铝合金-碳钢管的磁脉冲变形连接(英文)

采用带集磁器线圈装置对3A21铝合金20钢管件进行磁脉冲连接,并对连接接头的力学性能和微观结构进行测试和观察。结果表明,在电压为15kV、径向间隙为1.2~1.4mm和搭接区锥角为3°~7°的条件下可获得冶金连接接头。连接接头由宽度不均匀的过渡区、两母材及其与母材连接的界面构成。连接界面呈微波状形貌,过渡区发生基体元素Fe和Al的互扩散。过渡区由FeAl金属间化合物构成,并存在微裂纹和微孔洞等缺陷;其显微硬度明显高于邻近母材的显微硬度。     

铝-铜平板磁脉冲焊接工艺研究

采用磁脉冲焊接技术对铝-铜异种金属板材进行了焊接试验,研究了放电电压和两板之间的间隙对接头抗剪强度及焊缝宽度的影响。结果表明:接头焊缝呈扁平椭圆形。焊接间隙为1.4 mm时,从整体上看,焊缝宽度与接头抗剪强度随着放电电压的增加而增大;放电电压为11 kV时,焊缝宽度和接头抗剪强度随着焊接间隙的增加先增大后减小。在接头界面微区,铝铜两种元素发生了相互扩散,未发现金属间化合物的产生,其硬度值随着距界面距离的增加而降低。     

摩擦增材辅助Ti/Al搅拌摩擦搭接接头特征分析

为解决Ti/Al异种材料搅拌摩擦焊接接头强度低、搅拌针磨损等问题,提出一种摩擦增材辅助搅拌摩擦搭接焊(friction addition-friction stir lap welding, FA-FSLW)技术. 该新工艺延续了固相连接的优势,具有热输入量低、界面金属间化合物薄等特点.文中研究了以6082铝合金作预沉积层辅助实现3 mm厚2A12铝合金板与4 mm厚TC4钛合金板之间的连接,焊接过程中搅拌头扎入铝沉积层而不接触钛表面,得到抗拉载荷最大为12.2 kN的接头.结果表明, FA-FSLW复合焊接头的界面迁移越大,接头承载越小.同时,发现界面处的Ti, Al元素发生了明显互扩散,Si元素在界面偏聚,与Ti, Al元素发生冶金反应后形成层状纳米级Ti-Al-Si金属间化合物,为提高接头强度奠定基础.     

连接参数对Bi系(BSCCO)超导带材扩散连接接头性能的影响

采用高温直接加压退火工艺扩散连接61芯Bi系高温超导带材。研究了835℃连接温度下接头搭接长度、搭接区窗口的台阶数、保温时间对接头结合界面特征及其超导电性的影响。结果表明,连接参数对接头超导电性Ic影响明显,超导电性低的接头其超导芯结合界面处有未焊合迹象,母材经过835℃扩散连接热循环后超导电性显著降低。     

2099-T83/2060-T8异质Al-Li合金搅拌摩擦焊搭接界面结构与力学性能

采用搅拌摩擦焊(FSW)对厚度为2 mm的2099-T83与2060-T8 Al-Li合金进行搭接.利用OM和SEM等分析技术探讨搅拌头转速和搅拌针长度对搭接接头界面结构与力学性能的影响.结果表明,2099-T83/2060-T8搭接接头焊缝区可观察到明显的结合界面,焊缝区显微硬度低于母材,且在热机影响区与焊核区的过渡区硬度最低.当搅拌头转速由600 r/min增加到800 r/min,且搅拌针长度由3.0 mm减小至2.5 mm时,界面形貌由光滑界面转变成"锯齿状"咬合界面,焊缝区结合界面形貌主要受搅拌针长度影响,"锯齿状"咬合界面搭接接头平均破坏载荷为654 N.搭接接头均在底部母材2060-T8侧热机影响区与焊核区的过渡区断裂,断裂特征为韧-脆混合断裂."锯齿状"咬合界面搭接接头经150℃,保温20 h人工时效处理后,焊缝区显微硬度有所提升,接头承载能力较未经人工时效处理的降低了20%,断口呈现脆性断裂模式.     

