镍中间层对铝/镁异种金属搅拌摩擦焊接头微观组织的影响

采用搅拌摩擦焊(friction stir welding, FSW),引入厚度为0.05 mm镍箔作为中间层,在焊接速度不变条件下,采用不同转速对厚度为4 mm的6061铝合金和AZ31镁合金进行平板对接,对接头进行系列微观组织表征及力学性能测试,探讨转速对接头中镍颗粒分布状态,金属间化合物(intermetallic compounds, IMCs)种类与分布及接头强度的影响规律. 研究结果表明:与未引入中间层接头相比,引入镍改变了铝/镁异种金属FSW接头焊核区(weld nugget zone, WNZ)中IMCs种类及分布,WNZ存在明显的镁合金与铝合金相间的带状组织,其上分布着絮状Al₁₂Mg₁₇、颗粒状Mg₂Ni、层状Al₃Mg₂及大小不一的镍箔颗粒;随着转速增加,镍箔颗粒分布愈加均匀,Al₃Mg₂数量相对减少,且脆性Al₃Mg₂由连续分布逐渐演变为断续分布;当转速为750 r/min时,接头抗拉强度达到最大值,与未引入中间层接头相比,引入镍中间层接头抗拉强度提高了56 MPa,达到镁合金的56.9%.     

Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample’s mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.     

Influence of Pin Offset on Microstructure and Mechanical Properties of Friction Stir Welded Mg/Ti Dissimilar Alloys

The influences of pin offset on the formation, microstructure and mechanical properties of friction stir welded joint of Ti6 Al4 V and AZ31 B Mg dissimilar alloys were investigated. The results show that sound joints are obtained at different offsets. With the offset decreasing from 2.5 to 2.1 mm, the number of Ti alloy fragments is increased, and the stir zone(SZ) is enlarged and the grains in SZ become coarser. A hook-like structure is formed at the Mg/Ti interface and its length is increased with the decrease in pin offset. The Al element has an enrichment trend at the Ti alloy side near the Mg/Ti interface when the offset is decreased, which is beneficial to the bonding of the interface. An Al-rich layer with a thickness of 3–5μm forms at the offset of 2.1 mm. All the joints fracture at the interface and present a mixed ductile-and-brittle fracture mode. The joint tensile strength is increased with the offset decreasing from 2.5 to 2.1 mm, and the maximum tensile strength of 175 MPa is acquired at the offset of 2.1 mm.     

C18000铜合金搅拌摩擦焊接头微观组织与性能

对3.5 mm厚的C18000铜合金板进行搅拌摩擦焊焊接试验. 在焊接速度120 mm/min,转速1 200 r/min工艺下获得无缺陷焊接接头. 在金相显微镜下对接头的宏观形貌、微观组织进行观察,用扫描电镜和透射电镜对母材和搅拌区组织进行观察分析. 结果表明,接头区大致分为母材区、热影响区、热力影响区和搅拌区,搅拌区晶粒细小均匀,热力影响区晶粒沿边界切线方向被拉长;搅拌区Cr₃Si相部分溶解,搅拌区组织中的Cr单质相和Ni₂Si相溶解导致接头硬度和抗拉强度下降. 搅拌区平均硬度为151.4 HV;接头抗拉强度为497 MPa,达到母材的72%;接头电导率下降为35%IACS.     

基于Ti中间层的AZ31镁合金/6061铝合金电阻点焊研究

通过添加钛箔中间层,研究了镁/铝合金异种金属电阻搭接接头的微观组织与力学性能。研究结果表明,添加0.2mm厚度钛箔中间层可以大幅提高镁/铝异种金属电阻点焊接头的结合强度,接头的最大拉剪力随焊接电流的增大先增大后减小;当焊接电流为14kA时,最大拉剪力达到最大为2.2kN。铝钛界面处有TiAl₃生成,接头断裂在镁侧热影响区上,经过换算接头的剪切强度能够达到156MPa。通过SEM和EDS分析,添加钛中间层阻断了镁合金和铝合金的相互扩散,钛中间层阻碍了Mg-Al金属间化合物的生成,从而大大提高接头的结合强度。     

