机械类外文翻译【FY121】C型搅拌摩擦焊的现状与发展【中英文WORD】【中文5200字】
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毕业设计（ 外文翻译 ） 题 目： C 型搅拌摩擦焊机机械结构设计 系 别 ： 航空工程系 专 业名称 ： 机械设计制造及其自动化 班级学号 ： 078105337 学生姓名 ： 袁 振 东 指导教师 ： 张 晓 荣 二 O 一一 年 六 月 nts C 型搅拌摩擦焊的现状与发展 1 前言 1991 年 ,英国焊接研究所（ The Welding Institute-TWI）发明了搅拌摩擦焊（ Friction Stir Welding-FSW），这项杰出的焊接技术发明正在为世界制造技术的进步做出贡献。 在国外 ,搅拌摩擦焊已经在诸多制造领域达到规模化、工业化的应用水平。如在船舶制造领域，在 1996 年搅拌摩擦焊就在挪威 MARINE 公司成功地应用在铝合金快速舰船的甲板、侧板等结构件的流水线制造。在轨道车辆制造领域，日本HITACHI 公司首先于 1997 年将搅拌摩擦焊技术 应用于列车车体的快速低成本制造，成功实现了大壁板铝合金型材的工业化制造。在世界宇航制造领域，搅拌摩擦焊已经成功代替熔焊实现了大型空间运载工具如运载火箭和航天飞机等的大型高强铝合金燃料贮箱的制造，波音公司的 DELTA II 型和 IV 型火箭已经全部实现了搅拌摩擦焊制造，并于 1999 年首次成功发射升空。 2000 年世界汽车工业，如美国 TOWER 汽车公司等就利用搅拌摩擦焊实现了汽车悬挂支架、轻合金车轮、防撞缓冲器、发动机安装支架以及铝合金车身的焊接。 2002 年 8 月，美国月蚀航空公司利用 FSW 技术研制出了全搅拌摩擦焊轻型 商用飞机，并且首次试飞成功。 2 搅拌摩擦焊的技术特点 搅拌摩擦焊作为一项新型焊接方法，用很短的时间就完成了从发明到工业化应用的历程。目前 ,在国际上还没有针对搅拌摩擦焊公布的统一技术术语标准，在搅拌摩擦焊专利许可协会的影响下，业界已经对搅拌摩擦焊方法中所涉及到的通用技术术语进行了定义和认可。 下 图示出了搅拌摩擦焊所用到的主要描述性术语。 nts 搅拌摩擦焊是一种在机械力和摩擦热作用下的固相连接方法。如图 1 所示，搅拌摩擦焊过程中，一个柱形带特殊轴肩和针凸的搅拌头旋转着缓慢插入被焊接工件，搅拌头和被焊接材料之间的 摩擦剪切阻力产生了摩擦热，使搅拌头邻近区域的材料热塑化（焊接温度一般不会达到和超过被焊接材料的熔点），当搅拌头旋转着向前移动时，热塑化的金属材料从搅拌头的前沿向后沿转移，并且在搅拌头轴肩与工件表层摩擦产热和锻压共同作用下，形成致密固相连接接头。 搅拌摩擦焊具有适合于自动化和机器人操作的诸多优点，对于有色金属材料（如铝、铜、镁、锌等）的连接 ,在焊接方法、接头力学性能和生产效率上具有其他焊接方法无可比拟的优越性，它是一种高效、节能、环保型的新型连接技术。 但是搅拌摩擦焊也有其局限性，例如：焊缝末尾通常有匙孔存在 （目前已可以实现无孔焊接）；焊接时的机械力较大，需要焊接设备具有很好的刚性；与弧焊相比 ,缺少焊接操作的柔性；不能实现添丝焊接。 搅拌摩擦焊对材料的适应性很强，几乎可以焊接所有类型的铝合金材料，由于搅拌摩擦焊接过程较低的焊接温度和较小的热输入，一般搅拌摩擦焊接头具有变形小、接头性能优异等特点 ;可以焊接目前熔焊“不能焊接”和所谓“难焊”的金属材料如： Al-Cu(2xxx 系列 ) 、 Al-Zn(7xxx 系列 )和 Al-Li(如 8090、 2090 和2195 铝合金 )等铝合金。 另外，搅拌摩擦焊对于镁合金、锌合金、铜合 金、铅合金以及铝基复合材料等材料的板状对接或搭接的连接也是优先选择的焊接方法；目前，搅拌摩擦焊还成功地实现了不锈钢、钛合金甚至高温合金的优质连接。 搅拌摩擦焊可以较容易实现异种材料的连接，例如铝合金和不锈钢的搅拌摩擦焊接，利用搅拌摩擦焊可以较方便的实现铝钢板材之间的连接和铜铝复合焊nts 接接头。 3 搅拌摩擦焊在国外的发展 搅拌摩擦焊作为一种轻合金材料连接的优选焊接技术，已经从技术研究，迈向高层次的工程化和工业化应用阶段 ,形成了一个新的产业 : 搅拌摩擦焊设备的制造、搅拌摩擦焊产品的加工 .如在美国的宇航制造工 业、北欧的船舶制造工业、日本的高速列车制造等制造领域，搅拌摩擦焊得到了广泛的应用 ,均已形成新兴产业。 4 激光辅助搅拌摩擦焊 激光辅助搅拌摩擦焊（ LAFSW）是一种新改进的搅拌摩擦焊，搅拌摩擦焊是近 10 年开发的工艺。 在搅拌摩擦焊里，焊接热能是来自工具和工件之间摩擦热量。由于这种工艺需要相对大的力，因此，在搅拌摩擦焊中使用的设备笨重且昂贵。激光辅助搅拌摩擦焊用激光能源加热工件，而搅拌头的主要作用是搅拌和连接工件 2 部分。由于这种原因，激光辅助搅拌摩擦焊是一种相对简单和廉价的方法。 为了克服搅拌摩擦焊中存在的 不足，如（ 1）装夹焊接工件的夹具较大，需要很大的力向前移动焊接工具，焊接工具磨损率相对高；（ 2）用感应线圈方法加热不能保证正确的位置、焊接搅拌头和夹具装置都受到加热感应线圈的影响及用感应线圈作媒介加热及仅适用于导体材料，并不能用于其他非金属和非导体材料。人们开发了的激光辅助搅拌摩擦焊 。这种方法由通用铣床和 Nd： YAG 激光器改造成的。激光能源在旋转搅拌头前面有限范围内预热工件。这样，旋转的搅拌头前面的工件体积、塑性增加（插图 1）。然后，采用与普通 FSW 工艺一样的方法连接工件。旋转工具前面的高温软化了工件，并 且可以不用强大夹具装夹就能够保证连接。向前移动焊接工具只需很小的力，所以减少了磨损。对于激光能源这种工艺的优点还有焊接能力较高，焊接中不会引起过多的磨损。商业用的激光器，具有很精确地激光直径控制装置，因此，控制工件的受热区域和激光源到达工件的数量，并且保持系统的其他部位的受热是比较容易的。 目前 激光辅助搅拌摩擦焊的焊接工艺已经被证明。激光能预热工件的使用标nts 志着在焊接工具和工件中需要提供较大的力的降低，用这种改进的方法简化了使用，因此使用经济的焊接方法已成为可能。另外，较高的焊接速度在改进中获得了较好的效 益。 5 搅拌摩擦焊铸铝的高效连接技术 针对 ZL114A 合金广泛应用，中国搅拌摩擦焊中心对该材料的搅拌摩擦焊工艺适应性进行了开发， 试验数据表明，该材料的搅拌摩擦焊工艺适应性良好，接头抗拉强度达到了母材的 91%，接头力学综合性能优于电子束等熔焊方法。 ZL114A 合金（旧牌号为 ZAlSi7Mg1A），是在 ZL101A 合金基础上增加 Mg 元素的含量发展起来的 Al-Si-Mg 系高强度铸造铝合金。它既具有优良的铸造工艺性能，又具有较 ZL101A 合金更高的力学性能。由于其优越特性，在航空航天制造业中，广泛用于 制造重要部位的大型薄壁结构件。 ZL114A 合金应用前景广阔，产生了对材料高效连接技术的迫切需求。