轿车铝合金轮毂的液态模锻

提出了轿车铝合金轮毂液态模锻工艺，并试验验证了新工艺实现条件及工艺措施，产品性能优于目前的低压铸造法，设备简单，具有良好的经济效益。     

铝合金熔炼过程中采用电磁泵搅拌的优点

介绍电磁泵在铝合金熔炼中的应用状况及采用电磁泵搅拌铝熔体的主要优点。电磁泵搅拌铝熔体在许多大铝业公司已采用。它具有减小铝合金熔体温度差,提高铝合金炉料熔化速度,使熔体成分均匀,降低能耗等优点。     

Forming of aluminium alloy at temperatures just below melting point

In order to improve the mechanical properties of products, a forming process of a solid material at a temperature just below the melting point is proposed. The material is deformed at the semi-solid temperature due to the heat generation caused by plastic deformation. The tensile strength, elongation, hardness and toughness of the aluminium alloy (Al–7%Si–0.3%Mg) billet extruded at temperatures between 500 and 550 °C are compared with those of the billet extruded in the hot forming (450 °C) and the semi-solid (560 °C) temperatures. The billet temperature during forming is evaluated by the finite element simulation. The tensile strength and hardness of the billet extruded at 550 °C just below the solidus temperature are higher than those for a billet at 450 °C, and they are almost the same as those for a billet deformed at 560 °C in the semi-solid region. The elongation and toughness of the extruded billet at 550 °C are lower than those for a billet at 450 °C. The forming load at 550 °C is almost half of that at 450 °C. Cracking on the surface of the extruded billet occurs at a high punch speed. The calculated temperature when the solid billet is extruded in the semi-solid state agrees well with the experimental one at which the tensile and hardness are improved.     

Solid-state recycling of aluminium alloy swarf through cold profile extrusion and cold rolling

In this study, the possibility of solid-state recycling of aluminium alloy machining swarf using cold extrusion and a subsequent cold rolling process is investigated. Cast Al-Si alloy swarf was cold compacted into billets and successfully profile-extruded into square bars with a rectangular cross-sectional aspect ratio of 1:1.8 under an extrusion ratio of 4 or more. After annealing, the extruded bars underwent multi-pass cold rolling into 1-mm thick strips with a total rolling reduction of 85%. Optical microscopy demonstrated that in material recycled using only an extrusion process, coarse residual voids existed in regions where insufficient plastic strain was introduced, causing a visible expansion of the material during heat treatment. However, uniaxial tensile tests showed that extrusion-recycled material had a higher mechanical strength than the original aluminium alloy, implying sufficient bonding among the individual pieces of machining swarf. It was also found that the strength and density of material recycled through extrusion and an additional rolling process were superior to material recycled using extrusion only. Moreover, it was observed that the ductility of the recycled materials was inferior to that of the original aluminium alloy.     

KF-AlF3-KBr低熔点铝基钎剂研制

氟铝酸钾钎剂不吸潮、无腐蚀,广泛应用于铝及其合金的钎焊,但由于该钎剂熔点较高,限制了其使用范围。在KF-AlF3钎剂基础上,添加第三组元KBr降低了熔点,获得了低熔点的无腐蚀性钎剂。通过DSC、XRD和一系列钎焊性能实验表明,当w(KBr)=20%时钎剂熔点最低,液相线温度522.1℃。钎剂由KAlF4、K3AlF6和KAlBr4组成,KAlF4-K3AlF6-KAlBr4组成的三元共晶是钎剂熔点降低的主要原因。通过性能测试表明,此钎剂具有良好的铺展性、填缝性,去膜能力也有较大程度的提高,可以应用于低熔点铝合金钎焊。     

单一成分活性剂对铝合金作用效果的研究

活性化TIG(A-TIG)焊已成为近年来的研究热点,但主要集中在不锈钢和钛合金两种材料,在铝合金中的应用较少.针对铝合金A-TIG焊进行了初步的研究和探索,选择四种单一成分的活性剂,采用表面两侧涂敷方式,通过2A14铝合金的平板堆焊实验,研究了在相同规范下不同活性剂对焊缝熔深、焊缝成形、气孔和微观组织的影响.实验结果表...     

