工业纯钛光纤激光-MIG复合焊接工艺及性能

采用光纤激光与熔化极惰性气体保护电弧焊(MIG焊)复合焊接工业纯钛,分别对激光焊、MIG焊和复合焊接头的焊缝表面成形、横断面进行了观察,并进行了激光焊和复合焊接头的拉伸试验及杯突试验.结果表明,复合焊的电弧稳定性比MIG焊显著提高,焊接速度可提高7倍;复合焊与激光焊接头的抗拉强度高于母材;复合焊接头的杯突值优于激光焊接头的杯突值,这是因为复合焊焊缝的微观组织有利于接头的塑性.因此,采用光纤激光-MIG电弧复合焊接方法很好地实现了工业纯钛的高速焊接,焊缝成形良好,接头的塑性优于单一激光焊的塑性.

Abstract：

Fiber laser-metal inert gas (MIG) arc hybrid welding was used to weld the commercial pure titanium (CP-Ti). The weld appearance, cross section, tensile strength, Erichsen value and microstructure of the CP-Ti welded joints were studied. The results show that the arc stability is substantially improved and the welding speed can be increased to 7 times by fiber laser-MIG hybrid welding. The welded joints by laser welding and the hybrid welding exhibit the higher ultimate tensile strength than those of the base metal. In addition, the welded joint by the fiber laser-MIG hybrid welding has higher Erichsen values than that by laser joints. The difference in plasticity is attributed to the microstructure changes in the welded joint of hybrid welding. Thus, the fiber laser-MIG hybrid welding of CP-Ti can be carried out suecessfully at higher welding speed with a good combination of weld bead appearance and plasticity.     

活性剂对激光-电弧复合焊接的影响

提出了激光-电弧复合活性焊接法,以提高小功率激光-电弧复合焊接的熔深.在待焊不锈钢表面涂覆一层活性剂,然后进行激光-电弧复合焊接.研究了工艺参数对焊缝成形性的影响,并对焊接接头的组织性能进行了分析.结果表明,涂覆活性剂后可以使复合焊接的熔深增加,并且可以细化复合焊焊缝组织.复合焊接头与复合活性焊接头的显微硬度变化规律一致.复合活性焊接头的抗拉强度较高,达到母材抗拉强度的92%.复合活性焊接头的腐蚀速率低于复合焊接头的腐蚀速率,具有良好的耐蚀性能.     

Hybrid laser-arc welding of aluminium alloys

Special features of laser welding of aluminium alloys with laser and arc heat sources are investigated. Advantages and shortcomings of these methods are noted. Experiments were carried out to combine laser and arc heat sources for welding aluminium alloys. Equipment for hybrid welding is described. The technological parameters influencing the external formation of the welded joints are determined. Specific conditions for welding 1424 aluminium alloys with a thickness of 4.0 mm are presented. High-quality welded joints were produced by hybrid laser-arc welding in 1424 alloy with a thickness of 4.0 mm.     

A novel ultrafast-convert hybrid pulse square-wave VP-GTAW process for aluminum alloys

A novel ultrafast-convert hybrid pulse square-wave variable polarity arc welding power source was developed.The variable polarity current which crossed zero with no dead time possessed the ultrafast converting speed and the series of ultrasonic pulse current were superimposed in the positive polarity current duration.A high-efficiency hybrid pulse variable polarity gas tungsten arc welding (HPVP-GTAW) process for aluminum alloys was achieved.With X-ray inspeetion,microstructure analysis,tensile tests and scanning electron microscopy (SEM) for fracture surface,the square butt welding characteristics of 5A06,2AI4 and 2219 aluminum alloys were tested,respectively.Experimental results show that microstructure and mechanical properties of these aluminum alloy welded joints are influenced significantly by the introduction of ultrasonic pulse current.The weld quality is improved predominantly by the novel HPVP-GTA W process.     

