6063铝合金焊接接头及部件大变形力学行为研究

本实验重点针对一类铝镁合金6063板件研究了熔化焊接头的不均匀大变形力学行为.利用微冲压试验结合有限元反向迭代计算对焊接接头中从焊缝到母材的不均匀力学性能进行了表征,获得不同微区内材料真应力应变关系.分析了焊接接头不均匀大变形演化规律.在此基础上对该类铝合金薄壁管件的轴向压缩行为进行试验和数值计算,讨论了结构参数、载荷条件等对焊接结构变形和断裂行为的影响.建立了接头的有限元计算模型.     

Microstructure and Mechanical Properties of Cold Metal Transfer Welding Similar and Dissimilar Aluminum Alloys

Integrating structures made from aluminum alloys in automotive industry requires a large amount of joining. As a consequence, the properties of the joints have a significant influence on the overall performance of the whole structure.Robot cold metal transfer welding is a relatively new joining technique and has been used in this work to join 6082-T4 and5182-O aluminum alloy sheets by using ER5356 and ER4043 filler metals. Microstructure characterization was performed by optical microscopy and energy dispersive X-ray spectroscopy, and the mechanical properties were measured by tensile and hardness tests. A correlation is made between welding variables, mechanical properties and the microstructure of welded joints. Results indicate that robot cold metal transfer welding provides good joint efficiency with high welding speed, good tensile strength, and ductility. Owing to the low heat input of robot cold metal transfer welding process, the heat affected zone microstructure was quite similar to base metals, and weld metal microstructure was the controlling factor of joint efficiency. The best performing were the 5182/5182 joints welded with ER5356 and these had mechanical property coefficients of 100%, 98%, and 85% for yield strength, ultimate tensile strength, and elongation, respectively.     

Microstructure and mechanical properties of laser beam welding 6061 aluminum alloy with different states

With the diversification of manufacture methods,joining the same materials with different states becomes indispensable in practical application.In present work,6061 aluminum alloys with different states were welded by laser beam welding (LBW).The microstructures of welded joint,before and after heat treating,were investigated.The mechanical properties,such as the tensile properties and microhardness,were tested.And the fracture characteristic was observed by means of scanning electron microscope (SEM).The results show that the 6061 aluminum alloys have superior weldability and the microstructures are different significantly in different states.Besides,the grain boundaries of the joint microstructures become unclear after the heat treating.The strength and the elongations of welded joints could reach to those of the base metal.The tensile fracture occurs in the fusion zone and near 6061-0 alloy.And the fracture presents ductile rupture.Therefore,the LBW is an effective method for 6061 aluminum alloy.     

高速列车用厚板铝合金CMT焊接工艺

针对低热输入、高质量焊接技术的需求,研究厚板铝合金多层多道冷金属过渡技术(cold matal transter,CMT)焊接工艺和脉冲MIG焊接工艺的区别,对CMT焊接和脉冲MIG焊接进行热循环曲线测量,焊接接头拉伸、弯曲、硬度等常规力学性能试验和接头微观组织分析.结果表明,铝合金厚板焊接时相对脉冲MIG焊接方法,CMT方法焊接温度场低,焊接接头软化明显减弱,冲击韧性得到提高,厚板多层多道焊接接头组织明显改善,晶粒明显细化.试验表明CMT焊接方法可获得相对脉冲焊接更加优良的铝合金焊接接头.     

热输入对7A52铝合金光纤激光焊接头组织及性能的影响

采用IPG公司生产的YLS-6000光纤激光器,对6 mm厚热轧态7A52铝合金进行焊接,研究不同焊接参数对接头组织及性能的影响。结果表明,焊缝中心为均匀分布的“雪花”状等轴晶,组织为α-Al+T(Mg3Zn3Al2),与母材相同,晶粒大小随热输入的增加而长大;随热输入增加,Mg,Zn元素的烧损逐渐加重;相同热输入下,高功率、高焊速能够降低Mg,Zn元素的烧损;母材硬度最高约为110 HV左右,焊缝中心硬度最低,硬度从焊缝中心向两侧母材呈“U”型分布;适当增大焊接热输入,接头的冲击吸收能量和抗拉强度均有所提高;在相同热输入情况下,高功率、高焊速的接头冲击性能降低,抗拉强度有所提高,最大抗拉强度为341 MPa,约为母材的69.8%,7A52铝合金光纤激光焊接头拉伸断口形貌呈韧-脆混合断裂。     

阳极氧化对超声波焊接6063铝合金与PPS的影响

为实现铝合金与塑料的有效连接,采用磷酸阳极氧化工艺对6063铝合金表面进行预处理,使用超声波金属焊接机对6063铝合金与聚苯硫醚(PPS)进行焊接.结果 表明:未经处理的6063铝合金与PPS超声波焊接接头抗剪强度随着焊接时间、焊接压力的增加先增大后减小,当焊接压力和焊接时间分别为0.5 MPa和6s时,可获得最大抗剪...     

