A double control forming technology combining die casting and forging for the production of Mg alloy components with enhanced properties

A double control forming technology combining the die casting and forging was firstly proposed for the production of Mg alloy components with enhanced properties. In this technology, high-speed filling of liquid melt and high-pressure forging of partially solidified melt were performed by using injection and forging systems of a double control forming device. Some Mg alloy motorcycle wheel components were produced by die casting and double control forming to verify the improvement of the mechanical properties of components formed by double control forming. The results showed that double control forming was an alternative technology for producing the complex Mg alloy components with enhanced properties. Average tensile strength and elongation of Mg alloy components produced by double control forming were greatly improved in comparison with die casting. The average tensile strength was enhanced from 126.8 MPa to 213 MPa and elongation was improved from 3.5% to 7.2%. The optimal process parameters were obtained according to the results of orthogonal experiments, which involved pouring temperature of 675 °C, injection speed of 2 m/s and die temperature of 210 °C. The improved nucleation frequency in the melt caused by the forging pressure led to successful grain refinement of the microstructure of the component produced by double control forming. The defects were removed from the microstructure due to plastic deformation caused by the forging pressure. A refined and densified microstructure led to an enhancement of mechanical properties of Mg alloy component produced by double control forming.     

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.     

Effect of pressure on microstructures and mechanical properties of Al-Cu-based alloy prepared by squeeze casting

A new high-strength aluminum alloy with better fluidity than that of ZL205A was developed. The effect of applied pressure during squeeze casting on microstructures and properties of the alloy was studied. The results show that the fluidity of the alloy is 16% and 21% higher than that of ZL205A at the pouring temperature of 993 K and 1 013 K, respectively. Compared with permanent-mold casting, mechanical properties of the alloy prepared by squeeze casting are much higher. The tensile strength and elongation of the alloy are 520 MPa and 7.9% in squeeze casting under an applied pressure of 75 MPa, followed by solution treatment at 763 K for 1 h and at 773 K for 8 h, quenching in water at normal temperature and aging at 463 K for 5 h. The improvement of mechanical properties is attributed to the remarkable decreasing of the secondary dendrite arm spacing(SDAS) and eliminating of micro-porosity in the alloy caused by applied pressure.     

Influence of technical parameters on strength and ductility of AlSi9Cu3 alloys in squeeze casting

An orthogonal test was conducted to investigate the influence of technical parameters of squeeze casting on the strength and ductility of AlSi9Cu3 alloys. The experimental results showed that when the forming pressure was higher than 65 MPa, the strength (σ_b) of AlSi9Cu3 alloys decreased with the forming pressure and pouring temperature increasing, whereas σ_b increased with the increase of filling velocity and mould preheating temperature. The ductility (δ) by alloy was improved by increasing the forming pressure and filling velocity, but decreased with pouring temperature increasing. When the mould preheating temperature increased, the ductility increased first, and then decreased. Under the optimized parameters of pouring temperature 730 °C, forming pressure 75 MPa, filling velocity 0.50 m/s, and mould preheating temperature 220 °C, the tensile strength, elongation, and hardness of AlSi9Cu3 alloys obtained in squeeze casting were improved by 16.7%, 9.1%, and 10.1%, respectively, as compared with those of sand castings.     

工艺参数对AM50A镁合金双控成形件组织和性能的影响(英文)