镁钢无匙孔搅拌摩擦点焊工艺参数对接头扩散程度的影响

对DP600镀锌钢板和AZ31B镁合金板进行无匙孔搅拌摩擦搭接点焊试验,利用正交试验确定影响因素主次和最优试验方案,在最优焊接工艺下接头的拉伸载荷达到10.1 kN.通过分析接头宏观、微观形貌及界面元素分布,探讨不同工艺参数对接头元素扩散程度的影响,结果表明,搅拌区镁钢存在“弯钩”状的机械互锁结构,形成牢固的机械连接;扩散区镁钢发生了元素扩散,最优工艺参数下扩散层厚度为8 μm;在一定的范围内,增大搅拌头转速、轴肩下压量和搅拌针伸出量,可以促进元素之间的扩散,提高接头连接性能.     

铜/钢异种金属搅拌摩擦焊搭接工艺

采用SKD61模具钢搅拌头对2 mm厚铜/钢异种金属进行搅拌摩擦焊搭接,分析了搭接接头微观组织和力学性能. 结果表明,当搅拌针与钢母材直接接触时,随焊接过程的进行搅拌针不断磨损甚至发生断裂. 焊核区前进侧出现流线区域,在搭接界面结合处形成机械冶金结合. 显微硬度测试显示,铜侧焊核区硬度最高,在搭接界面处硬度分布呈中间高两边低的趋势,接头厚度方向搭接界面处硬度最高. 形成良好结合的搭接接头在拉剪试验中断裂于铜侧热影响区,拉伸断口存在大量韧窝,呈典型韧性断裂模式.     

钨铜/铍青铜异质钎焊界面组织与性能

采用BAg56CuZnSn,BAg50ZnCdCuNi和BAg49ZnCuMnNi银钎料实施了钨铜合金/铍青铜异质材料接头的感应钎焊连接,研究了其钎焊界面组织与力学性能.结果表明,3种银钎料均能获得完好界面钎焊接头,钎料与钨铜和铍青铜形成较好冶金结合.钎料与铍青铜界面冶金结合充分,形成明显互扩散区.钎料与钨铜钎焊界面清晰,且钎料向钨铜近界面区域形成明显扩散渗入现象.强度测试表明,BAg49ZnCuMnNi钎焊接头强度最高,达到250 MPa,接头断裂均发生在钨铜侧钎焊界面.分析表明,钎料向钨铜渗入明显促进界面结合,钎料中添加镍,由于镍与钨的扩散互溶进一步提高界面冶金结合,Mn元素添加明显细化钎缝晶粒,接头强度显著提升.     

几种铝钢异种金属熔钎焊工艺的对比与分析

采用脉冲旁路耦合电弧MIG焊、CMT及激光焊方法实现铝/镀锌钢板搭接焊,对焊缝界面微观组织、形貌及元素成分进行了观察分析,并测试了其力学性能.结果表明,三种焊接方法均可以实现铝/镀锌钢板异种金属的优质连接,获得成形良好的焊缝,搭接接头的抗拉剪强度均可以达到铝合金母材的80%以上,拉伸试样断裂在焊缝铝合金母材热影响区.当母材热输入及工艺合适时,三种方法下搭接接头界面处均形成一主要成分为Fe₂Al₅和FeAl₃,平均厚度约为8 μm的金属间化合物,而且控制金属间化合物的生成是获得铝/钢焊接优质接头的关键.     

影响铝合金搅拌摩擦焊搭接接头性能的因素

本文研究了搅拌摩擦焊搭接接头的界面形态和机械性能.连接了航天工业常用的板材铝合金2024-T3和7075-T6两种材料.通过观察接头横截面的金相和失效部位,发现所有接头都存在板间临界界面.因此,施加二次重复焊以消除板间临界界面.结果表明搅拌摩擦焊搭接接头在强度方面,具有取代其它类似电阻点焊和铆接等连接方法的潜能.     

