辅助垫片对铝/钢电阻铆焊接头性能的影响

为提高接头强度,在铝合金与钢的电阻铆焊中施加辅助垫片以扩大铆钉肩部与上板铝合金的接触面.观察、分析了接头中各界面的接合状态,探讨了焊接电流对接头抗剪力与十字抗拉力的影响.结果 表明:在施加辅助垫片的电阻铆焊接头中,铆钉肩部与辅助垫片、铆钉腿端部与下板铝合金之间都实现了熔合,在铆钉腿端部与铝合金的接合界面观察到了金属间化合物形成.施加辅助垫片的铝合金与钢电阻铆焊接头的抗剪力与十字抗拉力均随焊接电流的增大而呈先增大后下降的变化趋势,其最大值分别达7.51 kN和4.23 kN.     

辅助垫片对铝/钢电阻铆焊接头性能的影响

为提高接头强度,在铝合金与钢的电阻铆焊中施加辅助垫片以扩大铆钉肩部与上板铝合金的接触面.观察、分析了接头中各界面的接合状态,探讨了焊接电流对接头抗剪力与十字抗拉力的影响.结果 表明:在施加辅助垫片的电阻铆焊接头中,铆钉肩部与辅助垫片、铆钉腿端部与下板铝合金之间都实现了熔合,在铆钉腿端部与铝合金的接合界面观察到了金属间化合物形成.施加辅助垫片的铝合金与钢电阻铆焊接头的抗剪力与十字抗拉力均随焊接电流的增大而呈先增大后下降的变化趋势,其最大值分别达7.51 kN和4.23 kN.     

基于定位电极的铝合金/钢电阻铆焊接头的组织与性能

采用自冲铆与电阻点焊的复合连接工艺焊接铝合金与钢,点焊中以定位电极为下电极以保证电极与铆钉的同轴度。分析了接头中各界面接合状态,探讨了焊接电流对接头的断面特征参量和抗剪载荷的影响。在所得电阻铆焊接头中,铆钉腿与周边金属实现了冶金结合。当采用直径为10 mm的上电极,焊接电流为10 kA时,接头的抗剪载荷达到6.78 kN。结果表明：采用定位电极对铝合金A6061与低碳钢Q235自冲铆接头进行点焊可提升接头性能。     

凹模形状对铝合金/钢电阻铆焊接头性能的影响

采用3种不同形状的凹模对铝合金/钢进行了自冲铆连接,随后对其自冲铆接头进行了电阻点焊,研究了凹模形状和焊接电流对接头的抗剪载荷和十字抗拉载荷的影响,观察并分析了电阻铆焊接头界面接合状态.结果 表明:中心呈正态分布曲面的凹模的自冲铆接头性能较好,在铆接压力为24 kN时接头性能达到最优,其抗剪载荷和十字抗拉载荷分别为5....     

基于镁质铆钉的铝合金/镁合金电阻单元焊接接头的组织与性能

受形成于接合界面的金属间化合物的影响，铝合金与镁合金的电阻点焊接头性能难以达到工程应用的要求。为了提高接头的性能、拓宽铝合金/镁合金点焊的应用，分别以腿径为4、6、8与10 mm的镁质铆钉为单元件对AZ31B镁合金与A6061铝合金进行电阻单元焊，并利用扫描电镜观察了接头界面区域的组织，研究了焊接电流和焊接时间对接头抗剪载荷的影响。结果表明：接头中的铆钉帽/上板铝合金、铆钉腿/上板铝合金、上板铝合金/下板镁合金界面处形成了反应物层，主要由Al₁₂Mg₁₇构成，其厚度因位置不同而有所不同。随焊接电流、焊接时间的增大，A6061/AZ61B-REW接头熔核直径增大，抗剪载荷呈先增大后降低的变化趋势；当采用10 mm腿径的铆钉，在焊接电流为25 kA、焊接时间为160 ms以及4.8 kN的电极压力进行焊接时，焊接接头的抗剪载荷最大，约为5.19 kN。     

