Ta/Ni/Mo异种薄板激光熔钎焊正交试验探究

目的探究Ta/Mo异种薄板激光熔钎焊的最佳焊接工艺参数。方法设计正交试验方案,得出理论最优工艺参数。采用SL-08型Nd:YAG脉冲激光焊机对薄板完成焊接得到焊接接头;通过微机控制电子万能试验机测试焊接接头的抗拉强度;通过显微硬度计测量焊接接头显微硬度;通过OM测试方法观察焊缝组织。并通过焊接接头的性能对得出的最优工艺参数进行验证。结果在最佳焊接工艺参数下,接头的最大平均抗拉强度为230 MPa,接近Ta母材的抗拉强度,拉伸试样断裂发生在近Ta热影响区;焊缝表面连续,可看到清晰的鱼鳞纹,焊缝背面宽度均匀,焊缝成形良好;焊缝中心区域出现了针状共晶组织,热影响区的晶粒都呈现不同程度的长大现象;形成接头的焊缝区硬度最高,钼母材次之,钽母材最小。结论通过正交试验得出的最优工艺参数是准确的,Ta/Mo异种薄板最佳焊接工艺参数为:激光功率P为20.8 W(激光功率百分比为26%),脉宽T为5.5 ms,脉冲频率f为4.0 Hz。     

超薄不锈钢片的微激光焊接工艺研究

采用微型脉冲激光实现了0.2mm厚321不锈钢片的对接焊,并通过正交优化设计对工艺参数进行了优化,研究了工艺参数对焊接接头微观形貌及组织的影响。结果表明,焊接接头获得最大抗拉力的最优工艺参数是脉冲功率百分比为15、脉冲频率为5Hz、脉冲宽度为2.1ms,此时焊接接头的承载能力达到母材的95%。当微激光焊的脉冲能量过大时会产生热量的积累、导致焊缝发生烧穿,当脉冲宽度较小时激光脉冲的熔透能力较弱、导致焊缝未焊透,这两者都会导致焊接接头的承载能力较差。承载能力较高的焊接接头其显微组织由焊缝中心区的等轴晶和焊缝边缘细小的柱状晶组成。     

Optimization of weld bead geometry of laser welded ANSI 304 austenitic stainless steel using grey-based Taguchi method

This paper investigates the quality characteristics of the welding geometry of the laser welding process for the ANSI 304 austenitic stainless steel, with the use of a pulsed Nd:YAG laser welding system. Laser welding of 2 mm thick ANSI 304 stainless steel is performed at three different levels of three factors, i. e., peak power, welding speed and pulse duration. In this study, a multi-response optimization problem is developed to achieve weld bead geometry with full penetration as well as a narrow bead width and minimum crater. Grey relational analysis based on Taguchi orthogonal array is used to present an effective approach for the optimization of laser welding process parameters. Regression equations between the welding parameters and the bead dimensions for laser welded austenitic stainless steels are developed, which are used in predicting the penetration, width and crater. Finally, the equations are tested for values different from the levels of the parameters in the orthogonal array. It will be beneficial to engineers for continuous improvement in laser welded product quality.     

Nd:YAG激光与半导体激光复合焊接对铝合金焊缝组织和性能的影响

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。     

钛/铝异种合金脉冲激光焊接接头裂纹产生机理

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。     

Optimization of deep penetration laser welding of thick stainless steel with a 10 kW fiber laser

Deep penetration laser welding of 12 mm thick stainless steel plates was conducted using a 10 kW high-power fiber laser. The effect of the processing parameters on the weld bead geometry was examined, and the microstructure and mechanical properties of the optimal joint were investigated. The results show that the focal position is a key parameter in high-power fiber laser welding of thick plates. There is a critical range of welding speed for achieving good full penetration joint. The type of top shielding gas influences the weld depth. The application of a bottom shielding gas improves the stability of the entire welding process and yields good weld appearances at both the top and bottom surfaces. The maximum tensile stress of the joint is 809 MPa. The joint fails at the base metal far from the weld seam with a typical cup–cone-shaped fracture surface. The excellent welding appearance and mechanical properties indicate that high-power fiber laser welding of a 304 stainless steel thick plate is feasible.     

