Weld metal ductility in aluminum tailor welded blanks

The objective of the research described in this article was to characterize and numerically describe the ductility of weld material in aluminum tailor welded blanks under uniaxial tension conditions. Aluminum tailor welded blanks consist of multiple thickness and alloy sheet materials welded together into a single, variable thickness blank. To evaluate the mechanical properties of the weld material in these tailor welded blanks, a series of tensile specimens containing varying ratios of weld and monolithic material in the gage area of the specimen were tested. These experimental results show that increasing the amount of weld in the cross-sectional area of the specimen decreases the ductility of the specimen and that the weld characteristics have a pronounced impact on ductility. Using the experimental results and classical tensile instability and necking models, a numerical model was developed to describe the ductility of the weld metal. The model involves basic material properties and an initial imperfection level in both the weld and monolithic materials. The specimens studied were produced from 1- to 2-mm AA5182-O aluminum alloy sheet material welded into blanks using an autogenous gas tungsten arc welding process.     

6005A铝合金CMT与MIG焊接头组织及性能研究

针对2mm厚6005A铝合金采用冷金属过渡(CMT)和熔化极惰性气体保护(MIG)焊接技术进行焊接,研究了两种焊接接头的力学性能、拉伸断口形貌,接头不同位置的微观组织。研究表明,CMT焊接头的抗拉强度好于MIG焊接头,达到母材的70%,焊缝组织更为细小;两种焊接接头断裂位置均为热影响区,CMT焊接接头为韧性断裂,MIG焊接接头为韧性断裂与准解理断裂的混合断裂。     

Microstructure and mechanical properties of Al-Mg-Mn-Zr-Er weld joints filled with Al-Mg-Mn-Zr and Al-Mg-Mn-Zr-Er weld wires

The Al-Mg-Mn-Zr-Er alloy sheets with a thickness of 4 mm were welded by TIG welding, the microstructures and mechanical properties of Al-Mg-Mn-Zr-Er alloy weld joints filled with F1.6 mm Al-Mg-Mn-Zr and Al-Mg-Mn-Zr-Er welding wires were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy, hardness testing and tensile mechanical properties testing. The result showed that, the tensile strength increased by 57 MPa and the coefficient of weld joint reached 0.8 when Al-Mg-Mn-Zr-Er welding wire was used as filling material. The tensile strength and elongation of weld joint filled with Al-Mg-Mn-Zr-Er welding wire were 19% and 85% higher those that of filled with Al-Mg-Mn-Zr welding wire respectively, which resulted from grain refinement strengthening and dispersion strengthening of Al₃Er.     

国产A6N01铝合金型材MIG焊接头的微观组织与力学性能

利用金相观察、显微硬度测定、拉伸和弯曲性能测试等方法研究了A6N01-T5铝合金型材MIG焊接接头的显微组织和力学性能.结果表明：焊接接头焊缝中心金属为明显的激冷形成的铸态组织,呈等轴晶状;熔合区靠近焊缝侧的结晶形态为沿散热方向排列的柱状晶,邻近熔合区的热影响区晶粒粗化.焊缝中心处具有较高的显微硬度,在距离焊缝中心10~12 mm处的热影响区显微硬度值最低.国产A6N01-T5铝合金型材焊接接头抗拉强度达到欧洲标准DIN EN 288-4的要求.     

Structure and mechanical properties of 1570C alloy welds produced by friction stir welding

The effect of the conditions of friction stir welding (FSW) of 1570C aluminum alloy sheets on the structure and mechanical properties of the welded joints is studied. A recrystallized fine-grained structure with a grain size changing with the rate of welding tool rotation forms in a weld during FSW. As compared to the base metal, the yield strength of the weld metal decreases by 9–22% depending on the rate of welding tool rotation, and the ultimate tensile strength is almost independent of the FSW conditions and accounts for ～90% of the ultimate tensile strength of the base metal. The plasticity of the weld metal is >13% for all rates of welding tool rotation. The microstructure and mechanical properties of the weld zone are discussed.     

Cold Metal Transfer Welding of Dissimilar A6061 Aluminium Alloy-AZ31B Magnesium Alloy: Effect of Heat Input on Microstructure,Residual Stress and Corrosion Behavior

Lap joints of aluminum alloy A6061-T6 and AZ31B magnesium alloy were produced by cold metal transfer welding with Al-5 %Si filler metal. Four heat inputs designated as A (175 J/mm), B (185 J/mm), C (195 J/mm) and D (205 J/mm) were used during the process and the joints made were subjected to analysis of microstructure, mechanical properties and corrosion behaviour. The thickness of the fusion line (diffusion layer) varied from 3 to 12 µm depending on the heat input. It was also found that the joints made using the heat input of 205 J/mm exhibited highest tensile strength of 360 N/mm, least tensile stress in the weld and better pitting corrosion resistance. Electron microscopy study of the weld revealed the presence of β′-Mg₂Si, Al₆Mn and β-Al₃Mg₂ particles. X-ray diffraction study in the weld revealed the formation of γ-Al₁₂Mg₁₇ and β-Al₃Mg₂ phase with Mg₂Si strengthening precipitates. Tensile failure occurred at the fusion line near magnesium.     