Ti(C,N)/40Cr钎焊接头残余应力数值计算

使用有限元法模拟计算了Cu箔、Mo箔对缓解Ti(C,N)/40Cr钎焊接头残余应力的效果.结果表明,无缓冲层直接钎焊,在Ti(C,N)金属陶瓷外侧靠近钎缝的狭小区域内产生较高的拉伸残余应力,其峰值达到268 MPa;使用屈服极限低的Cu箔,接头最大残余拉应力下降到98 MPa,缓解应力效果显著,但最大残余拉应力所处区域与无缓冲层相比没有明显变化;使用线膨胀系数小的Mo箔,应力峰值出现在Mo箔中,同时缓解应力效果不如Cu箔;无论使用Cu箔还是Mo箔,最佳厚度约为0.8 mm左右,大于或小于该厚度值,应力得不到有效释放.     

Influence of tool pin design on properties of dissimilar copper to aluminum friction stir welding

Dissimilar friction stir welding (FSW) of copper and aluminum was investigated by nine different tool designs, while the rest of the process parameters were kept constant. Mechanical and metallurgical tests such as macrostructure, microstructure, tensile test, hardness, scanning electron microscope and electron X-ray spectrographs were performed to assess the properties of dissimilar joints. The results exhibited that, the maximum joint strength was achieved by the tool of cylindrical pin profile having 8 mm pin diameter. Besides, the fragmental defects increased as the number of polygonal edges decreased, hence the polygonal pin profiles were unsuitable for dissimilar FSW butt joints. Furthermore, the tensile strength increased as the number of polygonal edges increased. Stir zone of polygonal pin profiles was hard and brittle relative to cylindrical tool pin profiles for same shoulder surface. Maximum hardness of HV 283 was obtained at weld made by the polygonal square pin profile. The hard and brittle intermetallic compounds (IMCs) were prominently presented in the stir zone. Phases of IMCs such as CuAl, CuAl₂, Cu₃Al and Cu₉Al₄ were presented in the stir zone of dissimilar Cu–Al joints.     

高镁铝合金搅拌摩擦交叉焊接头微观组织与力学性能

为满足大型铝合金船舶壁板的制造需求,对新一代高镁铝合金进行了搅拌摩擦交叉焊接试验. 结果表明,交叉焊接头成形良好,搅拌区晶粒尺寸最小,热力影响区晶粒形态没有明显方向性,与单道搅拌摩擦焊相比,交叉焊接头搅拌区晶粒组织更细. 显微硬度测试结果表明,交叉焊接头显微硬度变化范围较小,前进侧接头软化明显;拉伸试验测试结果表明,交叉焊接头抗拉强度为340 MPa,为母材强度的87%,对比搅拌摩擦焊接头抗拉强度358 MPa略微降低,在热影响区断裂,断裂方式为45°韧性断裂;疲劳裂纹萌生于焊缝底部,在最大应力150 MPa下循环超2 × 106次未断裂,疲劳性能良好,瞬断区断裂方式为韧性断裂.     

静轴肩辅助铝镁搅拌摩擦搭接接头的组织与性能

文中将静止轴肩技术应用到铝镁异种合金的搅拌摩擦搭接过程中,并分析了焊接速度对接头成形和力学性能的影响.结果表明,静止轴肩能够增强上下板之间的材料交换,焊后搅拌区呈较大的洋葱环形貌,其内部分布大量的金属间化合物;搭接面处发生良好的冶金结合.由于生成金属间化合物,洋葱环区域的显微硬度值明显高于接头其它区域.X射线衍射结果表明,金属间化合物的主要成分是Al₃Mg₂和Al₁₂Mg₁₇.接头的抗拉强度随着焊接速度的增加呈先上升后下降的趋势,最大值在焊接速度为40 mm/min时取得.     

高碳钢片对铝硅镀层热成形钢激光焊接接头组织性能的影响

以45号碳钢薄片为夹层,利用CWX3000光纤激光器对1.5 mm厚的铝硅镀层热成形钢进行激光焊接试验,研究焊缝碳含量对焊接接头显微组织和力学性能的影响. 试验结果表明,碳钢薄片的加入使焊缝碳含量增加,奥氏体相区扩大,焊缝δ铁素体的体积分数由17.3%降低至4.5%,焊缝平均硬度由425 HV增加至557 HV,焊接接头的抗拉强度由980 MPa增加至1 280 MPa,杯突值由1.7 mm增加至3.2 mm,抗拉强度及成形性能均有所提升.     