Research and Progress in Laser Welding of Wrought Aluminum Alloys. I. Laser Welding Processes

With the wide application of Al 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 Al alloys have been critically discussed from different perspectives. The primary objective of this 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 Al 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 this part of the review, the main laser welding processing parameters including the laser-, process-, and material-related variables and their effects on weld quality are examined. In part II of this article in this journal, the metallurgical microstructures and main defects encountered in laser welding of Al 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. In part II, the main mechanical properties such as hardness, tensile, and fatigue strength and formability are also discussed.     

厚度为0.05 mm的316不锈钢激光焊接工艺

目的 研究0.05 mm厚不锈钢的最佳激光焊接参数,以便对实际生产进行指导.方法 采用IPG公司的连续光纤激光器对厚度为0.05 mm的316不锈钢进行连续焊接.首先,对焊接夹具的夹持间距进行研究;其次,通过设置焊缝轨迹导出线解决轨迹末尾的弧坑问题;最后,对激光功率、焊接速度及离焦量进行正交试验.结果 当激光功率为70...     

固溶处理对304/Q245R焊接接头组织及性能的影响

为研究固溶处理对304奥氏体不锈钢和Q245R碳钢异种金属焊接接头显微组织及性能的影响,采用E309-16奥氏体不锈钢焊丝对6 mm厚的304/Q245R板材进行手工电弧焊,焊后使用箱式电阻炉对焊接接头进行固溶处理,对焊接接头进行显微组织观察和力学性能测试.结果表明:相对于固溶处理前,固溶处理后的接头焊缝组织为灰色奥氏体和黑色铁素体,枝晶偏析程度明显降低,Cr、Ni等合金元素分布较为均匀;焊缝和碳钢侧热影响区硬度值均有所提高,最高硬度值为304.59 HV,出现在焊缝位置;接头抗拉强度较高,达570 MPa,拉伸断裂发生在母材Q245R碳钢部位.另外,对焊缝进行XRD测定,未检测到不利于接头性能的相,这表明固溶处理后的异种金属接头性能良好,能够满足工程中的实际需求.     

Research and Progress in Laser Welding of Wrought Aluminum Alloys. II. Metallurgical Microstructures, Defects, and Mechanical Properties

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.     

Experimental investigation on dissimilar pulsed Nd:YAG laser welding of AISI 420 stainless steel to kovar alloy

This paper presents the results of an investigation on autogeneous laser welding of AISI 420 stainless steel to kovar alloy using a 100 W pulsed Nd:YAG laser. The joints had a circular geometry and butt welded. The joints were examined by optical microscope for cracks, pores and for determining the weld geometry. The microstructure of the weld and the heat affected zones were investigatedby scanning electron microscope. The austenitic microstructure was achieved in the weld. The morphology of weld zone solidification was basically cellural, being influenced by the temperature gradient. It was found that the start of solidification in the kovar side of weld zone occurred by means of epitaxial growth. When the temperature gradient was high, the columnar grains were created in the fusion boundary of 420 stainless steel side toward weld zone. Measurements taken by X-ray spectrometry for dispersion of the energy in the weld zone indicated a significantly heterogeneous distribution of chromium element. The variations in chemical compositions and grains morphologies significantly alter the Vickers microhardness values in the weld zone.     

低温对TC4脉冲激光焊接接头组织和性能的影响

在-120~25℃温度范围内对TC4钛合金薄板脉冲激光焊接接头进行了拉伸试验,并对拉伸断裂后的显微组织进行了观察,研究了低温对TC4钛合金脉冲激光焊接接头组织和力学性能的影响。试验结果表明:随着温度的降低,TC4钛合金脉冲激光焊接接头的显微组织并未出现明显变化,拉伸强度升高而延伸率下降,呈延性断裂模式。在低温拉伸过程中,TC4钛合金脉冲激光焊接接头母材区域的α相中有滑移带形成,预示变形机制仍然是位错滑移机制。     

Chemical and Mechanical Characterization of AISI 304 and AISI 1010 Laser Welding

This paper addresses to the dissimilar laser welding of AISI 304 and AISI 1010 steel thin sheets. Cracks-free dissimilar edge fillet welds have been conducted using a Nd:YAG laser. Geometrical, microstructural, chemical, and mechanical proprieties of the welds were investigated using electron microscopy, EDS and tensile test assisted by digital image correlating. The proper results were achieved at an energy density of 88 J/mm² using a 0.4 mm laser spot diameter. An austenite-ferrite structure characterizes the weld bead and the precipitation of the chromium carbide at the grain limits was observed in the heat affected zone. Good tensile behavior was obtained; dissimilar joint was fractured on the carbon steel side at 482 MPa and 0.35 stain.     

