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With the wide application of aluminum alloys in automotive, aerospace, and other industries, laser welding has become a critical joining technique for aluminum alloys. In this review, the research and progress in laser welding of wrought aluminum alloys are critically discussed from different perspectives. The primary objective of the review is to understand the influence of welding processes on joint quality and to build up the science base of laser welding for the reliable production of aluminum alloy joints. Two main types of industrial lasers, carbon dioxide (CO2), and neodymium-doped yttrium aluminum garnet (Nd:YAG), are currently applied but special attention is paid to Nd:YAG laser welding of 5000 and 6000 series alloys in the keyhole (deep penetration) mode. In the preceding article of this review (part I), the laser welding processing parameters, including the laser-, process-, and material-related variables and their effects on welding quality, have been examined. In this part of the review, the metallurgical microstructures and main defects encountered in laser welding of aluminum alloys such as porosity, cracking, oxide inclusions, and loss of alloying elements are discussed from the point of view of mechanism of their formation, main influencing factors, and remedy measures. The main mechanical properties such as hardness, tensile and fatigue strength, and formability are also evaluated. 相似文献
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目的 提高铝合金的焊缝抗拉强度,解决铝合金焊接过程中的裂纹缺陷。方法 采用脉冲Nd:YAG激光与半导体激光复合焊接铝合金,先用Nd:YAG激光形成焊接熔池,然后用半导体激光对熔池进行加热保温,获得无裂纹的焊缝,并对焊缝进行抗拉强度测试。结果 与单独的Nd:YAG激光焊接相比,Nd:YAG激光与半导体激光复合焊接的铝合金焊缝抗拉强度提高了50%,达到193MPa,为母材抗拉强度的90%。结论 2束激光的结合延长了熔池的冷却凝固时间,从而有效避免了热裂纹,减少了焊接缺陷,提高了焊接质量。 相似文献
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X. Cao M. Xiao M. Jahazi J. -P. Immarigeon 《Materials and Manufacturing Processes》2005,20(6):987-1004
A continuous wave 4 kW Nd:YAG laser system was used to weld 2-mm butt joints of sand-cast ZE41A-T5 magnesium alloys at a power of 2.5 kW, welding speed of 6.0 m/min, and defocusing distance from - 2 to + 3 mm for the material in the machined surface conditions. It was found that the adjustment of defocusing distance greatly influences the establishment of conduction or keyhole mode welding. Conduction welding is obtained at a power density of 4.0 × 105 W/cm2. Keyhole welding is reached at a threshold irradiance of 1.5 × 106 W/cm2. The fusion zone consists of refined equiaxed grains formed through cellular growth in the Zr-containing magnesium alloys. The partially melted zone is rather narrow, only a few grains wide. No grain growth or coarsening but softening is observed in the heat affected zone (HAZ). The weld defects observed include three main types: imperfect shape, cavities, and weld cracks. The mechanisms of their formations are discussed. In addition, the original cast quality was found to have a significant influence on the formation of defects such as underfill, surface depression, porosity, and burn-through during laser welding. 相似文献
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采用光纤激光-MIG 复合焊和光纤激光焊分别对6009铝合金进行焊接,研究两种焊接方式下焊接接头的成型性、显微组织、拉伸性能、显微硬度、断口形貌的不同。研究表明:激光电弧复合焊的焊接速度是激光焊接的3倍;相比于激光焊,激光电弧复合焊焊缝中心显微组织更加细小;接头的抗拉强度达到母材的63%以上,而激光焊接的抗拉强度仅仅只有母材的38%;显微硬度试验表明:复合焊存在软化区,而激光焊接几乎没有软化区;断口分析表明:复合焊和激光焊的拉伸断口都是典型的韧窝状态,但是复合焊接的韧窝更加均匀。 相似文献
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Nowadays, the Nd:YAG laser has been a promising key tool for joining thin components. In this research, mechanical and microstructural properties of laser welded thin austenitic stainless steel sheets were investigated with experimental investigations, as a function of laser welding parameters. Butt welded joints were made using a Nd:YAG laser in the pulsed wave mode. The appropriate laser welding parameters were found in order to obtain quality and strong weld seam. The pulsed laser seam welding process is controlled by a variety of parameters. We focus on the effects of the several processing parameters on mechanical and microstructural characteristics of joint and weld quality. The aim of this research was to evaluate the influence of these processing parameters on joint strength and microstructure. And also we examined the weldability of stainless steels in butt joint configuration by a pulsed Nd:YAG laser beam. 相似文献