铝合金双光束/单光束激光-TIG复合焊

针对4mm厚5A06铝合金,分析了双光束光纤激光-TIG复合焊的焊缝成形特点、气孔率、匙孔动态特征及接头力学性能,并与单光束光纤激光-TIG复合焊对比。结果表明,在获得相同焊缝背面熔宽条件下,与单光束激光-TIG复合焊相比,双光束激光-TIG复合焊的焊缝背面成型连续性、均匀性更优且熔宽波动较小,焊缝气孔率降低50%以上,激光匙孔开口面积平均值更大,波动变异系数更小;双光束激光-TIG复合焊接头抗拉强度、断后伸长率、显微硬度、组织与单光束激光-TIG复合焊结果差别不大。     

铝合金激光-MIG双面焊接接头组织和性能研究

针对16mm厚1561铝合金(俄罗斯牌号),采用不开坡口无间隙的双面激光-MIG复合焊接工艺,并研究焊接接头的拉伸性能、显微硬度和微观组织。结果表明,采用较大的激光功率使双面焊道交叉面积增大,有利于减少焊道根部缺陷,提高拉伸性能;接头中存在着基体相α-Al和第二相Fe(Mn Al)6,第二相经焊接热循环重熔后弥散分布,其中单独激光作用区弥散度最高;焊缝硬度在激光单独作用区相对于母材升高,而在激光-电弧复合作用区相对于母材降低,这与焊缝显微组织中的第二相数量和形态密切相关。     

焊后热处理对6063铝合金激光填丝焊接头组织与性能的影响

采用激光填丝焊对6063铝合金进行焊接,并对焊接接头进行人工时效和固溶+人工时效的热处理。通过光学显微镜、扫描电镜观察及拉伸试验,对焊后经不同热处理的焊接接头组织和性能进行研究。结果表明:未热处理的焊接接头抗拉强度为196 MPa,焊缝内部为铸态组织,弥散分布着Mg₂Si强化相,熔合线附近存在向焊缝内部生长的粗大柱状晶,焊缝内部为细小的树枝晶,焊缝中心为等轴晶;经时效处理后,焊接接头组织不均匀性和强化相的分布得到改善,焊接接头抗拉强度提高27 MPa;经固溶+时效处理的焊接接头抗拉强度提高64 MPa,焊缝组织、熔合区及热影响区组织得到显著细化。焊接接头均为韧脆混合断裂;时效处理的断口韧窝大小差异较大,韧窝较深;固溶+时效处理后的断口韧窝大小均匀,韧窝尺寸较大较深,韧窝数量更多。     

HPVP-GTAW电弧力及焊接质量分析

分别以3种不同材质铝合金平板材料为试验对象,研究分析了复合超高频脉冲方波变极性钨极氩弧焊接(HPVP-GTAW)过程中电弧力的变化及其对焊缝成形特征和接头力学性能的影响.结果表明,与常规变极性氩弧焊工艺相比,脉冲方波电流的加入使得HPVP-GTAW电弧力显著增加,同时焊缝熔透率大幅提高,接头力学性能得到明显改善和提高;保持脉冲电流幅值和占空比基本不变,在10～80 kHz范围内,脉冲电流频率对焊接过程产生了重要影响,频率为40 kHz时,HPVP-GTAW电弧力和焊缝熔透率均达到最大,分别约为常规变极性焊接电弧的1.9倍和1.7倍.     

镁铝异种金属激光-TIG复合热源焊焊接性分析

采用激光-TIG复合热源和TIG焊接异种金属镁和铝，利用X射线衍射仪、金相显微镜和扫描电镜研究镁和铝焊接接头的微观组织、元素分布。结果表明，TIG焊接镁和铝形成连续的金属间化合物层，导致镁和铝接触的界面开裂，不能实现有效的连接。激光-TIG复合热源由于其焊接速度高和对熔池的快速搅拌作用，使镁和铝形成的金属间化合物由连续的层状变成弥散的状态，改善了异种金属镁和铝的焊接性。镁和铝激光-TIG复合热源焊接的焊缝成形均匀，美观。     

Fatigue Performance of Gas Tungsten Arc, Electron Beam, and Laser Beam Welded Ti-6Al-4V Alloy Joints

Titanium alloys have been successfully applied for aerospace, ship, and chemical industries because they possess many good characteristics such as high strength to weight ratio, superior corrosion resistance, and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. The evaluation and prediction of fatigue life are very important for the welded joints to avoid catastrophic failure particularly in titanium alloys. This article compares the fatigue performance of Ti-6Al-4V alloy fabricated by gas tungsten arc welding, laser beam welding, and electron beam welding processes. The resultant fatigue properties of the welded joints are correlated with the tensile properties and microstructural characteristics. Of the three processes considered the joint welded by laser beam welding exhibits higher fatigue limit when compared with the other two processes due to the presence of fine lamellar microstructure in the weld metal region.     