Influence of Mode of Metal Transfer on Microstructure and Mechanical Properties of Gas Metal Arc-Welded Modified Ferritic Stainless Steel

This article describes in detail the effect of the modes of metal transfer on the microstructure and mechanical properties of gas metal arc-welded modified ferritic stainless steel (SSP 409M) sheets (as received) of 4 mm thickness. The welded joints were prepared under three modes of metal transfer, i.e., short-circuit (SC), spray (S), transfer, and mix (M) mode transfer using two different austenitic filler wires (308L and 316L) and shielding gas composition of Ar + 5 pct CO₂. The welded joints were evaluated by means of microstructural, hardness, notched tensile strength, Charpy impact toughness, and high cycle fatigue. The dependence of weld metal microstructure on modes of metal transfer and filler wires has been determined by dilution calculation, WRC-1992 diagram, Cr_eq/Ni_eq ratio, stacking fault energy (SFE), optical microscopy (OM), and transmission electron microscopy (TEM). It was observed that the microstructure as well as the tensile, Charpy impact, and high cycle fatigue of weld metal is significantly affected by the mode of metal transfer and filler wire used. However, the heat-affected zone (HAZ) is affected only by the modes of metal transfer. The results have been correlated with the microstructures of weld and HAZ developed under different modes of metal transfer.     

不同5xxx系焊丝对5182-H111组织和性能的影响

使用3种焊丝ER 5183、ER 5356、ER 5554对6mm 5182-H111铝合金板材进行半自动MIG焊对接试验,通过对焊接接头进行力学性能试验、显微硬度测试及金相组织的观察,探究3种焊丝对5182-H111铝合金组织和性能的影响。结果表明,使用3种焊丝所焊接头中,ER 5183及ER 5356接头抗拉强度均大于ISO 15614-22005要求的焊缝接头系数(1.0),而ER 5554接头焊缝系数仅为0.949;3种焊丝所焊接头硬度均在焊缝区及热影响区有所降低,其中ER 5356所焊接头焊缝强度较其他两种焊丝焊缝区硬度高,为85.5HV;3种焊丝所焊接头组织形貌相近,均存在β(Mg2Al3)强化相,但由于ER 5183与ER 5356焊丝中含有更多的Mg,因此生成了更多的β(Mg2Al3)相,使得焊缝组织更加致密。     

Effect of Process Parameters on Microstructure and Mechanical Properties in Friction Stir Welding of Aluminum Alloy

Friction stir welding process is a promising solid state joining process with the potential to join low melting point materials, particularly aluminum alloys. The most attractive reason for this is the avoidance of solidification defects formed during conventional fusion welding processes. Tool rotational speed and the welding speed play a major role in deciding the weld quality. In the present work an effort has been made to study the effect of the tool rotational speed and welding speed on mechanical and metallurgical properties of friction stir welded joints of aluminum alloy AA6082-T651. The micro hardness profiles obtained on welded zone indicate uniform distribution of grains in the stir zone. The maximum tensile strength obtained is 263 MPa which is about 85% of that of base metal. Scanning electron microscope was used to show the fractured surfaces of tensile tested specimens.     

装甲车用7A52铝合金焊接性研究

针对兵器工业用7A52铝合金,从焊接工艺参数、焊后无损检测,以及破坏性实验力学性能、弯曲性能、宏观检测、焊接接头显微硬度等方面进行试验研究。结果表明,7A52铝合金焊接性能良好,接头拉伸、弯曲性能较好,抗拉强度达到274.8MPa,接头硬度曲线分布表明强度最低区域为焊缝。     

Effect of welding processes on tensile, impact, hardness and microstructure of AISI 409M ferritic stainless joints fabricated using duplex stainless steel filler metal

 The present investigation is aimed at to study the effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, micro hardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigation, it is found that gas tungsten arc welded joints of ferritic stainless steel showed superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.     

Performance evaluation of OOCr11NbTi perforated-plasma-arc-welded joint

Based on a 00CrllNbTi ferritic stainless steel plate produced by Baosteel,the plasma arc welding was performed without filler wire.The mechanical properties of the welded joints were tested,as a result,the transverse tensile strength of the welded joints decreased to a certain extent in comparison with that of the base metal,but the bending performance and plasticity of the welded joint were good.     