The influence of artificial aging on the microstructure,mechanical properties,corrosion, and environmental cracking susceptibility of a 7075 friction-stir-weld

The influence of overaging to the T7451 temper on the microstructure, the mechanical properties, and the corrosion susceptibility of friction-stir-welded 7075 aluminum alloy was investigated by means of transmission electron microscope (TEM), SEM investigations, constant extension rate tests (CERT), alternate immersion tests, and potentiodynamic scans. The overaging that occurs during welding within the heat-affected zones of the friction-stir-welded 7075-O tempered plates promotes a slight formation of intragranular and grain boundary precipitates and increases the mechanical as well as the corrosion resistance properties as compared to the T7451 welded plates. The “double” overaging treatment, consisting of the T7451 temper and the thermal transient experienced by the heat-affected zones of the 7075-T7451 welded plates, increases the size of the intragranular and the grain boundary precipitates as well as the precipitate-free zones. These facts decrease the mechanical and corrosion properties of the 7075-T7451 weld. The T7451 thermal treatment applied after the welding of the 7075-O plates promotes the high presence of small precipitates and reduces the size of the precipitate-free zones. This fact increases the general corrosion resistance, but decreases the mechanical properties. Therefore, the corrosion as well as the mechanical properties are greatly correlated with minute changes in the microstructure, which can arise by short-term heat exposure as for instance during welding. It was also found that the environmental susceptibility measured by means of CERTs may be influenced by “solution-strengthening” corrosion mechanisms which increase the strain. This fact is present in weld microzones particularly susceptible to corrosion.     

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。     

The effect of material arrangement on mechanical properties in Friction Stir Welded dissimilar A5052/A5J32 aluminum alloys

The joining of dissimilar A5052 and A5J32 alloy sheets with thicknesses of 1.5mm and 1.6mm, respectively, was carried out using the Friction Stir Welding (FSW) technique. The tool rotated at a speed in a range of 1000 rpm to 1500 rpm with a welding speed ranging from 100 mm/min to 400 mm/min. The hardness and tensile properties of the friction stir welded A5052/A5J32 joint were investigated according to the fixing location. In the case where the A5J32 aluminum alloy was fixed on the retreating side, defect-free welds were obtained under all welding conditions. However, in the case where the A5052 aluminum alloy was fixed on the retreating side, some welding defects were observed at the joint under certain welding conditions with a lower heat input. However, the welding defects had no effect on the mechanical properties. A good correlation between the hardness distribution and the welding zones was observed. The experimental results showed that the tensile properties differed depending on the fixing location of the materials and were also affected by the welding conditions.     

NUMERICAL ANALYSIS ON THE RESIDUAL DISTORTION OF Al ALLOY SHEET AFTER FRICTION STIR WELDING

大尺寸6056铝合金薄板经过搅拌摩擦焊接实验后出现了严重的面外变形,虽然变形程度小于熔化焊结果, 但已经影响到被焊薄 板的装配和使用.为详细研究和预测铝合金薄板在搅拌摩擦焊后的残余变形, 以焊接实验条件为基础, 建立了搅拌摩擦焊接三维有限元 热力耦合分析模型. 模型中涉及了利用搅拌头工作转矩计算热输入量、工件和卡具之间的接触热传导、随温度变化的材料模型, 以及综合 考虑搅拌头机械作用等工作.利用该模型可以得到不对称的纵向残余应力结果, 残余变形的趋势在整块板上都与实验结果相同, 而且变形量和实验测量值之间的误差在20%以内.     