焊接速度对BT-FSW 2219铝合金接头流动行为及组织与力学性能影响分析

以4 mm厚2219-T87铝合金为研究对象,采用数值模拟和试验研究相结合的方法,研究了焊接速度对双轴肩搅拌摩擦焊接(BT-FSW)过程中金属流动行为、接头组织特征和力学性能的影响. 模拟结果表明,随着焊接速度增加,焊缝高温区逐渐变窄,轴肩附近的材料流动减弱,而搅拌针附近的材料流动增强. 试验结果表明,随着焊接速度增加,材料汇流区及S线缺陷均向前进侧(AS)靠近,焊接速度过大时AS附近的搅拌区(SZ)形成不连续组织. 接头SZ的硬度值随着焊接速度增加而增大,而拉伸强度先增大后稍降低. 当转速为300 r/min,焊接速度为150 mm/min时,接头获得最大的拉伸强度,为414 MPa ± 4MPa.     

基于Ti中间层的SiCp/6061-T6Al MMCs低功率激光-TIG复合焊组织与性能

以0.1mm厚的Ti箔做中间夹层,使用低功率激光-TIG复合焊的方式对SiCp/6061-T6Al MMCs 进行焊接,并对接头的宏观形貌、显微组织、物相、电阻率、抗拉强度及断口形貌进行分析。结果表明：激光功率对焊缝的成形有着较大影响;Ti箔的加入基本抑制了焊缝中针状Al₄C₃生成,并生成TiC增强相以及条状TiAl₃;焊缝区为等轴晶组织,熔合区为柱状晶组织,热影响区组织变化不明显;随着激光功率的增加接头的电阻率呈现出增加的趋势,并明显高于母材;在554W时接头的抗拉强度可达196.98MPa,是母材强度的54.71%。接头断口中几乎没有气孔,韧窝中的第二相粒子以TiC为主,接头呈现出以脆性断裂为主的脆-韧性混合断裂特征。     

搅拌摩擦焊修复ZL210铸造铝合金组织与性能分析

鉴于铸件中存在不可避免的缺陷,以ZL210合金为研究对象,对搅拌摩擦焊修复技术进行试验研究,重点分析转速对修复接头微观形貌和力学性能的影响. 结果表明,当转速过低时,修复区容易出现孔洞缺陷;在合理的焊接参数组合下可得到无缺陷的焊核区,其由细小的等轴晶组成. 修复区的显微硬度呈“W”分布,热影响区的宽度随转速增加而增加. 另外,随着转速的增加,修复区的抗拉强度先增加后减小;当转速为1 500 r/min,修复区的抗拉强度和断后伸长率达到最大值,分别为318 MPa和11.8%. 断裂形貌表明修复后材料呈现典型的韧性断裂.     

Effect of laser offset on microstructure and mechanical properties of laser welding of pure molybdenum to stainless steel

Direct welding of Mo and stainless steel is exceptionally difficult due to intrinsic brittleness of Mo and the formation of brittle Fe-Mo phases. To explore the feasibility of welding of Mo and stainless steel, the laser offset method was used in this study. Experimental results show that the offset of the laser beam toward stainless steel has a positive effect for the quality of Mo/Fe dissimilar joint. As the laser beam shifts from the Mo side to the stainless steel side, the formation of welding defects and Fe-Mo intermetallic compounds (IMCs) are effectively restricted because of the decrease amount of molten Mo. The decrease of Fe-Mo IMCs contributes to the reduction of hardness in the joints. With an increase of laser offset, the thickness of Fe-Mo IMCs layer decreased, consequently the tensile strength of joints increased first and then decreased in the laser offset range of 0.2–0.5 mm. The highest tensile strength of the joints is 290 MPa at the laser offset of 0.3 mm. All joints failed in the Fe-Mo IMCs layer with brittle fracture mode during tensile tests, indicating the weakest zone of the joint was Fe-Mo IMCs layer. A sound weld of Mo and stainless steel can be obtained if an appropriate thickness of Fe-Mo IMCs layer is produced by adjusting the laser offset.     