Investigation into properties of laser welded similar and dissimilar steel joints

Abstract

Laser beam welding is currently used in the welding of steels, aluminium alloys, thin sheets, and dissimilar materials. This high power density welding process has unique advantages of cost effectiveness, deep penetration, narrow bead and heat affected zone (HAZ) widths, and low distortion compared to other conventional welding processes. However, the metallurgical and mechanical properties of laser welds and the response of conventional materials to this new process are not yet fully established. The welding process may lead to drastic changes in the microstructure with accompanying effects on the mechanical properties and, hence, on the performance of the joint. The thermal cycles associated with laser beam welding are generally much faster than those involved in the conventional arc welding processes. This leads to the formation of a rather small weld zone that exhibits locally a high hardness in the case of C–Mn structural steels owing to the formation of martensite. It is currently difficult to determine the tensile properties (full stress–strain curves) of the laser welded joint area owing to the small size(～V 2·3 mm) of the fusion zone. Complete information on the tensile and fracture toughness properties of the fusion zone is essential for prequalification and complete understanding of the joint performance in service, as well as for conducting a defect assessment procedure on such welded joints. Therefore, an experimental investigation into the mechanical properties of laser welded joints was carried out to establish a testing procedure using fiat micro tensile specimens (0·5 mm in thickness, 2 mm in width) for determination of the tensile properties of the weld metal and H AZ of the laser beam welds. Three similar joints, namely St 37–St 37, St 52–St 52, and austenitic–austenitic, and two dissimilar ferritic–austenitic joints were produced by CO₂ laser, using 6 mm thickness plates. The mechanical properties have been examined by microhardness survey and testing of conventional transverse tensile, round tensile, and fiat microtensile specimens. The results for the micro tensile specimens were compared with those for standard round tensile specimens and this clearly showed the suitability of the microtensile specimen technique for such joints.     

激光功率对激光-双丝脉冲MIG复合焊接电弧形态及熔滴过渡的影响

通过搭建激光-双丝脉冲MIG复合焊接系统,利用高速摄像与电信号采集系统对激光-双丝脉冲MIG复合焊接在不同激光功率下的电压电流信号及高速摄像信号进行同步采集,研究激光功率对焊接过程的电弧形态、熔滴过渡过程的影响.结果发现,由于激光等离子体与电弧等离子体的相互作用,电弧形态和熔滴受力状态发生改变.随着激光功率的增大,激光对电弧的吸引能力增强,促进熔滴过渡的等离子流力竖直向下的分力减小,熔滴过渡频率降低.     

10Ni3CrMoV钢CO2激光多层焊的接头组织与性能

与传统电弧焊相比,激光焊接厚板优势明显。采用纯激光焊和激光电弧复合焊等多道焊接技术实现了28 mm厚10Ni3CrMoV钢的高效焊接,采用光学显微镜分析焊缝、热影响区和焊缝重叠区的组织,激光复合焊缝组织主要为针状铁素体,纯激光焊缝、粗晶区和细晶区组织主要为板条马氏体,激光复合焊缝重叠区组织为粒状贝氏体+马氏体,纯激光焊缝和激光复合焊缝重叠区组织为马氏体+少量粒状贝氏体。测试了焊接接头的力学性能,结果表明,激光复合焊缝金属的冲击韧性较高,焊接接头的抗拉强度和屈服强度与母材相当,延伸率略小于母材,焊接接头的最大硬度小于360 HV,弯曲性能合格。     

低功率YAG激光-MAG电弧复合焊接不锈钢

以0Cr18Ni9Ti不锈钢钢板为试验材料,研究了低功率脉冲YAG激光-脉冲MAG电弧复合热源和单脉冲MAG焊接不锈钢.结果表明,低功率脉冲YAG激光-脉冲MAG电弧复合热源同样具有大功率激光-电弧复合焊接才有的增加熔深、提高焊接速度、稳定焊接过程等优点;低功率脉冲YAG激光的加入改变了电弧形态,电弧根部被吸引和压缩现象显著,提高了能量利用率;与单脉冲MAG堆焊相比,在相同焊接速度下复合焊最大能增加熔深1.3倍,在相同熔深下复合焊的焊接速度可以提高50%;复合焊焊缝的晶粒较单MAG焊缝中的晶粒细小,其焊缝抗拉强度比单MAG的好,断裂属于延性断裂.     