因采用熔焊方法，热输入量较大，焊接变形大，难以满足薄壁件精度要求；并且焊缝易出现气孔、夹渣、未焊透、烧穿、裂纹等缺陷，缺陷率高；而且焊前焊后处理工序较繁琐。 搅拌摩擦焊是一种新兴的金属固相连接技术，金属在焊接过程中不熔化，热输入量小；焊缝的连接是在金属受挤压的状态下完成的，焊接接头不会产生熔化焊焊接接头的气孔和裂纹等一类缺陷，焊缝缺陷少；搅拌摩擦焊类似于机械加工过程，容易实现自动化控制，而且没有熔化焊中的电 压，电流，强光，金属粉尘等现象，工作环境环保清洁。最重要的是，搅拌摩擦焊接头的力学性能优于熔焊接头。试验数据表明焊接接头的抗拉强度达到了母材的 91，试样延伸率达到了 2.5，接头组织晶粒细化、均匀而致密，消除了母材的铸造缺陷。 ZL114A 母材与焊接接头微观组织对比，可观察到焊核区微观组织是无方向性的、细小的等轴晶粒，母材区为粗大的树枝状铸造组织。搅拌摩擦焊是一种区别于熔化焊和机械连接的新型焊接技术，基于其技术优势，在航空制造业中的应用具有巨大的潜在性，为各种轻质合金高效连接，提供了解决途径和方法。 6 搅拌摩擦焊接在运载火箭上的应用 运载火箭贮箱常用的材料是比强度高、比刚度高的铝合金，如 2014， 2219和 7075 铝合金。现在，运载火箭贮箱又采用性能更好的 2195 铝锂合金。在航天产品中，特别是在制 造运载火箭贮箱中，焊接工艺是一项关键的制造技术。熔焊技术如气体钨极电弧焊（ GTAW ）和气体金属电弧焊（ GMAW）自 20 世纪nts 50 年代起，在雷神、宇宙神、大力神、土星和德尔它 系列运载火箭贮箱的制造中使用了几十年，从焊接设备、焊接材料、焊接工艺等方面作了大量的研究工 作，满足了焊接质量的需要。同时，为了提高焊 接质量和降低成本， 20 世纪 80 年代美国又采 用了变极性等离子弧焊（ VPPA）焊机，并配备了先进的计算机控制系统，代替了 GTAW 和 GMAW ，焊接了 2219-T87 铝合金制的航天飞机外贮箱，使焊接工艺在贮箱的制造中向前迈进了一 大步。迄今为止，虽然焊接质量有所提高，焊接时间有所缩短，但仍不能彻底解决焊缝及近缝区的裂纹和减少焊接气孔等缺陷问题。 1991 年英国剑桥大学焊接研究所（ TWI）发明了搅 拌摩擦焊接(FSW)。这种焊接技术焊接的铝合金变形小、冶金和力学性能高、成本低和焊接时间短。 挪威在世界上最早用 FSW 焊接技术焊接过 6 mm16 m2 的 6068-T6 铝合金船面板和 20 m 长的铝合金制的快艇，焊接总长达 10 000 m。瑞士也研制出 FSW 焊机。为了加速 FSW 焊 接技术在工业上的应用， 1995 年国际合作公司赞助了一项计划，由 TWI 研究所牵头继续研究 FSW，并用 FSW 焊接 2000 系（ ）、5000 系（ ）、 6000 系（ ）等铝合金，并均获得满意的焊接质量。 TWI 研究所、美国爱迪生焊接研究所（ EWI）等部门，除了研究用 FSW 焊接铝合金外，还研究用它焊接黑色金属及其它金属。美国的航空 航天工业部门对F SW 开展了更多的应用性研究，如洛 马公司、波音公司投入了大量的研制经费，仅花在 FSW 焊接工艺和设备研制上的费用就达 1500 万美元，成功地焊接了德尔它 的运载火箭贮箱 。 由于 FSW 是在比被焊合金材料熔点温度低的条件下完成的固态连接，所以金属材料没有熔化，焊接收缩变形小和力学性能损失低，与传统的 GMAW 和GTAW 熔焊技术焊接铝合金相比，有着突出的优点： a）不需要氩、氦保护气体和填充材料，焊接时不需要控制焊接电流和电弧电压参数，节省了大量材料的消耗。 b）焊前不需要对被焊接材料和焊丝仔 细清理、酸洗、打磨和烘干等，不必对被焊接材料机械加工开剖口，节省了许多操作时间。 c）焊工不要求有高的操作技术。 d）焊接能量效率高，单层焊接 6000 系铝合金可达 12.7 mm 厚度，因此适合于自动 化生产。 e）不存在铝合金焊接主要缺陷，即裂纹敏感性问题，因此，容易焊接难以焊nts 接的铝合金材料，如 7075 铝合金。 f）由于 FSW 可以保持合金的冶金性能，所以可焊接金属基复合材料和快速凝固材料。 g）采用最佳的焊接参数，可以获得无气孔的焊缝。 h）可以焊接异种金属，如铸造和挤压、铸造和锻造材料等。 i）用 FSW 可 以焊接许多通常不能够焊接的长而大的横截面零件。 J）焊接大尺寸挤压件变形很小。 k）焊接前工件装配要求低，待焊接表面根部不必紧配合，根部装配间隙允许公差低， 1.6 mm 厚薄板根部装配间隙为 0.2 mm， 12.7 mm 厚板为 1.25mm。 FSW 是一项适合于焊接铝合金的新技术。因为它是固态焊接，与熔焊铝合金技术相比，具有 3 个主要优点： a）固态连接消除了与熔焊有关的裂纹，即液化或固化裂纹。在最佳焊接条件下完全消除气孔。 b）不存在焊缝金属蒸发产生的合金元素损失，焊缝合金元素得到保存，因此焊接质量得到保证。 c）由于焊接工具对材料产生的碾压、搅拌和锻造作用，可得到比基体金属更为细小的再结晶组织，焊缝金属强度超过了焊接热影响区材料的强度。 用于运载火箭贮箱的材料 2014-T6 高强度铝合金（中国牌号为 LD10）是比较难焊接的金属材料，其焊接热裂纹倾向性高，焊接接头强度系数为 0.5 左右，塑性不高，延伸率仅 2% 3 %，补焊性能差。 FSW 焊接后的接头弯曲试样证明：接头塑性明显提高，弯曲角达 180，拉 伸试样均断在焊缝金属外的热影响区。2014-O 状态拉伸试样破坏均断在基体金属。与熔焊接头相比， FSW 焊接接头 的抗拉 强度高 30% 50%，焊接接头的强度系数达 0.7，断裂韧性提高，疲劳性能与铆接 的相同。 2519-T87 高强度铝合金有优异的冲击性能，用于海军先进的水陆两用攻击型战车，但用普通熔焊时，焊接接头塑性低，不能通过必须的冲击验收试验，经 FSW 焊接后的焊接接头比熔焊接头塑性提高，强度相同，成功地通过了弹道冲击试验。 2195-T8 铝锂合 金采用 FSW 焊接，焊接接头力学性能比VPPA 焊接接头力学性能高得多 。 FSW 发展很快，已有 10 年。自从 1995 年以来，欧洲、美国和日本等一些国家对 FSW 开展了应用性研究，特别是美国航 空航天工业部门高度重视该技术，并用它 成功地焊接了以往难以焊接的 7075 铝合金低温燃料贮箱，其力学性能很nts 好。 5454 铝合金焊接后有很好的抗腐蚀性。 当前各国都在研究不同铝合金，不同接头形状的焊接 ， 着手建立材料焊接力学性能数据库，建立飞机和航天工业用铝合金焊接标准，并将 FSW 应用扩大到汽车、造船 、铁路 、建筑、压力容器等部门。同时研究熔点高的钛合金材料，包括金属基材料在内的泡沫铝合金材料的焊接。 FSW 焊接主要依靠设备完成，研究的重点是夹持器和特型指棒。研究证明：工具的形状决定了焊缝金属塑性加热、热塑性 材料的流动和锻造形式；夹持器的尺寸决定了焊缝 的尺寸、焊接速度；工具材料决定了摩擦加热速度、夹持器的强度、工件温度；所以，夹持器决定了焊缝的最终质量。