以铝质铆钉为单元件的铝合金/钢的电阻单元焊

以腿径为6 mm的铝质铆钉为单元件对铝合金A6061与低碳钢Q235进行电阻单元焊，并利用扫描电镜对接头界面区域进行了组织观察，研究了焊接电流、焊接时间对接头抗剪载荷和十字抗拉载荷的影响。结果表明：焊接电流大于18 kA时，靠近熔核的铆钉腿与上板钢的界面、上板钢与下板铝合金间界面生成了金属间化合物层。随着焊接电流增大、焊接时间的增加，接头的抗剪载荷和十字抗拉载荷均呈先增大后下降的变化趋势；当焊接电流为26 kA、焊接时间为300 ms、电极压力为3.1 kN时，接头的抗剪载荷达到最大，其值约为5.86 kN。     

基于铆钉辅助的铝合金/钢电阻点焊接头的组织与性能

为提高铝合金/钢接头强度,在电阻点焊中引入一个具有端帽的钢制铆钉。改变铆钉腿径、焊接电流等参数对铝合金/钢进行焊接,观察并分析了其焊接接头各区域微观结构,探讨了焊接条件对接头性能的影响。结果表明：当采用的铆钉腿径为8 mm,焊接电流为14 kA时,接头的抗剪载荷和十字抗拉载荷分别达到6.31 kN和4.10 kN。在具有端帽的铆钉辅助下,对铝合金A6061与低碳钢Q235进行点焊可获得性能较高的接头。     

纯钛/铝合金A6061电阻点焊接头性能

采用电阻点焊焊接纯钛与铝合金A6061,探讨焊接电流、焊接时间与电极压力对熔核尺寸和接头抗剪力的影响,观察分析接合界面微观组织特征。接头熔核直径随焊接电流增大而增大,而抗剪载荷随焊接电流的增加先上升后下降趋势变化;而接头随焊接时间的延长、电极压力的减小,熔核直径和抗剪载荷而增加。焊接时间为25 cyc时所得接头的抗剪载荷最大,约为7.6 kN。结果显示母材铝合金中Si能抑制界面金属间化合物的生成,改善接头性能。     

铝合金与低碳钢的复合电极电阻点焊接头特性

针对铝/钢难以焊接这一课题,研发了基于复合电极的电阻点焊新工艺,并对铝合金A6061与低碳钢Q235进行了点焊. 介绍了复合电极的设计、制造流程,观察分析了结合界面区反应层形貌及分布等微观组织特点,探讨了焊接电流对熔核尺寸和接头抗剪载荷的影响. 在结合界面上观察到了反应层的生成,其厚度随位置的变化而变化. 焊接接头熔核直径与抗剪载荷随焊接电流的增加而增大. 结果表明,在铝合金与低碳钢的电阻点焊中,镶嵌式复合电极的使用能够起到抑制界面反应层在焊点中央区域生长的效果.     

铆钉硬度对铝合金/钢电阻铆焊接头性能的影响

采用电阻铆焊的方法对A5052铝合金和Q235低碳钢进行焊接，分析了自冲铆铆钉的硬度和焊接参数对电阻铆焊接头的宏观形貌和力学性能以及铆钉腿端部与下板间的接合状态的影响。结果表明：采用高硬度铆钉(HRC为42±1)的电阻铆焊接头中形成的孔洞缺陷较少，其宏观形貌优于采用中等硬度(HRC为36±1)和较低硬度(HRC为33±1)铆钉的焊接接头。采用高硬度铆钉焊接时，随着焊接电流的增大，残留于铆钉腿端部与下板间的铝合金变薄。当焊接电流为10 kA,焊接时间为400 ms时，高硬度铆钉的焊接接头的最大抗剪力为7.67 kN。     

Influence of resistance heating on self-piercing riveted dissimilar joints of AA6061-T6 and galvanized DP590

