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1.
基于遗传算法的低压铸造铝合金车轮工艺优化 总被引:1,自引:1,他引:0
为解决低压铸造铝合金车轮质量控制难度大的问题,采用遗传算法对工艺参数进行优化.基于铸造数值模拟结果,利用BP人工神经网络建立了铸造工艺参数与质量控制目标缩松缺陷和凝固时间的非线性关系,采用遗传算法实现了铸造工艺参数的优化.以某型低压铸造A356铝合金车轮为例,对浇注温度、上模温度、下模温度、侧模温度、模芯温度5个参数进行优化,得到的最佳工艺组合,可有效控制缩松缺陷和凝固时间.利用数值模拟结果、建立神经网络模型,采用遗传算法优化的方法,获得近似最优解,有助于优化低压铸造工艺. 相似文献
2.
Al–steel composite foams comprise of steel hollow spheres embedded in an aluminum matrix and are processed using a gravity
casting technique. The effect of processing parameters such as casting temperature and cooling rate on the microstructure
and mechanical behavior was studied to establish structure–property relationships. Results show that the amount and composition
of intermetallic phases present in the foam microstructure is directly related to casting temperature and cooling rate. Highest
strength and energy absorption were obtained from Al–steel foams with fast solidification rates that minimize the growth of
intermetallic phases. 相似文献
3.
The effect of die geometry on the microstructure of indirect squeeze cast and gravity die cast 7050 (Al-6.2Zn-2.3Cu-2.3Mg) wrought Al alloy 总被引:1,自引:0,他引:1
The indirect squeeze casting process has been used to cast a 7050 (Al-6.2Zn-2.3Cu-2.3Mg) wrought Al alloy to near-net shape
with excellent die replication. Defects which occur with gravity casting, in particular (1) shrinkage pipe, (2) macro-porosity
and (3) hot-tearing, are largely removed by squeeze casting, although regions of macro-porosity can re-appear when thick sections
are fed through substantially thinner sections. Squeeze casting results in a considerable refinement of microstructure compared
to gravity casting due to a marked decrease in solidification time. The decrease in solidification time is caused by intimate
contact between the pressurised melt and the die, which leads to an increase in the heat transfer coefficient. Decreasing
the section thickness also results in a refinement of the microstructure due to a reduction in solidification time.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
4.
多孔铝合金的铸造工艺研究 总被引:6,自引:0,他引:6
采用加压铸造工艺,制备出了多孔铝合金。系统地研究了预制块的制备工艺过程及影响因素。利用所制备的预制块,研究了多孔铝合金的加压铸造工艺。研究表明,预制块孔隙大小及其初始温度、金属液浇注温度、外加压力等影响了金属液在预制块中的充型长度。采用合理的工艺,就可以获得大尺寸的多孔制品。 相似文献
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Hong-Yang Zhao Dong-Ying Ju Takeshi Asakami Lin Hu 《Materials and Manufacturing Processes》2001,16(5):643-654
Experimental studies on the twin roll casting process in order to produce thin aluminum alloy strips are presented in this paper. A new twin roll caster was developed as an effective experimental tool. The caster is equipped with a complete casting system incorporating a control and measuring system using multiple sensors and various actuators. The data acquisition system of the caster can measure various process parameters including meniscus, casting speed, and temperature as well as roll gap and pressure. With this system, aluminum alloy thin strips were manufactured and the process parameters such as strip temperature, casting velocity, and pressing force of roll were investigated. Furthermore, the crystallizability, microstructure, and mechanical properties of the strip are evaluated by X-ray diffractometer, scanning electron microscope, and tensile test. The results revealed the ability of the twin roll caster to produce directly the thin strip of aluminum alloy with improved mechanical strength. 相似文献
7.
《材料科学技术学报》2016,(6)
For the two-step foaming method,one of the most cost-effective ways to fabricate three-dimensional shaped aluminum alloy foams with dense outer surface skin,it is crucial to describe and predict the moldfilling behavior of the shaped aluminum alloy foams with a favorable pore-distribution accurately.In this paper,a mold-filling model for semi-solid aluminum alloy foams was initially established and subsequently employed to predict the filling height,which represents the mold-filling ability of semi-solid aluminum alloy foams in a specially designed tube-like mold.Our results indicate that the proposed model can be applied to characterize the mold-filling property of aluminum alloy melts in a quantitative manner.Theoretically,our findings actually provide a guideline for mass-production of the shaped aluminum alloy foams by using the two-step foaming process. 相似文献
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10.
EPS bead fusion effects on fold defect formation in lost foam casting of aluminum alloys 总被引:1,自引:0,他引:1
The effects of bead fusion in the polymer pattern on fold defect formation in castings produced by the lost foam process have
been investigated. Castings of aluminum alloy 319.1 were produced with commercial patterns that were molded with varying levels
of bead fusion. Each casting was broken into over 40 pieces to identify the fold defect on the fracture surface. The results
indicate that castings produced with patterns with high bead fusion exhibit a greater number and a larger area of folds than
parts obtained by using foams with low bead fusion. 相似文献
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Technique of Aluminum Alloy Composite by Inversion Casting 总被引:5,自引:0,他引:5
The influence of the temperature of liquid aluminum alloy,the dipping time in liquid alloy and the thickness of base strips on the solidified layer was studied during the process of producing aluminum alloy composite strips used in automobile radizator with inversion casting.It is concluded that there is welding as well as diffusion of alloying elements between the base strip and the coating.Experiments proved that the interface has a good bonding. 相似文献
13.