在各国的专利中，为了焊接出最好的力学性能和冶金性能、完全 无气孔、光滑表面的焊缝，对各种各样的特型指棒的形状分别作了研究；对圆柱形夹持器的直径 2rs、几何形状、焊接速度 、向下的作用力 F 以及 焊接材料厚度 W 的最佳配合作了研究，得出了以下结论： FSW 是一种最新的非常适合于焊接铝合金的工艺技术，具有焊接变形小、质量高和成本低等优点。虽然发展时间不长，在运载火箭贮 箱制造等领域已经获得应用，并在进一步 扩大。由于这种焊接工艺在航空航天工业部门的重要性，又极具潜力，目前关键性的焊接规范参数和工具技术还处于保密阶段。我国应要尽早开展 FSW 在航天工业上的研究，用于高强度铝合金制造的产品中。 nts FSW-C Current Status and Development 1 Preface In 1991, the British Welding Research Institute (The Welding Institute-TWI) invented the FSW (Friction Stir Welding-FSW), the invention is excellent welding technology advances in manufacturing technology for the world to contribute. At Abroad, friction stir welding has been achieved in many large-scale manufacturing, the application level of industrialization. Areas such as shipbuilding, in 1996, friction stir welding in Norway MARINE successfully applied to fast ship aluminum deck, side panels and other structural parts of the assembly line manufacturing. In the rail equipment manufacturing field, the first Japanese company in 1997 HITACHI friction stir welding technology in the train body fast low-cost manufacturing, successful implementation of a large panel of industrial aluminum profiles manufacturing. Aerospace manufacturing in the world, instead of friction stir welding has been successfully implemented large-scale fusion, such as launch vehicles and space launch vehicles and other large-scale space shuttle fuel tank manufacturing high strength aluminum, Boeing DELTA II rocket type and IV have all been Friction stir welding manufacturing implements, and in 1999 the first successful launch. 2000 world automotive industry, automobile companies, such as the U.S. TOWER on the use of friction stir welding to achieve the car hanging bracket, light alloy wheels, anti-collision buffer, engine mounting bracket and the aluminum body of the weld. August 2002, the United States Air eclipse technology developed by the entire FSW FSW light commercial aircraft, and the first successful test flight. 2 The technical characteristics of friction stir welding The technical characteristics of friction stir welding friction stir welding as a new welding method, using a very short time to complete the invention to the industrial application from the course. At present, no international publication for the unity of friction stir welding technology terminology standards, patent licensing in the friction stir welding under the influence of the Association, the industry has been friction stir welding method of the involved technical terms are defined and recognized. The following figure shows the use of friction stir welding of the main descriptive terms. FSW is a frictional heat in the mechanical and solid under the action of the connection method. Shown in Figure 1, friction stir welding process, a cylindrical shaft with a special convex shoulders and pin head spinning slowly stirred into the