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目的 对0.8 mm厚的Ti6Al4V钛合金和2 mm厚的AA6060铝合金薄板进行脉冲激光焊接,分析异种轻合金激光焊接裂纹产生的机理及界面结合机理。方法 采用扫描电镜、EDS能谱以及显微硬度计等微观表征分析方法,对焊接接头的形貌特征、成分以及显微硬度进行分析,探索焊接接头处裂纹产生的原因。结果 钛/铝脉冲激光焊接性较差,接头存在严重的裂纹缺陷,裂纹多集中在焊缝与铝母材交界处以及焊缝中心区域位置,主要以热裂纹为主;接头焊缝可能存在大量的Ti-Al金属间化合物以及少量未熔的钛,其界面层主要成分推测为层状TiAl和外层锯齿状的TiAl3;接头整个焊缝区域的平均显微硬度为HV0.1420,其硬度水平远远高于焊缝两侧铝合金母材,也高出钛合金母材很多。结论 钛铝金属间化合物使钛铝焊接接头焊缝区脆性增大,另外接头焊缝区存在较大的组织应力、热应力、拉压应力、拘束应力等复杂应力,致使焊缝内存在较严重的裂纹缺陷。 相似文献
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Materials Behavior in Laser Welding of Hardmetals to Steel 总被引:1,自引:0,他引:1
Tool manufacturing industry faces the problem of permanently joining hardmetals to steel holders with high shear strength. The mostly used welding process still is brazing. However, brazed joints have poor lifetimes, mostly when high temperatures are achieved and often break in operation. In a previous study about the ability of CO2 and Nd:YAG lasers to weld hardmetals to steels, it was found that Nd:YAG lasers, working in continuous wave mode, could be used especially for welding hardmetals with Co content around 12%. This article discusses the materials behavior under laser radiation and analyzes the microstructural features observed. 相似文献
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Microstructural and mechanical characterization of laser beam welded AA6056 Al-alloy 总被引:3,自引:0,他引:3
Laser beam welding is considered to be a suitable joining process for high speed, low distortion, and high quality fabrication of aircraft structures manufactured from aluminum alloys, which are mainly preferred due to their favourable properties, such as high strength to weight ratio, ease of forming and high thermal and electrical conductivity. However, the laser beam welding of 6000 series aluminum alloys may exhibit a tendency to solidification cracking, and porosity may be a major problem unless appropriate welding parameters and filler metal are employed.In this study, the microstructural aspects and mechanical properties of laser beam welded new generation aluminum alloy, namely 6056, developed especially for aircraft structures, are investigated. A continuous wave CO2 laser using AlSi12 filler wire was employed. A detailed microstructural examination of the weld region was carried out by Scanning Electron Microscopy (SEM). Standard tensile and microflat tensile specimens extracted from the welded plates were tested at room temperature for the determination of general and local mechanical properties of the welded joints. Extensive microhardness measurements were also conducted. Crack growth mechanisms of the joints produced were also determined by conducting fatigue tests under various stress ratios (i.e., 0.1 ≤ R ≤ 0.7). 相似文献
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目的研究不同工艺参数下高温合金的微激光点焊接头性能。方法利用Nd:YAG激光器对厚度为0.23 mm和0.13 mm的GH4145进行搭接点焊,利用微型拉伸机、金相显微镜、硬度计对接头的物理性能进行测试,并观察组织结构。结果脉宽长度为6.0 ms,输出功率百分比为20%(输出功率16 W)时,最大拉伸剪切力为178.59 N,靠近焊点中心位置两边测试点硬度分别达到HV517和HV506。结论接头表面熔化尺寸、焊接接头的拉伸剪切力和硬度随着激光功率的增大而增大,增大到一定值时停止变化,不同参数下达到不同的最大值,组织无明显规律变化。近表面处出现等轴晶,表面以下至熔合线的显微组织为树状晶。通过激光搭接点焊将两片GH4145连接,接头处拉伸剪切力、硬度均低于母材,功率增大有助于提高接头的抗拉强度。 相似文献
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Aluminum alloy and low-carbon steel are dissimilar metals. In order to obtain a reciprocal comprehensive property in a joint component of aluminum alloy and low-carbon steel, laser welding was used as a novel joining process. Based on the experimental results, the temperature criterion of laser welding for joining of aluminum alloy and low-carbon steel is discussed in this paper. 相似文献
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目的为了解决厚度为0.05 mm的铝合金在激光焊接过程中,材料发生变形导致的焊穿或者虚焊问题。方法采用在下层铝合金材料表面均匀涂覆粘胶剂,将上下2层铝合金材料进行预固定,然后采用激光焊接,形成焊缝。通过控制涂覆粘胶剂的次数,得到胶层厚度为11.2μm,对涂覆粘胶剂的铝合金进行激光焊接实验。结果当激光平均功率为150W,焊接速度为100mm/s,离焦量为2mm时,焊缝剪切强度最大,为124 MPa,达到母材剪切强度的82%。结论通过粘胶剂预固定后,在激光加热过程中,可以很好地克服材料的变形,让上下材料形成熔池,熔池冷却凝固后熔合在一起形成焊缝,可以解决材料发生变形导致的焊穿或者虚焊问题。 相似文献
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Gap-free fibre laser welding of Zn-coated steel on Al alloy for light-weight automotive applications