The hybrid use of aluminum alloy and advanced high strength steel (AHSS) has become an inevitable trend for fabricating a lightweight auto-body. Self-piercing riveting (SPR) as a preferred cold-forming fastening method is facing problem like weak interlocking when joining dissimilar combinations with considerably unequal thickness. In this study, a hybrid joining method, named rivet-welding (RW) was proposed to improve the robustness and strength of the SPR joint, by applying an electric current to it. For better evaluating the new process, the effects of heating time and electrode design on the microstructure, micro-hardness distribution, and mechanical performance of the RW joints were studied and compared systematically with the traditional SPR ones. The results showed that the electric current could improve the microstructure of the steel rivet and bottom DP590, and under long heating time, the inter-metallic compounds (IMC) could be formed at the interface of trapped AA6061-T6 and bottom DP590. Meanwhile, the electric current could increase the micro-hardness of the rivet and bottom DP590, and soften the AA6061-T6 around the rivet leg. In addition, the RW process using lower annular electrode A (LAE_A) could obtain 12.1% higher tensile-shear strength compared with the traditional SPR process.     

纯铝中间层厚度对铝/钢点焊接头性能的影响

采用纯铝作为中间层对铝合金与低碳钢进行了电阻点焊,分析中间夹层厚度对界面反应层厚度和接头抗拉强度的影响。在钢/中间夹层界面观察到有界面反应层生成,其主要由靠近钢侧的Fe2Al5和靠近中间夹层铝侧的FeAl3两种金属间化合物组成。与不加中间夹层相比,利用纯铝作为中间夹层点焊的铝合金与低碳钢的接头具有较薄的界面反应层和较高的接合强度。随着中间夹层厚度的增加,界面反应层厚度逐渐减小,而接头抗拉强度则呈增大趋势。结果表明,采用纯铝作为中间夹层点焊铝合金与钢具有一定的有效性。     

Interfacial microstructure and strength of steel/aluminum alloy joints welded by resistance spot welding with cover plate

We joined aluminum alloy A5052 to cold-rolled steel SPCC (Steel Plate Cold Commercial) and austenitic stainless steel SUS304 using resistance spot welding with a cover plate. The interfacial microstructure was observed using transmission electron microscopy. A thick two-layered reaction layer contains Fe₂Al₅ and FeAl₃ and a thin serration reaction layer contains Fe₂Al₅ and FeAl₃ were observed at the A5052/SPCC and A5052/SUS304 interface, respectively. Mechanical property analysis suggested that the reaction layer has no effect on the tensile shear strength of the A5052/SUS304 joint and that the tensile shear strength of the A5052/SPCC joint is influenced by the reaction layer formed at its interface.     

Interfacial characterization of resistance spot welded joint of steel and aluminum alloy

The dissimilar material resistance spot welding of galvanized high strength steel and aluminum alloy had been conducted. The welded joint exhibited a thin reaction layer composed of Fe2Al5 and Fe4Al13 phases at steel/aluminum interface. The welded joint presented a tensile shear load of 3.3 kN with an aluminum alloy nugget diameter of 5.7 ram. The interfucial failure mode was observed for the tensile shear specimen and fracture occurred at reaction layer and aluminum alloy fusion zone beside the interface. The reaction layer with compounds was the main reason for reduction of the welded joint mechanical property.     

铝合金与不锈钢电阻点焊接合界面区的组织特性

采用热补偿工艺垫片电阻点焊法对铝合金A5052与不锈钢SUS304异种材料进行了焊接．通过电子显微镜对接合界面区进行了观察，并分析了所生成反应物的微观结构及分布等组织特性．结果表明，一锯齿状反应层在接合界面生成，其主要由Fe2Al5和FeAl3组成；反应层厚度随焊接电流以及界面上位置的变化而变化．另外，在界面附近的铝合...     