workpiece to be welded, welding materials mixing head and is the shear resistance of the friction between the friction heat generated , So that mixing the first neighborhood of thermal plastics (welding temperature normally does not reach and exceed the melting point of welding materials), when the mixing head spinning move forward, the hot plasticized metal back from the forefront of the pin Along the transfer, and in nts the mixing head shoulder and the workpiece surface friction and heat and forging together, form a dense solid connectors FSW with automation and robotics operations for the many advantages, for non-ferrous materials (such as aluminum, copper, magnesium, zinc, etc.) connection, welding, mechanical properties of joints and productivity that has no other welding methods Compare the advantages, it is an efficient, energy saving, environment-friendly new connection technology. However, friction stir welding also has its limitations, such as: weld at the end there is usually a key hole (hole-free now for welding); large mechanical force during soldering, welding equipment need to have good rigidity; and arc phase Ratio, the lack of flexible welding operations; can not be achieved filler metal welding. FSW adaptability of materials, almost all types of aluminum alloy welding, friction stir welding process because the lower temperature and smaller welding heat input, the general deformation of friction stir welding head with a small, joint performance And so on; to fusion welding current can not be welded, and so-called hard to weld the metal materials such as: Al-Cu (2xxx series), Al-Zn (7xxx series) and Al-Li (such as 8090,2090 and 2195 aluminum Alloy) and other aluminum alloy. In addition, friction stir welding for magnesium alloy, zinc alloy, copper alloy, lead alloys, and aluminum matrix composites and other materials, the connection plate butt or lap welding method is preferred; present, friction stir welding has also successfully achieved Stainless steel, titanium or high-temperature alloys high-quality connections. Fsw of dissimilar materials can be more easily achieved the connection, such as aluminum and stainless steel by friction stir welding, the use of friction stir welding of aluminum can be more easily achieved - the connection between steel plates and copper and aluminum composite joints. 3 FSW development abroad FSW in the development of friction stir welding abroad as a preferred light alloy welded connection technology, has moved from technical studies, into a high level of engineering and industrial application stage, the formation of a new industry: friction stir welding equipment Manufacturing, processing and friction stir welding products. If the aerospace manufacturing industry in the United States, the Nordic shipbuilding industries, manufacturing, and other high-speed train in Japan manufacturing, friction stir welding has been widely used, have been the formation of new industries. 