Characterization of close-celled cellular aluminum alloys 总被引:4,自引:0,他引:4
The deformation behaviour of two different types of aluminium alloy foam are studied under tension, compression, shear and hydrostatic pressure. Foams having closed cells are processed via batch casting, whereas foams with semi-open cells are processed by negative pressure infiltration. The influence of relative foam density, cell structure and cell orientation on the stiffness and strength of foams is studied; the deformation mechanisms are analysed by using video imaging and SEM (scanning electronic microscope). The measured dependence of stiffness and strength upon relative foam density are compared with analytical predictions. The measured stress versus strain curves along different loading paths are compared with predictions from a phenomenological constitutive model. It is found that the deformations of both types of foams are dominated by cell wall bending, attributed to various process induced imperfections in the cellualr structure. The closed cell foam is found to be isotropic, whereas the semi-open cell foam shows strong anisotropy. 相似文献
14.
Renguo Guan) Liqing Chen) Jiangping Li) Fuxing Wang) ) School of Materials Metallurgy Northeastern University - Wenhua Road Shenyang China ) The State Key Laboratory of Rolling Automation China 《材料科学技术学报》2009,25(3):395-400
In this paper, a novel near-net-shape forming process, continuous semisolid extrusion process (CSEP) of AZ31alloy was proposed, and the dynamical solidification behaviors and metal flow during the process were firstly investigated.During casting AZ31 alloy by this process, non-uniform microstructure distributions and nonequilibrium solidification region near the roll surface were found in the roll-shoe gap.Microstructural evolution from dendrite to rosette and spherical grains was observed during the casting by CSEP.Casting temperature,roll-shoe gap width and cooling ability have great effect on casting process and metal flow, so these factors should be carefully controlled, a proper casting temperature of 710-750℃ is suggested.The white a phases were strongly stretched during the processing, and the remnant liquids are correspondingly distributes along the solid phase boundaries and also show stripped lines. 相似文献
15.
《Materials Science & Technology》2013,29(6):706-712
AbstractA novel testing machine for a continuous semisolid extending extrusion process (CSEP) has been designed and used to produce AA2017 alloy flat bar. Fine and homogeneous grains of AA2017 slurries with rosette structures were obtained at suitable casting temperatures. During preparation of semisolid AA2017 alloy by the proposed process, rosette grain formation was observed during the application of the large force provided by the rough roll. By controlling casting temperature, AA2017 products were produced with fine surfaces and rectangular transections of 14 × 25 mm. A casting temperature range of 710–750°C was suggested. The microstructure of the product is fine and even with striped appearance and is composed mainly of θ and α phases. The fracture strength of AA2017 product produced by the semisolid extending extrusion process is improved by 100 MPa, and elongation by 29%. 相似文献
16.
The dependence of damping property of fly ash reinforced closed-cell aluminum alloy foams on strain amplitude 总被引:2,自引:0,他引:2
Closed-cell aluminum alloy foams with 1.5, 3.0 wt.% fly ash particles have been manufactured by molten body transitional foaming process. The room temperature damping properties of fly ash reinforced aluminum alloy foams were measured at different strain amplitude in two directions using the forced vibration mode. The results show that the damping properties of fly ash reinforced aluminum alloy foams increase with FA content. A critical strain amplitude εcrit was observed and εcrit decreases with increasing FA content. Moreover, the damping property in the transverse direction is higher than that in the longitudinal direction. The related mechanism has been discussed. 相似文献
17.
为防止某大型复杂铸件产生缩孔缺陷并降低铸造成本,采用数值模拟方法对其铸造工艺参数进行定量化设计.应用Pro CAST软件对铸件进行凝固分析,通过提取凝固结果中的各参数(温度场、固相温度的密度、焓变化等)对模数进行求解,定量得到铸件的高模数分布区域,而后通过分析模数分布区域并结合均衡凝固理论设计了冒口、冷铁与浇注系统,运用Pro CAST软件对铸件的充型及凝固过程进行模拟.研究表明:该大型铸件应采用底注式浇注系统为宜,对铸件中部与底部模数达到2.5 cm的热节处采用冷铁和铬铁矿砂处理热节,对铸件顶部模数达到2.5 cm的部位采用飞边冒口进行补缩;提取凝固模拟结果中热节处的平均模数和金属液体积,即可对冒口尺寸进行定量化设计;通过观察模拟结果中浇口杯金属液水平高度的变化,可得出浇注系统进行液态补缩的时段. 相似文献
18.
铝(镁)合金消失模铸造近净成形技术研究进展 总被引:2,自引:0,他引:2
阐述了铝(镁)合金消失模铸造技术的研究现状,着重介绍了铝(镁)合金消失模铸造在金属液充型、振动凝固、压力凝固以及消失模壳型铸造等技术方面的最新研究进展。研究表明,铝(镁)合金在消失模铸造过程中,需重点解决针孔、缩松等缺陷,提高液态合金的充型能力和铸件的力学性能;通过采用振动凝固和压力凝固的手段,可以提高金属液充型能力、细化组织、提高组织致密性,明显提高铸件力学性能。真空低压消失模壳型铸造技术,可以解决普通消失模铸造易于出现的孔洞和夹杂等缺陷以及浇不足和浇注温度高等问题,是一种生产复杂薄壁高质量铝、镁合金精密铸件的新方法。 相似文献
19.
This article presents an account of experiments used to produce aluminium alloy foams by the melt route process using titanium hydride as a foaming agent. Powdered titanium hydride with content of 0.4–1.4% (mass fraction) was added to the molten pure aluminium and the foaming condition was controlled at 690°C (1274°F). In the process, homogeneous aluminium foams were produced with a calcium amount of 1.0–3.0% (mass fraction). The mechanical properties of the aluminium foams with diverse relative density were tested. The result indicates that the foaming agent is suitable for making small aperture aluminium foams with an average pore diameter of 1.2?mm. 相似文献