利用四因素四水平正交实验研究工艺参数对双控成形AM50A镁合金构件的力学性能和微观组织的影响。双控成形的参数变化曲线表明,锻造过程是在压射过程完成35 ms后启动的。这表明双控成形过程既包含高速充填过程又具有高压密实过程。与压铸相比,双控成形构件既具有好的表面质量又具有高的力学性能。这主要是由于双控成形构件具有细小、均匀且具有很少(或者没有)铸造缺陷的微观组织所致。与浇注温度、模具温度和锻造压力相比,压铸速度对构件的屈服强度、抗拉强度和伸长率有更大的影响。但是与压射速度、模具温度和锻造压力相比,浇注温度对构件的硬度有更大的影响。除模具温度之外,675°C的浇注温度、2.7 m/s的压射速度和4000kN的锻造压力是获得最高的屈服强度、抗拉强度、伸长率和硬度的工艺参数。而要获得最高的屈服强度、抗拉强度、伸长率和硬度的模具温度匹配顺序为:205、195、195和225°C。在压铸件的拉伸断口表面能够发现明显的显微缩松和微裂纹。双控成形构件的拉伸断口表面存在大量的韧窝,没有铸造缺陷。这种韧窝形貌的断口对于提高构件的力学性能非常有利。     

The Effect of Trace Elements on the Cooling Curves,Microstructure and Mechanical Properties of Eutectic Aluminium-Silicon Alloy

Abstract

The effect of trace elements, used for modification, on the cooling curves obtained during solidification, microstructure and mechanical properties of eutectic aluminium-silicon alloy was investigated. The results of this study indicate the following: 1 The addition of sodium or sodium plus strontium or antimony modifies the eutectic silicon while the addition of sulphur does not alter the microstructure.

2 Those elements which modify the eutectic-silicon, lower the eutectic solidification temperature, while those elements which do not bring about modification, do not alter the eutectic solidification temperature.

3 The addition of those elements which modify the eutectic aluminium-silicon alloy, viz., sodium or sodium plus strontium or antimony improves the UTS and percentage elongation. The addition of titanium to eutectic aluminium-silicon alloy containing these trace elements improves the UTS and percentage elongation to a further extent. Among the various trace elements added to eutectic aluminium-silicon alloy, the addition of sodium plus titanium improves the UTS and percentage elongation to the maximum extent.

     

不同压力对挤压铸造Al-Cu-Mg合金性能的影响

使用挤压铸造工艺制备了高强、高韧Al-4.5Cu-1Mg合金。在挤压力为70MPa下成型后,合金的最大抗拉强度达到288.8MPa、伸长率达到12.8%、HRB硬度达到48.3。通过对该合金力学性能及其显微组织的研究表明,合金的抗拉强度、伸长率以及硬度随着压力的增加而增大,并且在70MPa时达到最大值,70MPa之后继续增加压力,对材料性能影响不大。研究了挤压力对合金的密度和导电性的影响。试验结果表明,合金的密度随着压力的增加而快速增大,在挤压压力为70MPa时达到最大值,然后变化不大。     

The effect of casting temperature on the properties of squeeze cast aluminium and zinc alloys

Gravity casting and squeeze casting were carried out on an aluminium alloy with 13.5% silicon and a zinc alloy with 4.6% aluminium with different temperatures, 660, 690 and 720 °C for the former and 440, 460 and 480 °C for the latter. A top-loading crucible furnace was used to melt the alloys. The die-preheat temperatures used were 200–220 °C for the aluminium alloy and 150–165 °C for the zinc alloy. A K-type thermocouples with digital indicator were used to measure the die surface temperature and the molten metal temperature; while a 25 t hydraulic press with a die-set containing a steel mould was used to perform the squeeze casting with a pressure of 62 MPa. Tensile, impact and density tests were carried out on the specimens. It was found that casting temperature had an effect on the mechanical properties of both gravity cast and squeeze cast aluminium and zinc alloys. The best temperatures to gravity cast the aluminium alloy and the zinc alloy were 720 and 460 °C, respectively. For the squeeze casting of the aluminium alloy, the best temperature to use was either 690 or 660 °C; the former would give a better property at the top of the casting while the latter, at the bottom of the casting. However, for the squeeze casting of the zinc alloy, the best temperature was again 460 °C.     