4 Laser assisted friction stir welding Laser assisted friction stir welding (LAFSW) is a new and improved friction stir welding, friction stir welding is a technique developed nearly 10 years. In friction stir welding, the welding heat from the heat of friction between tool and workpiece. Since this process requires a relatively large force, therefore, the use of friction stir welding equipment cumbersome and expensive. Laser assisted friction stir welding using laser energy heating the workpiece, and the pin connecting the main nts role is to stir and the workpiece 2. For this reason, laser assisted friction stir welding is a relatively simple and inexpensive methods. In order to overcome the friction stir welding deficiencies, such as (1) welding the workpiece clamping fixture larger force to move forward requires a lot of welding tools, welding tool wear rate is relatively high; (2) the method of induction heating coil is not To ensure the correct position, welding mixing head and fixtures are subject to the impact of the induction coil and heated by induction coil for heating and only for the media conductor material, and can not be used for other non-metallic and non-conductive material. It has developed a laser assisted friction stir welding. This approach by the general milling and Nd: YAG laser converted into a. Laser energy in the rotating mixing head warm in front of the workpiece within a limited range. In this way, rotating the workpiece in front of the volume mixing head, the plastic increase (Figure 1). Then, the FSW process and ordinary connection the same way as the workpiece. Softening the front rotary tool workpiece, and clamping fixture may not be able to guarantee a strong connection. Welding tools to move forward only a small force, so a reduction of wear and tear. The advantages of this technology of laser energy also welding with higher welding does not cause excessive wear and tear. Commercial use of the laser, the laser has a very precise diameter control device, therefore, control of the workpiece and the laser heat source to reach the regional number of jobs and keep other parts of the heating system is relatively easy. Currently laser assisted friction stir welding of the welding process has been proven. Preheat the workpiece to the use of laser marks in the welding tool and the workpiece in the need to provide a larger reduction in force, with this improved method simplifies the use of, the use of economical welding method is possible. In addition, the higher the welding speed to obtain a better in improving the efficiency. 