6063铝合金TIG焊接头的变形行为及等效模型

用有限元软件ABAQUS对平板对接6063铝合金TIG焊接头进行拉伸模拟,研究了HAZ宽度及板厚对焊接接头变形的影响规律,进而建立TIG焊接头有限元等效模型,并用带焊缝的6063铝合金薄壁方管的压缩模拟来验证等效模型的精确性.结果表明,与母材相比,力学性能不均匀的焊接接头中应力状态较为复杂,三向应力度在母材与HAZ交界处和焊缝与HAZ交界处存在突变,三向应力度最大值的位置从母材与HAZ交界处转变为焊缝与HAZ的交界处;力学性能不均匀的焊接接头中的三向应力度不仅取决于试样的厚度,还取决于接头的几何尺寸;铝合金TIG焊接头有限元等效模型宽度为20 mm;带焊缝铝合金薄壁方管的精细模型和等效模型的载荷-位移曲线吻合较好.     

基于ANN的TA15钛合金TIG焊接头拉伸性能模型建立

近α型钛合金TAI5具有较好的综合力学性能,在飞机结构中有广阔的应用前景。针对TAI5钛合金进行了系统的TIG焊试验,并进行了焊接接头拉伸性能测试。在此基础上,基于人工神经网络（ANN）原理对影响TAI5钛合金TIG焊接头拉伸性能的主要参数进行了选取,确定ANN的输入和输出参数,建立了TAI5钛合金TIG焊接头拉伸性能ANN模型并对模型进行了优化及误差分析。结果表明,最终建立的拉伸性能模型能很好地适用于TAI5钛合金TIG焊接头拉伸性能的模拟,优于传统回归方法。     

On the growth of intermetallic phases by heat treatment of friction stir welded aluminum steel joints

Multi-material components made from aluminum and steel sheet metal are an innovative approach for weight reduction in automotive applications. However, lightweight components made from aluminum and steel require suitable joining technologies. A promising solid-state welding technology for producing dissimilar steel aluminum joints is Friction Stir Welding, which minimizes the formation of Fe-Al intermetallic phases due to process temperatures lower than the melting temperatures of the base material. The results obtained show a comparison of steel aluminum joints made by FSW using DC04 mild steel with the strain hardened aluminum alloy AA5754-H22 on the one hand and the precipitation hardened aluminum alloy AA6082-T6 on the other hand. The difference between achieved maximum tensile strengths of the joints in relation to those from both base materials is investigated. Due to the stirring and heat input of the welding process, the temper condition of the precipitation hardened aluminum alloy is changed. To improve the mechanical properties of the welded joints, post weld heat treatments are performed. The post weld heat treatments of the produced multi-material specimens from AA6082-T6 aluminum alloy and mild steel at various heat treatment conditions show substantial growth of intermetallic phase layer, which is characterized in detail within the present work. Tensile tests show a degradation of the mechanical properties resulting in a decreased tensile strength and insufficient connection of both materials. Investigations using a scanning electron microscope (SEM) show a distinct increase of the thickness of intermetallic phases in the transition between aluminum and steel.     

焊丝成分对6082-T6铝合金焊接接头组织和性能的影响

采用ER5356和ER5087焊丝对12mm厚6082-T6铝合金进行熔化极惰性气体保护焊(MIG)后,通过显微硬度测试、拉伸力学性能测试、光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM)等研究焊丝成分对焊接接头力学性能与显微组织的影响。结果表明:采用ER5087焊丝焊接的6082-T6铝合金焊接接头焊缝区晶粒更细小;抗拉强度、屈服强度、断后伸长率以及焊接系数均高于ER5356焊丝焊接的6082-T6铝合金焊接接头的;两种焊丝焊接的6082-T6铝合金焊接接头的硬度最低区域与拉伸断裂位置均在距离焊缝中心10～15mm处的热影响区,该区域β″强化相聚集长大、粗化,导致析出相强化作用减弱,成为焊接接头性能最薄弱区域。     

铝合金多股复合焊丝脉冲MIG焊接接头组织与性能分析

选用铝合金多股复合焊丝对5A06板材进行脉冲MIG对接焊接,并与传统单丝TIG焊接接头的组织与性能进行对比.结果表明,采用铝合金多股复合焊丝脉冲MIG焊时,焊接接头的抗拉强度最大可达340 MPa （为母材强度的86.7%）.MIG焊接接头性能与TIG焊相比差异较小,但MIG焊可以提高焊接效率约4倍.焊接接头热影响区的软化主要受较高的热输入导致的晶粒尺寸增加、再结晶比例较大以及析出相的粗化和减少影响,而采用铝合金多股复合焊丝脉冲MIG焊能够降低焊接过程的热输入,细化晶粒,减弱MIG焊接接头中Mg元素的烧损和析出物的减少,达到控制焊接接头软化的目的.     

