Hybrid laser/arc welding of advanced high strength steel to aluminum alloy by using structural transition insert

The present investigation is related to the development of the welding procedure of the hybrid laser/arc welding (HLAW) in joining thick dissimilar materials. The HLAW was applied to join aluminum alloy (AA6061) to an advanced high strength steel (AHSS) where an explosively welded transition joint, TRICLAD®, was used as an intermediate structural insert between the thick plates of the aluminum alloy and AHSS. The welds were characterized by an optical microscope, scanning electron microscope (SEM), tensile test, charged coupled device (CCD) camera, and microhardness measurement. The groove angle was optimized for the welding process based on the allowed amount of heat input along the TRICLAD® interface generated by an explosive welding. The weld was fractured in the heat affected zone of the aluminum side in the tensile test. The microhardness was shown that the temperature variation caused minor softening in the heat affected zone satisfying the requirement that the width of the softened heat affected zone in the steel side falls within 15.9 mm far away from the weld centerline. The microstructure analysis showed the presence of tempered martensite at the vicinity of the weld area, which it was a cause of softening in the heat affected zone.     

Hybrid laser/arc welding of advanced high strength steel in different butt joint configurations

An experimental procedure was developed to join thick advanced high strength steel plates by using the hybrid laser/arc welding (HLAW) process, for different butt joint configurations. The geometry of the weld groove was optimized according to the requirements of ballistic test, where the length of the softened heat affected zone should be less than 15.9 mm from the weld centerline. The cross-section of the welds was examined by microhardness test. The microstructure of welds was investigated by scanning electron microscopy and an optical microscope for further analysis of the microstructure of fusion zone and heat affected zone. It was demonstrated that by changing the geometry of groove, and increasing the stand-off distance between the laser beam and the tip of wire in gas metal arc welding (GMAW) it is possible to reduce the width of the heat affected zone and softened area while the microhardness stays within the acceptable range. It was shown that double Y-groove shape can provide the optimum condition for the stability of arc and laser. The dimensional changes of the groove geometry provided substantial impact on the amount of heat input, causing the fluctuations in the hardness of the weld as a result of phase transformation and grain size. The on-line monitoring of HLAW of the advanced high strength steel indicated the arc and laser were stable during the welding process. It was shown that less plasma plume was formed in the case where the laser was leading the arc in the HLAW, causing higher stability of the molten pool in comparison to the case where the arc was leading.     

10CrNi3MoV钢激光-MAG复合热源焊接技术研究

研究了船用10CrNi3MoV钢激光-MAG复合焊接头组织和力学性能,并与常规MAG焊接头进行了对比。结果表明,采用激光-MAG复合焊接工艺进行10CrNi3MoV钢焊接是可行的;与常规MAG焊相比,激光-MAG复合焊接头显微硬度明显升高,焊缝中心冲击韧性有一定下降,但仍能满足技术指标要求。为进一步改善焊接接头的综合性能,提出通过焊接材料成分优化,来降低焊缝金属淬硬倾向,提高接头的韧性水平。     

铝合金T型接头激光+GMAW复合焊残余应力数值分析

目的 研究激光+GMAW复合焊中不同激光功率参数对铝合金T型接头残余应力的影响,从而提高焊接性能。方法 分别考虑了热弹塑性理论、传热学以及T型接头几何特性,建立了铝合金T型接头激光+电弧复合焊残余应力的数值分析模型。采用双椭球体热源模型表征电弧热输入与熔滴晗,采用锥体热源模型对激光深熔焊进行描述。基于所建立的T型接头模型,使用ANSYS有限元软件对12 mm厚铝合金激光+ GMAW焊T型接头残余应力进行模拟计算,并研究其分布特征;使用X射线衍射法对T型接头处的残余应力进行测量从而对所建模型的准确性进行验证。同时,对比了不同激光功率下铝合金T型接头对残余应力的影响规律。结果 当激光功率分别为2、3、4、5 kW时,铝合金T型接头路径L3上的纵向残余应力最大值分别为270、263、258、251 MPa,米塞斯-等效应力最大值分别为265、261、257、250 MPa。结论 后焊的焊缝A对焊缝B有明显的热处理作用,使应力明显降低;在T型接头焊缝及近缝区,横向残余应力和厚度方向残余应力峰值均比纵向残余应力峰值小,且随着激光功率的增大,焊缝及近缝区拉应力峰值不断减小。     