5 FSW - Aluminum high-connectivity ZL114A alloy widely used for the Chinese Center for friction stir welding of the friction stir welding process of adaptation to the development, test data show that the friction stir welding process well adapted, the joint tensile strength of the base metal 91 %, overall performance is better than the mechanical joints such as electron beam welding methods. ZL114A alloy (the old grade is ZAlSi7Mg1A), is based on the increase in ZL101A Mg alloy element content developed Al-Si-Mg system high strength cast aluminum alloy. It has excellent casting properties, but also has higher than the mechanical properties of ZL101A alloy. Because of its superior characteristics, in the aerospace manufacturing industry, the important parts are widely used in the manufacture of large thin-walled structure. ZL114A alloy and promising, resulting in high connectivity for the urgent material needs. By using fusion method, a large amount of heat input, welding deformation, difficult to meet the requirements of thin-walled precision parts; and prone to weld porosity, slag, lack of penetration, burn, cracks and other defects, defect rate; and treatment before welding after welding process more cumbersome. Friction stir welding is a new solid metal connection technique, the metal is not melted during the welding process, a nts small amount of heat input; weld metal connection is accomplished by squeezing the state, the welded joint does not produce fusion welding pores and cracks, welded joints, and other similar defects, fewer weld defects; similar mechanical friction stir welding process, easy automation, and does not melt welding voltage, current, light, metal dust and other phenomena, the work environment environmental cleaning. The most important is that friction stir welding is superior to the mechanical properties of welded joints. Experimental data show that the tensile strength of welded joints for 91% of the base material, the specimen extension rate of 2.5%, joints grain refinement, uniform and compact, eliminating the base metal casting defects. ZL114A base metal and welded joint microstructure compared to the weld nugget zone can be observed microstructure is no direction, and small equiaxed grains, base metal as a coarse dendritic cast structure. Friction stir welding is a welding and mechanical connections different from the melting of new welding technology, based on its technical advantages in the aviation industry in the application of great potential, for a variety of light alloys and efficient connectivity, and provide a solution methods. 6 FSW applications in launch vehicles Launch vehicle tanks commonly used material is high specific strength and stiffness than aluminum, such as 2014,2219 and 7075 aluminum alloy. Now, the launch vehicle performance and better use of the tank and aluminum-lithium alloy 2195. Aerospace products, especially in the manufacturing launch vehicle tank, the welding process is a key manufacturing technology. Welding techniques such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) 50 years since the 20th century onwards, Thor, Atlas, Titan, Saturn and the Delta