焊接方法对铝合金焊接接头微弧氧化色差的影响

目的 分析铝合金焊接接头微弧氧化过程中色差产生的原因。方法 采用单激光和激光-MIG复合焊2种焊接方法焊接2A12铝合金,利用RGB值定性描述不同焊接试样的色差差异大小,采用金相、SEM和微区XRD观察2A12铝合金单激光和激光-MIG复合焊接头微弧氧化前后的组织、微观形貌和表面物相组成。结果 经微弧氧化处理后,2A12铝合单激光焊焊件的焊缝和母材之间无明显色差,2A12铝合金激光-MIG复合焊焊件的焊缝和母材之间存在明显色差,结合金相组织、表面和截面的SEM形貌以及表面EDS和XRD测试分析结果可知,成分和表面熔融物颗粒的大小不同是铝合金焊接接头微弧氧化色差形成的主要原因,焊接接头的组织对铝合金焊接接头微弧氧化色差的产生没有影响。结论 单激光焊接接头微弧氧化后的氧化色差较激光-MIG复合焊接头的小;铝合金(2A12)焊接接头产生氧化色差主要是因为焊接接头的成分和表面熔融物颗粒大小不同,而组织对色差无影响。     

Q-switch Nd:YAG laser welding of AISI 304 stainless steel foils

Conventional fusion welding of stainless steel foils (<100 μm thickness) used in computer disk, precision machinery and medical device applications suffer from excessive distortion, formation of discontinuities (pore, void and hot crack), uncontrolled melting (melt-drop through) and poor aesthetics. In this work, a 15 ns pulsed, 400 mJ Nd:YAG laser beam was utilized to overcome these barriers in seam welding of 60 μm thin foil of AISI 304 stainless steel. Transmission electron microscopy was used to characterize the microstructures while hardness and tensile-shear tests were used to evaluate the strengths. Surface roughness was measured using a DekTak profilometer while porosity content was estimated using the light microscope. Results were compared against the data obtained from resistance seam welding. Laser welding, compared to resistance seam welding, required nearly three times less heat input and produced welds having 50% narrower seam, 15% less porosity, 25% stronger and improved surface aesthetics. In addition, there was no evidence of δ-ferrite in laser welds, supporting the absence of hot cracking unlike resistance welding.     

汽车高强钢SG1000激光复合焊接力学性能研究

目的 针对汽车高强钢SG1000焊接接头恶化等问题,研究了SG1000激光复合焊接的力学性能。方法 选用等强匹配焊丝MG90-G对高强钢SG1000进行激光复合焊接,对焊接接头进行拉伸和低温冲击韧性试验,并结合扫描和硬度监测等手段对焊缝组织和断口形貌进行分析。结果 由于激光的预热作用,高强钢SG1000激光复合焊接成形件的焊缝美观,焊接过程稳定可靠,焊接熔池深度较大,有效改善了传统焊接的咬边、飞溅、气孔等缺陷。焊缝组织主要由板条马氏体和奥氏体晶粒组成,热影响区的过热区内部板条马氏体和奥氏体晶粒比较粗大,而焊接母材主要为细小的板条马氏体和奥氏体晶粒。焊接拉伸断口主要为细小且较浅的韧窝,且韧窝底部存在第二相粒子及夹杂物,焊接拉伸断口断裂于热影响区且微观形貌为韧性断裂;冲击微观形貌主要由准解理小平面及河流花样组成,且存在一定数量大小不一的韧窝交错分布,焊接冲击断口断裂于热影响区且微观形貌也为韧性断裂。结论 焊缝热影响区的晶粒比非热影响区的晶粒粗大,拉伸和冲击断裂均发生于热影响区;随着激光功率的增大,复合焊接接头的力学性能呈现逐渐增强的趋势;随着焊接速度的增大,复合焊接接头的力学性能呈现先增强后削弱的趋势。高强钢SG1000激光复合焊接最佳工艺参数如下:激光功率为9.5 kW,焊接速度为0.8 m/min,对应屈服强度为1 072 MPa,抗拉强度为1 175 MPa,断裂伸长率为13.5%,冲击断裂吸收的能量为30.8 J、焊缝中心显微硬度为342 HV。     