Al-Mg-Si6082合金氩弧焊焊接接头的气孔与合金元素烧损

对3和10mm厚的Al-Mg-Si6082合金分别进行了TIG焊和MIG焊,获得了成形良好、表面无缺陷的焊接接头.通过对焊缝进行金相试验,研究了TIG焊和MIG焊时焊缝中气孔的种类与差异,并分析了产生气孔差异的原因;通过对Mg,Si合金元素成分含量的测定,揭示出了Mg,Si合金元素氩弧焊时的烧损规律.结果表明,MIG焊时,焊缝中易出现皮下气孔、肩下气孔和心气孔;Mg,Si元素在焊缝中部的烧损最为严重,越靠近热影响区元素的烧损程度越轻;Mg元素的烧损率明显高于Si元素;MIG焊时,Mg,Si元素的烧损率与弧长成反比.     

Mechanical properties and microstructures of hybrid laser MIG welded dissimilar Mg–Al–Zn alloys

Abstract

Bead shape, microstructure changes and mechanical properties of laser metal inert gas (MIG) welded dissimilar Mg–Al–Zn alloys (from AZ31B to AZ61) are studied. The results show that heat ratio of arc to laser (HRAL) and welding speed are dominant parameters for achieving good tensile strength efficiency and elongation property. From AZ31B to AZ61, microstructure changes are observed as cellular dendrites to equiaxed dendrites and fish bone dendrites in the upper part of hybrid weld. Besides, at weld centreline, the solidification structure of lower part is finer than that of upper part. In this study, the maximum tensile strength efficiency and elongation reached 97·6 and 7% respectively. When the HRAL matches welding speed well, the joint achieves higher tensile strength with 45° shearing fracture at heat affected zone because of fewer defects. However, when utilising too low HRAL or fast welding speed, the joints show lower tensile strengths with nearly vertical fracture at fusion zone.     

能源节约型激光诱导电弧复合焊技术及应用

围绕低能耗绿色焊接制造技术及理论开展研究,阐述低功率激光与电弧之间的相互作用机理,提出低功率脉冲激光诱导电弧复合高效焊的设计思想,建立了能源节约型的复合焊制造技术体系. 结果表明,采用低功率脉冲激光对电弧进行诱导使电弧能量密度显著提高,实现了激光与电弧两种热源之间的良好调控. 采用低功率激光诱导电弧复合焊技术成功实现了镁合金、钛合金及钢铁等多种金属材料的优质高效焊接. 该技术的发展为实现低能耗绿色焊接制造起到了积极的推动作用.     

两种规格超细晶粒钢的激光焊接

超细晶粒钢依靠微米级或亚微米级的铁素体,使钢的强度和韧性大大提高。本文分析了超细晶粒钢的焊接性及激光焊接的特点,进行了超细晶粒钢的激光焊接试验,并与等离子弧焊接、MAG焊接进行了比较,超细晶粒钢激光焊接接头粗晶区有较好的韧性,采用较小的激光功率并配合较慢的焊接速度,可减小粗晶区硬化倾向。终轧温度较高的SS400钢激光焊接接头强度高于母材,深度轧制钢激光焊接接头出现再结晶软化区,当软化区宽度较窄时,不影响整体接头强度,SS400钢和深度轧制钢激光焊接接头均有好的弯曲塑性。     

Microstructure and mechanical properties of the joint of 6061 aluminum alloy by plasma-MIG hybrid welding

Plasma-MIG (metal inert gas arc welding) hybrid welding of 6061 aluminum alloy with 6 mm thickness using ER5356 welding wire was carried out.The microstructures and mechanical properties of the welded joint were investigated by optical microscopy,X-ray diffraction (XRD),energy dispersive spectroscopy (EDS),tensile test,hardness test and scanning electron microscope (SEM) were used to judge the type of tensile fracture.The results showed that the tensile strength of welded joint was 142 MPa which was 53.6％ of the strength of the base metal.The welding seam zone was characterized by dendritic structure.In the fusion zone,the columnar grains existed at one side of the welding seam.The fibrous organization was found in the base metal,and also in the heat affected zone (HAZ) where the recrystallization occurred.The HAZ was the weakest position of the welded joint due to the coarsening of Mg2Si phase.The type of tensile fracture was ductile fracture.     

Using MathCAD software for studying non‐stationary thermal processes in welding

Investigations were carried out into the problems of increasing the productivity of automatic MIG welding of aluminium alloys and improving the quality of droplet transfer of electrode metal and of welded joints by studying the effect of high-speed processes of ultrafine activating fluxes on the properties of the welding arc and the formation of the welded joint.