车体铝合金线槽无焊丝塞焊工艺研究

在原有焊接工艺特点的基础上,针对车体铝合金线槽2mm薄板的焊接特点,通过减小焊接电流、增大焊接间隙、改焊丝填充塞焊为母材填充的方式,对车体线槽焊接工艺进行了优化试验研究。结果表明：采用电流为90A、母材突出为1．5mm,装配间隙为1mm的焊接工艺可以获得较好的效果。该工艺不但减少了产品的焊后变形、避免了产品焊穿现象的发生、增大了焊缝熔深,同时,降低了产品的生产成本,提高了劳动工作效率,对于提高类似产品的质量及生产具有积极的作用。     

Studies on Characteristics of Ti6Al4V/AA2024 Dissimilar Weld Joint Using Laser Beam Focusing from AA2024 Side

Laser beam welding is based on interaction between the laser beam and parent metals. Methods have been developed in recent years to produce joints of most light metals and their combinations. It provides good weld joint to simplify the structure and reduce the weight and cost to meet the main concerns of the aircraft industry. To achieve these, Ti6Al4V and AA2024 alloy sheets with a thickness of 1.0 mm have been welded with butt joint configuration using pulsed Nd:YAG laser beam welding without groove and filler metal. The weldment has been subjected to testings such as surface roughness, microstructure, hardness, tensile strength and distortion. Test results reveal that laser beam welding is very much suitable for joining Ti6Al4V/AA2024 alloys, while focusing from aluminium side.     

Mechanical Properties of Friction Stir Welded Cast Al–Mg–Sc Alloys

Friction Stir (FS) welding promises joints with low porosity, fine microstructures, and low vaporization of volatile elements compared with conventional welding techniques. FS weld was carried out on Vacuum Induction Melted 5?mm thick cast Aluminum?CMagnesium?CScandium (Al?CMg?CSc) alloy plates. Microstructural evaluation revealed that due to FS welding, fine and fragmented dynamically recrystallized grains have been formed in the weld nugget. Tensile fracture occurred out side the weld zone. The tensile strength of the welded joint is more than the cast base metal. The hardness of the FS welded joint is less than the hardness of the cast base metal. The minimum hardness was located on the retreating side of the weld. These results clearly show that FSW process is amenable to join cast Al?CMg?CSc alloy.     

Performance evaluation of 00Cr11NbTi perforated-plasma-arc-welded joint

Based on a 00Cr11NbTi ferritic stainless steel plate produced by Baosteel,the plasma arc welding was performed without filler wire.The mechanical properties of the welded joints were tested,as a result,the transverse tensile strength of the welded joints decreased to a certain extent in comparison with that of the base metal,but the bending performance and plasticity of the welded joint were good.     

高强铝合金的激光-MIG复合焊接的实验研究

以20mm厚的高强铝合金2519-T87为研究对象，研究了激光-MIG复合焊接工艺的工艺参数、坡口形貌以及热处理制度对高强铝合金的平板对接接头的抗拉强度的影响。研究表明：采用类似双U型坡口比国外常用的双V型坡口更有利于复合焊的焊接；保护气体对焊接接头的气孔的形成比较敏感，从而影响焊接接头的抗拉强度，复合焊的保护气体一般采用He气中添加少量的Ar；送丝速度通过改变焊接热输入来影响焊缝组织的晶粒大小以及强化元素的烧损量对焊接接头的强度影响较大。焊后对接头进行合适的热处理，可以显著提升接头的抗拉强度。     

Effect of heat input on microstructure and mechanical properties of dissimilar joints of AISI 316L steel and API X70 high-strength low-alloy steel

The microstructure and mechanical properties of dissimilar joints of AISI 316L austenitic stainless steel and API X70 high-strength low-alloy steel were investigated.For this purpose,gas tungsten arc welding(GTAW)was used in three different heat inputs,including 0.73,0.84,and 0.97 kJ/mm.The microstructural investigations of different zones including base metals,weld metal,heat-affected zones and interfaces were performed by optical microscopy and scanning electron microscopy.The mechanical properties were measured by microhardness,tensile and impact tests.It was found that with increasing heat input,the dendrite size and inter-dendritic spacing in the weld metal increased.Also,the amount of delta ferrite in the weld metal was reduced.Therefore,tensile strength and hardness were reduced and impact test energy was increased.The investigation of the interface between AISI 316L base metal and ER316L filler metal showed that increasing the heat input increases the size of austenite grains in the fusion boundary.A transition region was formed at the interface between API X70 steel and filler metals.     

Laser beam welding with filler metal

Laser beam welding generally does without the use of filler metal, in contrast to conventional welding processes. The use of filler metal in laser beam welding or in the combined GMA (g as-m etal-a rc) - laser beam - hybrid welding process widens the field of application for laser beam welding. The main advantages worthy of mention include, primarily, a greater weld gap bridging ability and a metallurgical influence on the weld metal. Based on the current state of knowledge, this article gives a few examples of different materials and material combinations the limited weldability of which is broadened when filler metal is used with laser beam welding. Listed as examples are low-alloy steels with partly elevated carbon contents, duplex steels, and the material combinations of steel/cast iron and austenite-ferrite joints. Besides laser beam welding with filler metal wire, examples of the combined GMA-laser hybrid welding process are also described.     

Effect of the Grain Size of the Initial Structure of 1565chM Alloy on the Structure and Properties of the Joints Fabricated by Friction Stir Welding

The effect of the initial grain size in the structure of the aluminum 1565chM alloy on the mechanical properties of the welded joints formed by friction stir welding and on the grain size in the weld core is studied. It is shown that the design of tool and, especially, the parameters of a screw groove exert a great effect on the grain size in the weld core.