大尺寸喷射沉积7075铝合金楔压致密化工艺

用喷射沉积工艺制备大尺寸7075铝合金坯,探索楔压致密化工艺,研究楔压变形量和变形温度对材料组织及性能的影响。结果表明,采用局部变形、多道次小变形累积实现大变形的楔形压制工艺,能有效实现喷射沉积铝合金坯件的致密化,合适的工艺参数楔压温度为420℃~470℃,楔压变形60%;材料的相对密度为99.6%,布氏硬度为138.4,室温拉伸强度为395MPa,延伸率为6.15%,且组织和性能分布均匀。     

4032铝合金钠盐变质工艺研究

试验研究了4032铝合金钠盐变质工艺。对钠盐变质后的4032铝合金铸锭的低倍组织、断口形貌、显微组织、力学性能等进行分析,为合理制定钠盐变质处理工艺提供理论和试验依据。     

2A50铝合金等径角挤压后的微观组织和电导率

采用自行设计的模具,对铝合金2A50进行等径角挤压,模具的交角为120°,相邻两次挤压,试样顺时针方向旋转90°,并研究挤压后2A50铝合金的微观组织和物理性能.结果表明:在室温下可以对2A50铝合金实行多道次挤压,挤压后材料的晶粒平均尺寸下降到164nm,达到亚微米级,同时,硬度明显增大,综合力学性能提高,但是电导率急剧下降,经过3次挤压后,2A50铝合金的电导率由原始的18784.63S/M迅速下降到3553.27S/M.     

无润滑挤压铝合金管材时铸锭长度的确定

根据对穿孔针所受拉力的计算,得出如何确定无润滑挤压铝合金管材时合理的铸锭长度,以减少挤压时的断针现象.     

铝合金与不锈钢钎焊用钎剂性能研究

针对Al及其合金与不绣钢钎焊中存在的因钎剂的腐蚀性及钎料的润湿性等引起钎焊接头强度下降的问题，研制出一种以LiCl-NaCl为基，并配以其它成分的Al基钎剂。对钎剂的配制机理进行了分析，并用试验的方法对其钎焊性能进行了研究。对钎焊接头及其界面作扫描电镜(SEM)、透射电镜(TEM)、X射线衍射和拉力试验等分析发现，钎剂对钎料的润湿性能良好，有效地阻止了钎料在钎焊期间的氧化。对接头进行腐蚀性试验，发现焊缝的抗腐蚀性较强，能够满足一般环境的使用要求。     

Experimental study on turning of TC9 titanium alloy with cold water mist jet cooling

Titanium alloys, as difficult-to-cut materials, have poor machinability due to their superior mechanical properties, heat resistance and corrosion resistance. High cutting temperature that will greatly accelerate tool wear often occurs in titanium alloy cutting process. In this paper, cold water mist jet (CWMJ) cooling method, an eco-friendly cooling method, was used to obtain a lower cutting temperature during TC9 titanium alloy turning process. The effects of CWMJ were mainly discussed as compared with cold air jet and flood cooling methods. A comprehensive evaluation on the cooling effects of CWMJ was carried out by hydrodynamic tests, heat transfer tests and turning tests, respectively. Experimental results indicated that CWMJ had better cooling effects as compared with other two cooling methods. Cutting temperature was greatly reduced, and tool life was improved with CWMJ during TC9 turning process. Machined surface quality and chip morphology were also acceptable.     

Synthesis of TiC composite by salt route and grain refinement of aluminium alloy

Abstract

The synthesis of Al–3Ti–0˙75C master alloy grain refiner was carried out by adding K₂TiF₆ and graphite powder together in aluminium melt from 800 to 1200°C. The reaction between the halide salts and graphite in aluminium melt was also carried out at different time intervals at 1200°C. The in situ formation of TiC particles in the Al/K₂TiF₆/graphite system involved the formation of Al₃Ti followed by formation of TiC at varying temperature and time. It is observed that TiC and Al₃Ti phases together showed the best grain refining efficiency in comparison to only by TiC or Al₃Ti alone.     

Issues in the melting and reclamation of aluminum scrap

The processing of aluminum scrap has been practiced for as long as aluminum has been produced due to the inherent value of the metal and the amount of energy required to produce primary aluminum from bauxite ore. Scrap can be remelted at a fraction of the expense. With the large-scale introduction of aluminum beverage containers in the 1970s, increases in energy costs, and the need to reduce solid waste, aluminum recycling has grown at an increasing rate. This article provides a overview of the technologies and issues that surround the melting and reclamation of aluminum scrap.     