挤压铸造对Al-Cu合金显微组织及溶质分布的影响

研究了挤压铸造工艺条件下,工艺参数对Al-5Cu-0.4Mn合金显微组织及Cu元素分布的影响。结果表明,合金在25MPa压力下成形时,初生α-Al晶粒尺寸得到明显细化;浇注温度越高组织变得越粗大;升高模具预热温度,晶粒尺寸增大且分布不均匀。挤压铸造改变重力铸造条件下Cu的逆偏析现象,从铸件边缘往心部的Cu含量呈现增加的趋势,主要原因为晶间富铜液相在压力的强制补缩下,通过枝晶骨架通道被挤向铸件内侧。Cu在α-Al基体中的固溶度随着压力的增大而增加;沿径向远离铸件心部,α-Al晶内Cu含量逐渐增加。在挤压力为100MPa、浇注温度为680～730℃、模具温度为200℃的工艺条件下,可获得晶粒细小、组织致密、宏观偏析少的Al-5Cu-0.4Mn合金挤压铸件。     

铝合金轮毂连接盘挤压铸造数值模拟

采用ProCAST软件对6061铝合金轮毂连接盘挤压铸造过程进行模拟.研究了浇注温度、模具预热温度、比压对铸件缩孔缩松的影响.结果 表明,浇注温度700℃、模具预热温度300℃、比压50MPa为最佳铸造方案.     

Effect of specific pressure on microstructure and mechanical properties of squeeze casting ZA27 alloy

The effect of specific pressure on the microstructure and mechanical properties of ZA27 squeezed castings with high height-to-thickness ratio was studied. The results of DTA and SEM show that at high specific pressure the eutectic reaction of squeeze casting ZA27 alloy is restrained, and the final solidified structure is (η+ε) phases instead of eutectic phase (β+η+ε). At the same time, the primary reaction is promoted in squeeze casting ZA27 alloy solidified at high pressure, and the fine microstructure is obtained with the increase of pressure. Al and Cu elements are homogeneously distributed in matrix of squeeze casting ZA27 alloy. The homogenously distributed high-density fine ε phase can effectively hinder dislocation motion, and then the strength and plasticity of squeeze casting ZA27 alloy are increased.     

Optimization of squeeze cast parameters of LM6 aluminium alloy for surface roughness using Taguchi method

The ability to produce near net shape components with good surface finish is made possible by means of squeeze casting, a hybrid metal forming process combining features of both casting and forging in a single operation. The primary objective of this paper is to analyze the influence of the process parameters on surface roughness in squeeze casting of LM6 aluminium alloy using Taguchi method. In Taguchi method, a three level orthogonal array has been used to determine the S/N ratio. Analysis of variance and the ‘F’-test values are used to determine the most significant process parameters affecting the surface roughness. The results indicated that the squeeze pressure and the die preheating temperature are the recognized parameters to cause appreciable improvement in the surface finish of the squeeze cast components.     

不同压力下挤压铸造铝铜合金的组织与性能

采用挤压铸造工艺制备出一种新开发的、高强韧铝铜合金.T5热处理状态下其抗拉强度达到433 MPa,伸长率为14%.通过对该合金力学性能及其显微组织的研究表明,铸态和经T5热处理的抗拉强度和伸长率均随压力的增加而增大,在压力为50MPa时达到最大值,但在铸态下,未加压力的铸造合金其硬度高于挤压铸造的合金硬度.随挤压力增加,晶粒明显细化,二次枝晶增加,枝晶间距减小.     

Semi-solid squeeze casting process of a ZL109 alloy

The structure evolution of the ZL109 alloy in the process of semi-solid squeeze casting and the mechanical properties of the components were investigated. The results show that (1) the eutectic silicon phase in original billets is refined in the low super-heat casting process; (2) the eutectic structure in billets starts to fuse and the crystals of the eutectic silicon phase are refined further and sphericized in the remelting process of billets; (3) in the semi-solid ,squeeze casting process, the sphericity of the α phase and the refining of the silicon phase occur, owing to the friction between solid and liquid; (4) in the process of heat treatment, the eutectic α phase aggregates with the primary α phase and the eutectic silicon pieces aggregate together. The elongation of the semi-solid component after heat treatment rises to 1.42%.     