Effects of Heat Input on Microstructure and Mechanical Properties of Laser-Welded Mg-Rare Earth Alloy

The effects of heat input on the quality of laser-welded Mg-rare earth alloy NZ30K were studied. Using a 15-kW high-power CO₂ laser, the microstructure and mechanical properties of welded joints under different heat inputs had been analyzed and tested. It is found that the welding heat input plays an important role in laser welding of NZ30K. Good welded joint without macroscopic defects can be obtained using the proper heat input. With the increasing heat input, welding penetration gets deeper, the width of the heat-affected-zone becomes larger, and the distribution of precipitates changes concentration. Tensile tests display that the ultimate tensile strength (UTS) of the welded joint tends to increase at first with the increasing heat input. After the welded joint gets full penetration, the UTS remains almost the same, although the heat input is increased.     

扩散焊工艺对6063铝合金焊接接头性能的影响

分别采用固相扩散焊和瞬间液相扩散焊方法焊接6063铝合金。采用金相显微镜对扩散界面附近的显微组织进行了分析;采用万能试验机测试了焊接接头的抗拉强度。试验结果表明,在连接同种铝合金材料的情况下,固相扩散焊相比瞬间液相扩散焊能够获得更为良好的接头性能。在焊接温度540℃、焊接压力8 MPa、保温时间80 min时,固相扩散焊接头区域成分均匀,没有空洞等缺陷,抗拉强度为122 MPa,达到同种热处理条件下母材抗拉强度(130 MPa)的94%。     

Mechanical properties of welded joints in thin walled aluminium extrusions

Abstract

The present work describes the tensile properties of weldments in thin walled extruded Al–Mg–Si alloys. Tungsten inert gas (TIG), metal inert gas (MIG), and friction stir (FS) welding are considered. Properties of joints welded with different filler metals are presented, both matching and undermatching the parent materials in strength. The weldments were tested in both as welded and post-weld aged conditions. It is shown that silicon rich filler metals (Al–5Si and Al–12Si) were adequate for the welding of 6063 alloy but did not give welds with strength sufficient to match that of 6082 alloy. Tungsten inert gas welding resulted in large heat affected zone (HAZ) widths of 20 mm, compared with HAZ widths of 10 and 8 mm for MIG and FS welding respectively. This relationship was also seen in tensile tests where FS specimens exhibited the highest strength and TIG specimens exhibited the lowest strength. The post-weld aged materials recovered some strength, with increases in tensile strength of 10–15% for 6063 alloy and of 20% for alloy 6082 compared with the strengths of the as welded specimens. Comparisons between experimental data and two design codes, a draft European standard and the British standard BS 8118, show that the European standard is conservative for welds in thin walled material. Standard BS 8118 describes MIG and FS HAZ widths well but underestimates the HAZ width for TIG welds.     

几种铝钢异种金属熔钎焊工艺的对比与分析

采用脉冲旁路耦合电弧MIG焊、CMT及激光焊方法实现铝/镀锌钢板搭接焊,对焊缝界面微观组织、形貌及元素成分进行了观察分析,并测试了其力学性能.结果表明,三种焊接方法均可以实现铝/镀锌钢板异种金属的优质连接,获得成形良好的焊缝,搭接接头的抗拉剪强度均可以达到铝合金母材的80%以上,拉伸试样断裂在焊缝铝合金母材热影响区.当母材热输入及工艺合适时,三种方法下搭接接头界面处均形成一主要成分为Fe₂Al₅和FeAl₃,平均厚度约为8 μm的金属间化合物,而且控制金属间化合物的生成是获得铝/钢焊接优质接头的关键.     

2219铝合金直流正极性A-TIG焊接技术

提出了一种用于2219铝合金焊接的新方法,焊前在待焊表面预先涂敷一层除气去膜活性剂,实现了2219铝合金的直流正极性焊接. 研究不同的活性剂浓度对2219铝合金直流正极性活性TIG焊(A-TIG)焊缝表面成形、气孔缺陷、微观组织以及力学性能的影响. 结果表明,当活性剂浓度为10%时可以获得无气孔缺陷、表面成形和力学性能良好的2219铝合金直流A-TIG焊缝. 与变极性TIG焊相比,焊接过程电弧稳定性好,热输入小,焊缝质量优异.