电磁铆接试样质量分析

采用试验方法,通过电磁铆接和气动铆接方式,对铆接试样从铆钉宏观变形和微观连接方面进行质量对比分析。结果表明,与气动铆接相比,电磁铆接能一次成形,铆接试样钉杆变形均匀,波动度小,铆接质量稳定,不易出现钉头被铆歪、开裂等现象。在铆钉成形钉头与铝合金板连接处,电磁铆接铆钉变形较气动铆接剧烈。在铆钉钉杆与铝合金板连接处,电磁铆接试样铆钉与铝合金板连接的紧密程度要好于气动铆接。在铆钉钉杆与复合材料连接处,电磁铆接铆钉对复合材料的挤压程度要小于气动铆接,未出现复合材料分层和开裂。     

Brazing zirconium alloys with an amorphous rapidly quenched strip brazing alloy

Application of aluminum alloy, which is a typical lightweight material, has been expected to achieve energy saving and prevention of pollution in many kinds of transportation vehicles. While the structure made of whole aluminum alloy, however, is lightweight, it still has problems, such as low mechanical strength and high cost. Hence, a hybrid or joining structure made of aluminum alloy and steel seems to be reasonable because of its light weight and higher strength.

To make a hybrid structure for transportation vehicles, we examined welding by friction stirring between aluminum alloy and low-carbon steel, which could be welded without melted weld materials. As a result, welding between aluminum alloy and low-carbon steel that had a thin intermetallic compound at the weld interface was obtained.

In recent automobile manufacturing, zinc-coated steel has been used for structural parts in general. On welding between zinc-coated steel and other materials such as aluminum alloy, existence of a Zn layer between aluminum and steel has to be taken into account to get a high-quality joint between the materials.

In this study, spot joining between aluminum alloy and several kinds of zinc-coated steels by friction stirring was carried out, and the effect of the coated layer both on the weld strength and weld interface microstructure was investigated. As a result, the joint between aluminum alloy and zinc-coated steel was stronger than that between aluminum alloy and non-coated steel, when the coated layer was removed at the weld interface by plastic flow of aluminum alloy.     

AZ31镁合金与钢异种金属的焊接技术

采用电阻点焊作为热源,进行AZ31镁合金与Q235钢的直接连接。通过扫描电镜、金相显微镜以及万能实验机分析与测试镁-钢点焊接头的微观组织、界面特性以及拉剪性能。研究表明,虽然镁和铁之间几乎不能互溶和形成金属间化合物,但氧和铝元素在镁合金-钢直接电阻点焊中起决定性作用,在镁-钢界面某些区域促进了以镁、铝、氧以及铁元素组成的复杂元素扩散层的形成,而镁、钢之间物理性能的巨大差异在一定程度上限制了界面反应的均匀性,接头拉剪强度约为40 MPa。     

铝合金与树脂基复合材料连接技术综述

在航空航天、海洋运输和车辆制造等领域,制造材料朝着轻量化、复合化和高性能化的方向发展.由于铝合金和树脂基复合材料具有高比模量和高比强度等优点,其复合结构的连接技术也受到越来越多的关注.本文针对铝合金与树脂基复合材料连接技术的连接机理和影响因素进行综述.目前,铝合金和树脂基复合材料的连接方法主要为螺栓连接、铆接、胶接、注...     

Wetting Characteristics of Novel-type 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi Solder Alloy

6061 aluminum alloy has many advantages, and soldering is the most attractive joining method for 6061 aluminum alloy. In order to expand application of 6061 aluminum alloy, a novel 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi solder alloy was prepared. The melting characteristic and microstructure of the solder were analyzed by differential scanning calorimetry and scanning electron microscope. Its spreading on the 6061 aluminum alloy was also studied. The results show that its melting temperature range is 456.34-463.68 K, and the temperature interval between the solidus and the liquidus is 6.34 K. The solder on 6061 aluminum alloy had better wetting characteristics. A precursor film appears ahead of the spreading droplet. The microstructure at the interface between the solder and the 6061 aluminum alloy was analyzed. It was clear that the intermetallic compound, Ag₂Al phase, was formed at the interface between the solder and the 6061 aluminum alloy.