Studies on eutectic Al–Si alloy–flyash composites

Abstract

In this investigation, an attempt was made to study the influence of melt treatments like grain refinement and modification on the mechanical properties of cenospheres of flyash–LM6 composites. Stir casting route was employed to disperse the flyash (1–15?wt‐%) in the LM6 alloy matrix. For each percentage of flyash, melts were subjected to grain refinement, modification or combined grain refinement and modification. The results reveal that castings subjected to melt treatments showed increased hardness, ultimate tensile strength and elongation compared with untreated Al–Si base alloy up to 10% flyash. Addition of flyash beyond 10% resulted in decreases in hardness and ultimate tensile strength. Percentage elongation showed a decreasing trend for all the cases studied. Nevertheless, in all the cases studied, mechanical properties were higher than that of the Al–Si base alloy. Among all the composites, the best results were obtained with 10% flyash subjected to modification alone.     

浇注条件对Al-Cu合金组织的影响

利用扫描电镜和金相显微镜等手段，研究了浇注温度和冷却速度对Al—Cu合金组织的影响。结果发现，在Cu质量分数含量为5．65％的合金组织中出现了共晶组织，并随着浇注温度的升高，共晶组织体积分数明显增加。这是因为在Al—cu合金熔体中存在着Al原子集团，随着熔体温度的升高，原子集团尺寸减小。而且发现随着冷却速度的减小，同一浇注温度下的同成分的合金组织中共晶组织体积分数减小，共晶层片间距的分布由集中变分散。     

Section thickness-dependent tensile properties of squeeze cast magnesium alloy AM60

The development of alternative casting processes is essential for the high demand of light weight magnesium components to be used in the automotive industry,which often contain different section thickn...     

用调压铸造改善ZL101A-T6合金力学性能

实验比较了重力铸造和调压铸造ZL101A-T6铝合金的力学性能。结果表明，在相同的熔铸工艺和热处理条件下，调压铸造试样的强度，特别是伸长率得到大幅度提高。     

应变速率对Sn-9Zn共晶合金拉伸性能的影响

Sn—9Zn合金室温的拉伸曲线上存在一个较宽的无加工硬化区域，合金的最大拉伸应力对应变速率敏感，随着应变速率的增加，最大拉伸应力增大，对应变速率与抗拉强度关系的拟合获得了这种合金的应变速率敏感指数为0．097．SEM观察表明，裂纹在棒状Zn与基体的界面处萌生．合金的拉伸断口特征随应变速率的增加从典型的韧窝状延性断裂向半解理脆性断裂过渡。     

超声半固态流变挤压成形Al-20Si-2Cu-0.4Mg-1Ni合金的组织特征(英文)

通过超声振动半固态流变挤压铸造工艺制造汽车空调压缩机铝硅合金斜盘零件,研究合金的组织特征。发现在Al20Si2Cu0.4Mg1Ni合金的组织中,除了通常具有的初晶Si和α(Al)+β-Si共晶相之外,还有非平衡α(Al)颗粒或枝晶。挤压铸造过程中的较快的冷却速度而非压力是非平衡α(Al)相形成的主要原因。在半固态浆料的制备过程中,超声振动的声压作用能促进非平衡α(Al)相在共晶温度以上生成,并生长为非枝晶颗粒。超声处理的过共晶AlSi合金中的非平衡α(Al)相由共晶温度以上生成的圆形α(Al)晶粒和少量共晶温度以下生成的细小α(Al)枝晶构成。由于超声振动的作用使α(Al)基体中的Si的固溶度增加,并使初晶Si的形成温度降低,组织中初晶Si颗粒的体积分数显著降低。流变挤压斜盘中的初晶Si颗粒的平均直径和体积率分别为24.3μm和11.1%。