High-brightness laser welding of thin-sheet 316 stainless steel

Photolytic iodine laser (PIL), a new industrial laser in the market, offers much higher brightness than existing Nd:YAG and CO₂ lasers. PIL has also a unique wavelength (1315 nm) that has not yet been tested for welding applications. In this work, the capabilities of PIL for precision seam welding of 0.1-mm thick sheet of AISI 316 stainless steel in the lap-joint configuration were evaluated. The weld performance data of PIL laser were compared with Nd:YAG and CO₂ lasers. The astounding benefits of PIL weld are narrow seam, extremely fine solidification cell structure, fully austenitic microstructure, and small heat-affected-zone (HAZ). These benefits are attributed to the PIL's high brightness that in turn enables achieving small spot size and energy transport through plasma rather than by heat conduction. In contrast, the welds produced by Nd:YAG and CO₂ lasers exhibited wider seams, coarser solidification structures, duplex microstructures of austenite and ferrite, and larger HAZ due to slow cooling of the melt, and lateral heat diffusion. Despite the narrow seam, the PIL weld carried a high tensile load (92% that of base metal) and was harder than the base metal. Microstructural analysis revealed that PIL welds exhibited fully austenitic structures and were free from hot cracking. These advantages are consequences of the rapid solidification effects including large undercooling, minimal segregation of impurities to the grain boundaries, and fine grain size.     

功率对纯钛薄片激光封孔成形及接头性能的影响

为实现直径为0.1 mm微孔的良好封接,采用低功率脉冲激光对0.40 mm厚的工业纯钛(CP-Ti Grade 1)进行了封焊,采用扫描电镜、显微硬度计及光学显微镜,研究了激光功率对焊缝表面成形、焊接接头横截面形貌和显微硬度的影响规律,分析了接头的微观组织结构.结果表明:当激光功率不低于19.2 W时,微孔可以实现完全封接,且熔核直径随着激光功率的增大而增大,但随着激光功率增大,焊缝凹陷和烧蚀现象越加严重;当激光功率增大时,焊缝表面显微硬度呈上升趋势,激光功率为19.2 W时,焊缝成形良好,且最大显微硬度值可以达到290 HV;焊缝中心微观组织为针状α、锯齿状α以及板条状α晶,焊缝上边缘为锯齿状α晶,而焊缝下边缘为细小的锯齿状α和针状α晶.     

304不锈钢管TIG焊接头凝固行为及热力耦合研究

目的 对2mm厚不锈钢管的焊接工艺参数进行优化,并基于模拟仿真软件对接头的热应力场进行模拟,以解决薄壁管件接头应力测试不方便的问题。方法 以TIG焊对2 mm不锈钢管进行焊接,通过对接头宏观形貌、微观组织、显微硬度等结果进行优化进而得到最佳焊接工艺参数,采用双椭球热源和温度-位移耦合方法结合最优工艺参数进行数值模拟。结果 当焊接电流为150 A、焊接速度为66 cm/min时,焊接接头全部熔透,且正面及背面焊道均匀致密,成形良好。焊缝中心上部区域和下部区域均呈现等轴晶形貌,下部区域尺寸较上部区域尺寸略大,熔合线附近为柱状晶组织。焊接接头显微硬度整体分布呈现U形,其中热影响区显微硬度（197HV）大于焊缝区域硬度（162HV）,熔合线附近显微硬度达到最低值（145HV）。模拟结果显示,在焊接过程中,当纵向残余应力从母材向焊缝中心过渡时,由压应力逐步转化为拉应力;焊缝中心横向应力呈现为压应力,向两侧母材过渡时应力值逐渐趋近于0,径向应力值变化幅度较小,模拟数据变化趋势与实测数据变化趋势接近。     

不锈钢与钛合金纳秒激光焊接工艺研究

目的 针对不锈钢与钛合金异种金属焊接时,容易产生间化合物,导致焊点拉力低的现象,通过纳秒激光焊接工艺来提高不锈钢与钛合金异种金属焊接的焊点拉力.方法 采用纳秒光纤激光器进行304不锈钢与TC4钛合金的焊接实验,通过激光运行螺旋线组成焊点,并对工艺参数进行正交试验,得到焊点拉力最大的工艺参数.结果 当激光功率为90 W,...