As a result of new policies related to global warming announced by the European Union, avoiding unnecessary energy waste and reducing environmental pollution levels are becoming a major issue in the automotive industry. Accordingly, the lap welding of Zn-coated steels process, which is commonly used for producing car doors, has been gradually developed to lap welding of Zn-coated steel to light materials, such as Al alloy, Mg alloy and composite materials, in order to effectively reduce the vehicle weight. In certain part of car manufacture, organic glues are used to temporally join the Zn-coated steels and Al alloys before permanent welding takes place. The stability of such temporary joining by glues needs improving. Laser “stitching” or low strength welding could be considered as an alternative. However, challenges exist in joining Zn-coated steel on Al alloy by laser welding, due to significant differences of material properties between the two welding materials. Porosity, spatter and intermetallic brittle phases are readily produced in the weld. In this study, the effects of welding speed, laser power, number of the welding passes and type of shielding gas in gap-free welding of Zn-coated steel on Al alloy were investigated using a 1 kW single mode continuous wave fibre laser. Results show that a weld with higher shear strengths in the laser stitching application and less intermetallic phases could be obtained when nitrogen gas was used as the shielding gas. The corrosion resistance and the surface finish of the weld could be improved in double pass welding, especially when argon gas was used as the shielding gas. 相似文献
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J. P. Bergmann 《Materialwissenschaft und Werkstofftechnik》2004,35(9):543-556
Influence of the oxygen content in the shielding gas on microstructure and mechanical properties of laser welds of titanium and titanium alloys In the present work, a new tool concept for laser welding of titanium in high volume production has been presented and evaluated. Through the innovative application of a six‐layer metal web it is possible to calm the argon gas flow and avoid pernicious turbulences during welding. The integration of the mentioned metal web at the base of an open welding chamber allows the automated welding of highly reactive materials, such as titanium, under atmospheric pressure and inert shielding conditions. The higher density of argon relative to air offers the unique possibility to leave the chamber open on the top, so that a higher degree of flexibility than gas shielding devices for TIG welding, especially for industrial robots, is attained and can be successfully used for industrial mass production. Furthermore this device is important for welding three‐dimensional contours or to shield the regions of overlap (in overlapped joints) where shielding gas trailers are unsuccessful. By means of the presented gas shielding procedure and a modern laser welding process such as Nd:YAG laser welding, systematic investigations on the effect of oxygen on the microstructure as well as on the mechanical properties of reference bead‐on‐plate weldments could be performed for the first time. As a result of these welding trials it can be concluded that in order to avoid discolorations and hardness increase, lower restrictions to the purity of the shielding gas, in comparison to TIG welding condition, can be allowed. The maximum tolerable value of oxygen in the welding atmosphere was found to be approximately 1000 ppm for laser welding. On the contrary the maximum value for TIG welding is about 30 ppm. Further investigations on the microstructural and mechanical properties of the joints confirm that the optical quality assurance criteria for TIG welding due to the standards of aircraft construction transferable to Nd:YAG welding are. 相似文献
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Liang Gongying Eric.T.T.Wong H.C.Man Xi''''an Jiaotong UniversityXi''''an The Hong Kong PolytechnicUniversity Hong Kong 《国际设备工程与管理》1997,(2)
AComparisonofLaserCladdingNi-basedCoatingonanAluminiumAloywithCO2LaserandNd:YAGLaserLiangGongyingEric.T.T.WongH.C.ManXi’anJia... 相似文献
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