近红外光纤激光与蓝光半导体激光焊接紫铜工艺对比研究

目的 提高紫铜激光焊接接头的力学性能,并分析激光工艺参数对焊缝外观及焊缝微观组织的影响规律。方法 分别对蓝光半导体激光与近红外光纤激光焊接紫铜的工艺参数进行优化设计,采用光学显微镜观察焊缝的外观形貌,采用拉力机测试焊缝的抗拉强度,采用金相显微镜观察和分析焊缝的微观组织。结果 当采用近红外光纤激光进行焊接时,功率为2 000 W,焊接速度为20 mm/s,焊缝抗拉强度为156 MPa。当采用蓝光半导体激光进行焊接时,功率为500 W,焊接速度为20 mm/s,焊缝抗拉强度为246 MPa,达到母材抗拉强度的80%。结论 由于铜对蓝光波长的吸收率较高,当采用蓝光半导体激光进行焊接时,热量输入较低,焊缝的变形相对较小,并且焊缝中心各个方向上的温度梯度相同,容易形成等轴晶,有利于力学性能的提高。     

ZK60镁合金光纤激光焊接工艺参数及接头性能研究

目的 采用光纤激光对ZK镁合金进行焊接,分析焊接工艺参数对焊接接头性能的影响规律。方法 采用正交实验方法,在焊接过程中对焊接主要的工艺参数比如:激光的功率,焊接的速度,离焦量进行三因素三水平正交实验,采用拉力实验机对焊接接头进行抗拉强度测试,得到抗拉强度最大的工艺参数组合。对焊缝微观组织及断口形貌进行分析。结果 当激光功率为1 400 W、焊接速度为40 mm/s、离焦量为3 mm时,焊缝抗拉强度达到最高的308 MPa,达到母材抗拉强度的95%。结论 在合适的工艺条件下,光纤激光焊接过程中,如果热输入较低,焊接速度过快,导致熔池冷却速度非常快,同时细化了晶粒,提高焊缝接头的综合力学性能。     

Hybrid fiber laser – Arc welding of thick section high strength low alloy steel

Hybrid laser – metal active gas (MAG) arc welding is an emerging joining technology that is very promising for shipbuilding applications. This technique combines the synergistic qualities of the laser and MAG arc welding techniques, which permits a high energy density process with fit-up gap tolerance. As the heat input of hybrid laser – arc welding (HLAW) is greater than in laser welding, but much smaller than in MAG arc welding, a relatively narrow weld and restricted heat affected zone (HAZ) is obtained, which can minimize the residual stress and distortion. Furthermore, adding MAG arc can increase the penetration depth for a given laser power, which can translate to faster welding speeds or fewer number of passes necessary for one-sided welding of thick plates. In this work, a new hybrid fiber laser – arc welding system was successfully applied to fully penetrate 9.3 mm thick butt joints using a single-pass process through optimization of the groove shape, size and processing parameters.     

A comparative study of laser-arc double-sided welding and double-sided arc welding of 6 mm 5A06 aluminium alloy

In order to study the interactions between the two heat sources in both laser-arc double-sided welding (LADSW) and double-sided arc welding (DSAW), some welding characteristics including weld configuration, energy efficiency, weld microstructure and mechanical properties of the both processes were contrastively investigated. The results show that the weld cross-section of LADSW within the proper welding parameter takes on the combination of typical weld profiles of gas tungsten arc welding and laser welding, while the DSAW takes on a quasi-symmetrical shape. The energy efficiency of LADSW is higher than DSAW, probably due to the higher heat transfer efficiency in laser welding and stronger effect of laser on the arc. The weld microstructures of the both processes characterized by scanning electron microscope mainly consist of α and β phase, whereas the grain size and second-phase particle size vary a great deal for the different heat input. The tensile strength of LADSW is 91.7% of base metal, compared with that of 82.3% of DSAW, and the elongation is also higher than DSAW. The fracture micromorphology of LADSW indicates a more typical dimple fracture than that of DSAW. It is considered that the better mechanical properties of LADSW are attributed to the finer grain size.     

Study on arc and laser powers in the hybrid welding of AA5754 Al-alloy

In this paper a new generation of fiber laser assisted by a MIG source was used to weld AA5754-H111 aluminum alloy in 3 mm thick butt configuration. The effects of laser and arc powers on the weld geometry and properties were studied. Weld geometry and porosity were measured. The microstructure was investigated by optical microscope and Vickers micro-hardness was taken. The residual stress close to the heat affected zone was measured by the incremental hole-drilling method. Eventually, the tensile test was conducted in order to compare the mechanical properties of the weld with those of the parent metal.For the first time the sensitiveness of the hybrid welding of the 5754 aluminum alloy to the arc and laser powers was demonstrated. Higher laser power favored the stability of the process and provided good structural and geometrical properties of the weld. Further investigation can be performed in order to optimize the weld soundness and the energy efficiency of hybrid welding an aluminum alloy using a fiber laser.     