A Novel Friction Stir Spot Riveting of Al/Cu Dissimilar Materials

In order to eliminate the disadvantages of the keyhole in conventional friction stir spot welding joint and attain the high-strength lap joint of Al/Cu dissimilar metals,a novel welding technique,named as friction stir spot riveting(FSSR),was proposed.A pinless tool and an extra filling stud were employed.The Al/Cu spot joints without keyhole defect were achieved by the FSSR.A Cu anchor-like structure was formed,which greatly increased the mechanical interlocking between the upper Al sheet and lower Cu sheet.The thin intermetallic compounds containing CuAl2 and CuAl at the Al/Cu interface strength-ened the joining interface between the Al sheet and the Cu stud.Increasing rotating velocity increased frictional heat and plastic deformation and then eliminated the interfacial joining defects.The FSSR joint with the maximum tensile shear load of 3.50 kN was achieved at a rotating velocity of 1800 rpm and a dwell time of 20 s,whose fracture path passed through the softened region of upper Al sheet.In summary,the novel FSSR technique has the advantages of strong mechanical interlock-ing and metallurgical bonding between dissimilar materials,thereby attaining the high-strength spot joint.     

Magnetic pulse cladding of aluminum alloy on mild steel tube

Bi-metal tubes, which combine the advantageous properties of two different metals, are desirable in industries where corrosion resistance is important. A new cladding method named magnetic pulse cladding (MPC) was used to form bi-metal tubes. A cladding of mild steel tube by aluminum alloy (AA3003) was achieved. The effect of the geometry of the field shaper on cladding quality was investigated as well as other main process parameters, such as, feeding size, radial gap and discharge voltage. The mechanical property was evaluated by compression-shear test and a maximum strength of 79.2 MPa and an average of 29.7 MPa were attained to by the following process settings: profiled field shaper, feeding size of 12 mm, radial gap of 2.0 mm and discharge voltage of 15 kV. OM and SEM images show a smooth integral interface and a small wavy one. EDS mapping reveals the interfacial diffusion zone up to 50-μm wide. The results show that the proposed MPC process is able to form sound cladding bonds and could be applicable to a tubular clad component with a high axial length.     

Friction stir keyholeless spot welding of AZ31 Mg alloy-mild steel

Friction stir keyholeless spot welding (FSKSW) using a retractable pin for 1.0 mm thick galvanized mild steel and 3 mm thick AZ31B magnesium alloy in a lap configuration was investigated. The process variables were optimized in terms of the joint strength. The effects of the stacking sequence on joint formation and the joining mechanism of FSKSW AZ31B-to-mild steel joints were also analyzed. It shows that the process window and joint strength are strongly influenced by the stacking sequence of the workpieces. While the process window is narrow and unstable for FSKSW of a magnesium-to-steel stack-up, a desirable process was established for the steel-to-magnesium stacking sequence, a desirable process and higher strength joint can be got when the steel-to-magnesium stacking sequence. XRD phase and EPMA analyses of the FSKSW joint showed that the intermetallic compounds are formed at the steel-to-magnesium interface, and the element diffusion between the mild steel and AZ31B magnesium alloy revealed that the joining methods for FSKSW joints is the main mechanical joining along with certain metallurgical bonding.     

Effect of anodizing on direct joining properties of aluminium alloy and plastic sheets by friction lap joining

We have proposed a novel joining process, friction lap joining (FLJ), to join metallic material sheet directly to polymer sheet and have investigated mechanical and metallurgical properties of these dissimilar joints. The joining mechanism is discussed with an evaluation of the TEM microstructure at the joint interface between A2017 aluminium alloy and two kinds of polymer, ethylene-acrylic acid copolymer (EAA), and high density polyethylene (PE). EAA sheet was easily joined to an as-received aluminium alloy sheet by FLJ, because EAA had a polar functional group, COOH. On the contrary, PE was not able to be joined to an as-received aluminium alloy, because PE had no polar functional group. However, anodizing of aluminium alloy was effective to join these materials by the assistance of the anchor effect.     