Effect of cold flakes on mechanical properties of aluminium alloy die casts

Abstract

The cold flake was detected in aluminium alloy die casts ADC12 by using the scanning acoustic microscope, and was visualised in the acoustic image as bright and dark regions, which were corresponding to the oxide layer and the body of the cold flake respectively. By using the specimen which contains the cold flake, the tensile testing and the fatigue testing were carried out. The in process ultrasonic measurement was also carried out with a water bag in the fatigue testing to detect detachment of the cold flake from the matrix in the fatigue process. From these results, it was found that the cold flake was detached from the matrix in the fatigue process to form a crack, and cold flakes, especially exposed cold flakes, reduce the tensile strength and the fatigue life of die casts. The effect of the cold flake on the strengths was discussed from the point of crack propagation.     

电子束冷床熔炼TC4合金温度场模拟

利用ANSYS软件对电子束冷床熔炼TC4钛合金过程进行模拟研究.结果表明:熔体从冷床滴入坩埚之后,主要出现熔体升温、形成稳定熔池、熔体凝固、熔体温度下降和凝固结束这5个阶段.在开始熔炼时,熔体温度较低,升温也比较慢,但随着熔炼的进行,熔体升温加快,并维持在高温状态,最后熔体发生凝固降温,且降温速度很快.降温过程主要分为两个阶段,在快速降温阶段,熔体快速出现部分凝固,而在降温平衡阶段,熔体主要进行补缩.当降温时间达到500 s时,熔体温度基本保持不变.     

模具结构对反复模压变形5052铝合金显微组织的影响

在自制的新型组合式模具上对商业5052铝合金板材进行两种不同结构模具下的反复模压变形,并用光学显微镜和透射电镜对变形合金进行显微组织分析。结果表明:限制模压(Constrained Groove Pressing,CGP)变形和非限制模压(UnconstrainedGroove Pressing,UGP)变形均能够有效细化5052铝合金,其平均晶粒尺寸随变形道次的增加而减小。在两种不同结构模具的反复模压变形下,5052铝合金呈现出不同的组织特征。经CGP变形后合金组织基本由破碎的等轴小晶粒构成,形成包含高密度位错的等轴状亚晶;而经UGP变形后,形成类似于冷轧变形金属组织的拉长晶粒和具有较大取向差的包含高密度位错的带状亚结构。与UGP相比,CGP更有利于晶粒细化和形成等轴晶粒。     

波纹曲面冷压对7050铝合金带筋厚板残余应力的影响

通过淬火、冷压试验和有限元模拟,研究了波纹曲面结构对7050铝合金带筋厚板淬火、冷压后消减残余应力的影响规律,分析了变形量、波纹方向及波纹形状对冷压后残余应力消减效果的影响.结果表明,波纹曲面结构对淬火残余应力分布的影响不明显,冷压后残余应力得到了较大消减.随着变形量的增大,筋条及试样两侧棱位置的压应力区面积及应力值下...     

2024 aluminium alloy wettability and superficial cleaning improvement by air cold plasma treatment

2024 aluminium alloy is used for parts and structures which demand high-strength/weight ratio. In particular, Al2024 is, for its high specific strength and good chemical stability, a suitable material for aerospace application. Aluminium alloys are involved in corrosive phenomena when they are used in critical applications, such as the aeronautic ones. The solution commonly adopted to solve corrosive problems is to paint aluminium alloy surface including 2024 aluminium alloy which is the subject of this study. The applied paint film protects the aluminium alloy from corrosion. In order to improve the adhesion of the paint film it is necessary to pre-treat the manufactured surface. The objective of the pre-treatment is to develop a cleaned, uniform, wettable surface. Cold plasma is an efficient, economic and environmentally attractive alternative to the use of the traditional pre-treatment. This work aims to study the relationship between cold plasma and 2024 aluminium alloy wettability and cleaning. Surface samples have been analysed by: (i) standard procedure to measure the quantitative wettability; (ii) Energy Dispersive X-ray Spectroscopy or EDS to determine a quantitative measure of organic contaminant.This work demonstrates that air cold plasma treatment improves significantly wettability and cleaning of 2024 aluminium alloy surfaces both associated with pre-cleaning by MEK^® and without pre-cleaning by MEK^®: the wettability reducing has been greater than 70% and the contaminants reducing greater than 65%.     

用煤气炉熔化液体料生产5A06铝合金扁锭工艺研究

通过对煤气炉熔化液体料生产5A06铝合金扁铸锭与电炉自投固体料熔化生产铸锭,进行全分析、力学性能、成品板材探伤各个方面对比,确定用煤气炉熔化料生产的5A06成品板材能否满足用户的使用要求.