热输入对Inconel 617镍基高温合金激光焊接接头显微组织与力学性能的影响EI北大核心

采用两种热输入不同的焊接工艺参数对3 mm壁厚的Inconel 617镍基高温合金进行激光焊接。通过光学显微镜和扫描电子显微镜对焊接接头显微组织进行观察分析,并测试了焊接接头在室温(25℃)及高温(900℃)下的拉伸性能。结果表明:激光焊接热输入对Inconel 617焊接接头显微组织及力学性能影响明显。在高热输入(200 J/mm)条件下,焊缝正面宽度3.88 mm,熔化区中部晶粒尺寸粗大,取向杂乱,树枝晶二次枝晶间距较大(6.71μm),枝晶间碳化物颗粒尺寸较为粗大,枝晶间Mo,Cr等合金元素的凝固偏析较为严重。焊接接头热影响区宽度约0.29 mm,在晶界和晶内形成了γ+碳化物共晶组织,这是由于焊接升温过程中,热影响区内球状碳化物颗粒与周边奥氏体发生组分液化,并在焊后凝固过程中形成共晶。低热输入(90 J/mm)工艺参数获得的焊缝正面宽度为2.28 mm,焊缝呈沿熔合线母材外延生长并沿热流方向定向凝固形成的柱状晶形态。焊缝中部树枝晶二次枝晶间距较小(2.26μm),枝晶间碳化物颗粒尺寸细小,热影响区宽度约0.15 mm。室温(25℃)拉伸测试表明:高热输入下获得的焊接接头由于焊缝中固溶元素偏析造成的局部组织弱化,从焊缝中部破坏,强度与伸长率有所降低,低热输入条件下获得的焊接接头从母材破坏。而高温实验条件下(900℃),母材晶界发生弱化导致所有试样均从母材破坏。     

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...     

6009铝合金光纤激光-MIG电弧复合焊和光纤激光焊工艺对比研究

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。     

Effect of heat input on the microstructure and mechanical properties of gas tungsten arc welded AISI 304 stainless steel joints

Influence of heat input on the microstructure and mechanical properties of gas tungsten arc welded 304 stainless steel (SS) joints was studied. Three heat input combinations designated as low heat (2.563 kJ/mm), medium heat (2.784 kJ/mm) and high heat (3.017 kJ/mm) were selected from the operating window of the gas tungsten arc welding process (GTAW) and weld joints made using these combinations were subjected to microstructural evaluations and tensile testing so as to analyze the effect of thermal arc energy on the microstructure and mechanical properties of these joints. The results of this investigation indicate that the joints made using low heat input exhibited higher ultimate tensile strength (UTS) than those welded with medium and high heat input. Significant grain coarsening was observed in the heat affected zone (HAZ) of all the joints and it was found that the extent of grain coarsening in the heat affected zone increased with increase in the heat input. For the joints investigated in this study it was also found that average dendrite length and inter-dendritic spacing in the weld zone increases with increase in the heat input which is the main reason for the observable changes in the tensile properties of the weld joints welded with different arc energy inputs.     

A transient finite element simulation of the temperature and bead profiles of T-joint laser welds

Laser welding is a high power density welding technology, which has the capability of focusing the beam power to a very small spot diameter. Its characteristics such as high precision and low and concentrated heat input, helps in minimizing the micro-structural modifications, residual stresses and distortions on the welded specimens. In this study, finite element method (FEM) is adopted for predicting the bead geometry in laser welding of 1.6 mm thick AISI304 stainless steel sheets. A three-dimensional finite element model is used to analyze the temperature distribution in a T-joint weld produced by the laser welding process. Temperature-dependent thermal properties of AISI304 stainless steel, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. The heat input to the model is assumed to be a 3D conical Gaussian heat source. The finite element code SYSWELD, along with a few FORTRAN subroutines, is employed to obtain the numerical results. The T-joint welds are made using a Nd:YAG laser having a maximum power of 2 kW in the continuous wave mode. The effect of laser beam power, welding speed and beam incident angle on the weld bead geometry (i.e. depth of penetration and bead width) are investigated. Finally, the shapes of the molten pool predicted by the numerical analysis are compared with the results obtained through the experimentation. The comparison shows that they are in good agreement.     