钛/钢复合板焊接技术研究现状及发展趋势

综合分析了已有钛/钢复合板焊接的研究成果,基于钛与钢焊接与连接的冶金特性,归纳总结并剖析了钛板搭接焊和对接焊、复合板过渡焊接工艺过程和焊缝金属冶金特点及相关力学性能,提出了未来钛/钢复合板焊接研究的重点发展方向及相关科学问题,希望对该领域的基础研究及工程应用提供有价值的参考.     

Approach to disrupting thick intermetallic compound interfacial layer in friction stir brazing (FSB) of Al/Cu plates

Friction stir brazing (FSB) was developed for dissimilar joining to overcome the problems associated with friction stir lap welding (e.g. pin wear, narrow bonded area, hook defect) by metallurgical reaction instead of plastic flow. To enhance the thermomechanical effect of the rotating shoulder, a pin free tool with a large shoulder of 30 mm diameter was used in FSB of 5 mm thick Al/Cu plates in stepped lap configuration with Zn braze. Compared to the case using common tool of 20 mm diameter, it was found that although the intermetallic compound (IMC) layer grew thickly, it was disrupted into particles, and end crack within thick IMC layer was eliminated. As a result, the joint fractured not along interface and the fracture load increased by as much as 2271 N. This work proposed an approach to disrupting continuous IMC into particles by enhancing the mechanical effect of rotating shoulder.     

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。     

Fluxless arc weld-brazing of aluminium alloy to steel

In this work, joining of aluminium alloy AA6061-T6 to Interstitial Free steel using pulsed gas metal arc welding process has been attempted. The effect of different surface conditions of steel (viz, galvanized, galvanealed and uncoated) and gap between the sheets on braze joint formation have been investigated. Galvanized steel surface showed good bead width, joint formation and lap shear strength compared to the other two combinations. Interface gap has not affected the wetting behaviour significantly but presence of a gap of 300 μm or so helped in escape of zinc vapour during the process there by avoiding formation of any crevice or macroporosity in the joint. Features and properties of the joint are characterized by metallography, fractography, energy dispersive spectroscopy (EDS) and lap shear tests. Load carrying capacity of Al-Galvanized steel was highest (222 N/mm of seam length) compared to other combinations, aided by better wetting due to presence of Zn on the surface and minimum porosity due to interfacial gap provided during brazing.     

Seal spot welding of steel and aluminium alloy by resistance spot welding: dissimilar metal joining of steel and aluminium alloy by Zn insertion

This research concerns a dissimilar metal joining of steel and aluminium (Al) alloys by means of zinc (Zn) insertion. The authors propose a joining concept for achieving strong bonded joints between Zn-coated steel and Al alloys. A eutectic reaction between Zn in the Zn coating and uniform Al–Fe intermetallic compound (IMC) layer at the joint interface, leading to a strong bonded joint. The ultimate aim of this research was to apply this joining concept in the resistance spot welding process for manufacturing vehicle bodies. As a practical issue characteristic to joints of dissimilar metals, anticorrosion measures against electrochemical corrosion must be undertaken. If there is moisture near a joint interface of dissimilar metals, electrochemical erosion will progress. Therefore, a sealing function that could prevent moisture intrusion is required. By applying the above-mentioned welding process to a set of metals with thermosetting resin spread in between, we realized seal spot welding, which not only prevented moisture intrusion but also retained high tensile strength. In this research, first, a cyclic corrosion test was performed on the seal spot-welded joint of galvanized (GI) steel, a steel grade widely distributed in Japan, and Al alloy was bonded by seal spot welding, and the following topics are discussed. Complete removal of sealant from the joint interface is the key to realizing the high tensile stress joint, because remaining sealant will lead to reduction in tensile strength. Therefore, heat generation at the interface was monitored by measuring electrical current and potential difference between the two electrodes, and a precise temperature control was performed. Moreover, the bonding process was clarified by stepwise analysis of the joint interface using optical microscopy, and a guideline for producing strong joints was proposed. And finally, a TEM observation also confirmed that the interface structure of the seal spot-welded joint was the same as joints without the resin; a thin and uniform Al–Fe IMC layer was formed and a strong metallurgical bonding was achieved.