series of launch vehicles used in the manufacture of tanks Decades, from welding equipment, welding materials, welding technology has done a lot of research work to meet the needs of the welding quality. Meanwhile, in order to improve the welding quality and reduce costs, the 20th century, the United States has adopted 80 of variable polarity plasma arc welding (VPPA) welder, and equipped with advanced computer control system to replace the GTAW and GMAW, welded 2219-T87 Space shuttle external tank, aluminum alloy, so that the welding process in the manufacture of the tank a big step forward. So far, though improved weld quality, weld time has been shortened, but still not completely solve the weld and the crack near the weld area and reduce the porosity and other weld defects. University of Cambridge in 1991, Welding Institute (TWI) the invention of friction stir welding (FSW). The welding deformation of aluminum alloy welding, metallurgical and mechanical properties, low cost and welding time is short. Norway first in the world with FSW welding technique had 6 mm 16 m2 of 6068-T6 aluminum panels and 20 m long ships boats, aluminum alloy, welding total length of 10 000 m. Switzerland has developed a FSW welding machine. FSW welding technology in order to accelerate the industrial application, in 1995 co-sponsored an international program led by the TWI Institute continue to study the FSW, and with the Department of FSW welded 2000 (Al Cu), 5000 series (Al Mg), 6000 (Al Mg Si) and other aluminum alloy, and welding quality are nts satisfactory. TWI Institute, United States Edison Welding Institute (EWI) and other departments, in addition to welded aluminum alloy FSW for research, but also use it to study welding ferrous metals and other metals. U.S. aerospace industry sector F SW carried out more applied research, such as the Luo Martin, Boeing invested a lot of development costs, only spent FSW welding process and equipment development and the costs amounted to $ 15,000,000 The successful welding of the Delta launch vehicles tank. Since FSW is welded alloy melting point than the low temperature solid-state under the conditions of complete connection, so there is no melting of metallic materials, welding and mechanical properties of small shrinkage loss is low, and the fusion of traditional GMAW and GTAW welding aluminum technology compared to Has outstanding advantages: a) do not need to argon, helium, shielding gas and filler material, welding need to control the welding current and arc voltage parameters, saving a lot of material consumption. b) do not need to be before welding wire welding material and careful cleaning, pickling, polishing and drying, do not have to be welded material machining profile mouth open and save a lot of operating time. c) does not require a high welding technique. d) welding energy efficient, single-layer welding 6000 series aluminum