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。     

电弧电流对AZ31B/DP980激光诱导电弧焊接接头成形及力学性能的影响

采用激光诱导钨极惰性气体保护(tungsten inert gas, TIG)电弧焊接技术,在未添加任何夹层和镀层的条件下,通过优化工艺,获得了AZ31B镁合金和DP980高强钢高质量搭接焊接头,重点研究TIG电弧电流对焊接接头成形和力学性能的影响规律。结果表明：电弧电流的增大会提高镁合金在高强钢的润湿铺展能力,提升焊缝宽度的同时减小润湿角。镁合金/钢焊接接头的最大拉伸载荷随着电弧电流的增大先升高后降低,接头断裂模式由沿界面断裂转变为沿焊缝断裂。当TIG电流为80 A、激光功率为350 W时,焊接接头最大平均拉伸载荷达到279 N/mm。焊缝宽度和界面层厚度的增大以及激光匙孔的钉扎作用共同提升了镁合金/钢的接头性能。     

预变形对304L焊接组织的影响

基于某汽车公司提出的曲面焊接设计需求,研究了变形对焊接组织的影响。选用熔化极气体保护焊在奥氏体不锈钢304L的T型接头和变形钢板上焊接,寻求合理的变形后焊接参数并观察变形对焊接组织的影响。得到合理焊接参数为焊枪速率4mm/s,送丝速率2.5m/min,电压1 7V。在T型和变形后焊接中,焊趾分别处于应变为0%,30%的区域,观察到变形后焊接件中熔化区和部分熔化区范围减小,焊接接头碳化物沉积和晶间铁素体数量减小。304L变形后焊接获得了更为均匀的接头组织。     

Effect of heat input and weld chemistry on mechanical and microstructural aspects of double side welded austenitic stainless steel 321 grade using tungsten inert gas arc welding process

Stainless steel 321 is a stabilized austenitic grade that prevents the formation of chromium carbides at the grain boundaries and subsequently reduces the risk of corrosion attack at the weld surface by forming titanium carbide. It is primarily used in industries such as pressure vessels, boilers, nuclear reactors, carburetors and car exhaust systems. In order to assess the effect of gas tungsten arc welding process parameters on weld penetration, the proposed Taguchi L₉ orthogonal matrix has been selected with two factors and three levels for welding austenitic stainless steel 321 by adjusting the welding current and welding speed. Bead-on-plate experiments were performed on base metal of 6 mm thick plate by changing the process parameters, and corresponding weld bead measurement and macrostructure images are examined. Maximum depth of penetration −3.3017 mm is achieved with a heat input −1.4058 kJ/mm, i. e., welding current-220 A and welding speed-120 mm/min. Double-side arc welding technique is used to obtain full penetration on 6 mm thick plate. The quality of the weldment was assessed using non-destructive radiography inspection. Mechanical integrity and microstructural characteristics of the weldments were studied using tensile (transverse and longitudinal), bend, impact, microhardness, optical microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction analysis, ferrite number measurement and scanning electron microscope. The results reveal that the double side-tungsten inert gas weldment have better mechanical properties. It is corroborated from the weld metal microstructure that it contains γ-austenite, δ-ferrite and titanium carbides (intermetallic compounds). X-ray diffraction analysis and energy dispersive x-ray spectroscopy plots confirm the increase in the ferrite phase in weld metal. The ferrite measurement results show that the ferrite volume in the base metal and weld metal is 1.2 percent and 6.1 percent respectively. In addition, the higher δ-ferrite volume in the weldment helps in attaining superior mechanical integrity. Fractography shows that the failure mode of the weld metal and the base metal is ductile.     

Mechanical performance optimization of similar thin AA 7075-T6 sheets produced by refill friction stir spot welding

Refill friction stir spot welding was applied to weld similar thin AA 7075-T6 aluminum alloy sheets in a spot-like joint configuration without a keyhole. The welds were produced using a small tool consisting of sleeve and probe with diameters of 6 mm and 4 mm, respectively. Design of experiment was employed to optimize the welding parameters in terms of the cross tensile strength by using Box Behnken Design. Based on analysis of variance, it can be concluded that plunge depth strongly affects the mechanical performance of the weld. Optimal welding parameters in terms of rotational speed, plunge depth and speed are identified to reach a cross tensile strength of up to 660 N.     

Metallurgical characterization of pulsed current gas tungsten arc,friction stir and laser beam welded AZ31B magnesium alloy joints

This paper reports the influences of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on mechanical and metallurgical properties of AZ31B magnesium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy and X-Ray diffraction technique were used to evaluate the metallurgical characteristics of welded joints. LBW joints exhibited superior tensile properties compared to FSW and PCGTAW joints due to the formation of finer grains in weld region, higher fusion zone hardness, the absence of heat affected zone, presence of uniformly distributed finer precipitates in weld region.