Effect of process parameters on microstructure and properties of laser welded joints of aluminum/steel with Ni/Cu interlayer

The effects of laser parameters and interlayer material on the microstructure and properties of the welded joint between 6061 aluminum alloy and stainless steel were studied. The results show that the density and microstructure of the welded joint can be optimized by changing the laser power with 0.05 mm Cu foil and 0.1 mm Ni foil as interlayer. A large number of new Cu–Al binary phases were found near the aluminum alloy, which effectively inhibited the formation of the binary brittle phase of Fe–Al. The maximum shear force of 1350.96 N was obtained with laser power of 2200 W. The shear force of the welded joint increased to 1754.73 N when the thickness of the Cu foil thickness changed to 0.02 mm.     

Nb、Cu金属层厚度对Si3N4/Nb/Cu/Ni/Incone l600接头组织和性能的影响

采用Nb／Cu／Ni作中间层，在连接温度为1403K、连接时间为50min、连接压力为7．5MPa的条件下，采用不同尺寸的中间层进行了Si3N4陶瓷与Inconel 600高温合金的部分液相扩散连接。通过改变Nb层、Cu层厚度，研究了Cu层、Nb层厚度变化对Si3N4／Nb／Cu／Ni／Inconel 600接头的组织和性能的影响。研究发现，当Cu层厚度小于0．05mm时，随着Cu层厚度的增加，接头中的Cu—Ni合金层厚度增加，接头强度快速增加；当Cu层厚度超过0．05mm时，接头中的Cu—Ni合金层厚度由于压力的作用不明显增加，接头强度增加缓慢。随着Nb层厚度的增加，反应层厚度增加，接头的强度先增大后减小。     

中间层材料对Ti/Al异种金属搅拌摩擦焊组织性能影响

以3mm厚2A14铝合金和TC4钛合金为试验材料,分别添加0.05mmZn和Ni箔片,研究了不同工艺参数下Zn和Ni对接头微观组织、力学性能的影响。试验结果表明：当添加中间层Zn时,在旋转速度为375r/min、焊接速度为75mm/min时,接头抗拉强度达到最大值237.3MPa,为铝合金母材拉伸强度的56.7%。同样参数下,添加中间层Ni后,能显著减少接头中脆性相TiAl₃,接头抗拉强度最大值提高到285.3MPa,达到铝合金母材抗拉强度的68％,接头断裂方式呈脆性+韧性混合型断裂。     

Friction stir butt welding of A5052-O aluminum alloy plates

Friction stir butt welding (FSW) between A5052-O aluminum alloy plates with a thickness of 2 mm was performed.The rotation speeds of the welding tool were 2000 and 3000 r/min,respectively.The traverse speed was ranged from 100 mm/min to 900 mm/min.The defect-free welds with the very smooth surface morphology were successfully obtained,except for at the welding condition of 3000 r/min and 100 mm/min.The onion ring structure was observed in the friction-stir-welded zone (SZ) at the condition of 2000 r/min and 100 mm/min.For all the welding conditions,the grain size of the SZ was smaller than that of the base metal,and was decreased with the decrease of the tool rotation speed and with the increase of the tool traverse speed.The stir zone exhibited higher average hardness than the base metal.The decrease of the tool rotation speed and the increase of the tool traverse speed resulted in the increase in the average hardness of the SZ.The tensile strength of the FSWed plates was similar to that of the base metal,except for at the welding condition of 3000 r/min and 100 mm/min.The total elongation of the FSWed plates was lower than that of the base metal.     

6063铝合金双轴肩搅拌摩擦焊接头组织性能研究

进行了3 mm厚6063-T4铝合金双轴肩搅拌摩擦焊接。结果表明,当搅拌头转速为600 r/min,焊速在100~300 mm/min的范围内,可获得表面成形美观、内部无缺陷的优质接头。在接头搅拌区内,上、中、下各层硬度分布较为均匀,在热机影响区及热影响区内,上、下层硬度值高于中间层。热机影响区靠近搅拌区的位置以及热机影响区与热影响区的交界处为接头的两个薄弱位置。随着焊接速度的增加,接头各区域硬度值以及抗拉强度有着先增大后减小的趋势,所得最优接头抗拉强度为174 MPa,达到母材的87%,断裂位置位于热影响区。     

Friction welding of TiAl intermetallics and structural steel by applying Inconel 718 as interlayer

0IntroductionInterlayer metal is usually introduced while solidwelding heterogeneous metals with different chemical com-ponents and microstructures[1-3].The diffusion activationenergy(DAE)in both sides of interlayer and base metalcould be affected by the …