sand mould casing processes(the cooling medium is air and sand,respectively) on the dendrite arm spacing and mechanical properties are similar to the effect of the pouring temperature.