alloys up to 12.7 mm thickness, and therefore suitable for automated production. e) there is no major defects in aluminum alloy welding, the crack sensitivity of the issue, therefore, easy to difficult welding of aluminum alloy welding materials, such as 7075 aluminum alloy. f) Since FSW metallurgical properties of the alloy can be maintained, so I can weld metal matrix composites and rapidly solidified materials. g) to adopt the best welding parameters, pore-free weld can be obtained. h) can weld dissimilar metals, such as casting and extrusion, casting and forging materials. i) can be welded by FSW welding many often can not be a long and large cross-section parts. J) Large size extrusion welding deformation is small. k) the workpiece before welding, assembly requirements low, the surface of the roots do not have to be welded tight fit, the root of the assembly gap tolerances low, 1.6 mm thickness of the plate assembly space for the roots of 0.2 mm, 12.7 mm thick as 1.25mm. FSW is a welding aluminum is suitable for new technologies. Because it is a solid-state welding technology and welding aluminum, compared with three main advantages: a) elimination of solid-state connection with welding the cracks, that is, liquefied or solidified cracks. Optimum welding conditions in the complete elimination of porosity. b) there is no weld metal evaporation loss of alloying elements, the weld alloy nts elements are preserved, so the welding quality is guaranteed. c) the welding tool on material produced by crushing, stirring and forging the role of the base metal can be obtained more than fine recrystallized weld metal strength over the HAZ material strength. The material used for launch vehicle tank with high-strength aluminum alloy 2014-T6 (China grades for the LD10) is more difficult to weld metal material, the welding hot cracking tendency of high, welded joint strength factor of about 0.5, the plastic is not high, extending rate of 2% to 3%, welding performance is poor. FSW joints welded bend specimens after the proof: the plastic joints significantly improved, bending angle of 180 , tensile specimens were broken in the weld metal beyond the heat affected zone. 2014-O state of tensile specimens were broken in the destruction of the base metal. Compared with the welded joints, FSW tensile strength of welded joints and 30% to 50%, welded joint strength factor of 0.7, fracture toughness, fatigue performance and riveting of the same. High-strength aluminum alloy 2519-T87 has excellent impact properties, for the Navys amphibious attack tanks advanced, but with ordinary welding, the welded joints of low plasticity, the impact can not be acceptance test, after welding by the FSW than the welded joints of welded joints to improve plasticity, strength the same, successfully passed ballistic impact test. 2195-T8 Al-Li alloy by FS
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