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 …     

铝/铜异种金属电阻热辅助超声波缝焊工艺特性

1060纯铝箔作为中间层,通过电阻热辅助超声波缝焊的方式实现1 mm厚度6061铝合金和T2紫铜异种金属焊接,分析了焊接过程中电阻热对铝/铜焊接接头焊缝成形、界面形貌、温度场以及力学性能的影响. 结果表明,采用单独超声波缝焊焊接铝/铜异种金属时,因产生的焊接能量较小,接头连接界面处仅局部区域位置形成连接,接头拉剪强度为45 MPa. 但在电阻热辅助超声波缝焊过程中,电阻热的加入能够有效预热工件,令待焊材料表面发生软化,在高频振动作用下,接头连接界面处形成有效连接. 同时,引入电阻热提高了铝/铜界面处温度,由单独超声波缝焊的140 ℃增加至190 ℃,界面处原子扩散距离增加,获得焊接接头的拉剪强度增加至75 MPa,相对前者接头拉剪强度提高67%.     

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。     

Improvement of joint strength in dissimilar friction welding of Ti-6Al-4V alloy to type-718 nickel-based alloy using the Au–Ni interlayer

ABSTRACT

An Au–Ni interlayer was used to improve the joint strength between the Ti-6Al-4V alloy friction welded to the 718 Ni-based alloy. The interlayer was melted and ejected at the interface of the joint during friction welding, showing that frictional heat played a role in brazing of the interlayer. The melted interlayer suppressed the formation of intermetallic compounds between titanium and nickel at the interface. The tensile strength of the joint significantly increased from 460?MPa for direct friction-welded joints, to 698?MPa when the interlayer was added. The mechanism underlying the strength improvement of the friction-welded joint was the unique phenomenon of a combination of brazing of the interlayer and diffusion of solutes in the base metal to the interlayer.     

Friction welding of pure titanium and pure nickel

Abstract

The joint tensile strength and metallurgical properties of a friction welded joint of commercially pure Ti and pure Ni has been investigated in as welded and post-weld heat treated conditions. While friction pressure did not significantly impinge on joint tensile strength, joint tensile strength was affected by friction time. A 1–1·5 μm thick interlayer is essential to join pure Ti and pure Ni using friction welding. A maximum joint tensile strength of 450 MPa was achieved and the joint fractured in the Ti original (not heat affected zone) substrate, i.e. the joint efficiency was approximately 112% relative to Ti substrate and 94·5% relative to Ni substrate. The joint tensile strength abruptly decreased as heating temperature was increased to 873 K and/or the Larson-Miller parameter was increased to approximately 19–20 × 10³. The joint tensile strength rapidly decreased with increasing interlayer thickness up to approximately 10 μm, and then remained constant for further increase in interlayer thickness. Four layers occurred at the interface of joints heated to more than 873 K, namely Ti₂Ni, TiNi, TiNi₂, TiNi₃. The fracture of heated joints propagated mainly in the Ti₂Ni layer and/or at the interface between the TiNi and TiNi₃ layers.     

TiAl金属间化合物电子束焊接头应力场分布特征

采用热弹塑性有限元方法,对TiAl金属间化合物平板电子束焊接接头的焊接应力进行了三维数值模拟,并分析了应力分布状态与裂纹特征之间的关系.结果表明,沿焊缝方向σx为残余拉应力,在焊道中部维持在较高水平,最高拉应力为390MPa.焊道中部横截面σx方向为残余拉应力,在热影响区附近达到最大值415 MPa,σy方向也为残余拉应力,且在距焊缝中心1.9 mm处达到最高值160 MPa左右.在不同焊接热输入条件下接头最高抗拉强度为304.7 MPa,断裂发生在接头热影响区附近,即残余应力最大的区域.     

Effects of Insert Metal Type on Interfacial Microstructure During Dissimilar Joining of TiAl Alloy to SCM440 by Friction Welding

Although the welding zone of direct bonding between a TiAl alloy and SCM440 can be obtained by friction welding, martensitic transformation and the formation of intermetallic compounds (IMCs) and cracks result in a lower tensile strength of the joints relative to those of other welding techniques. Insert metals were used as a buffer layer to relieve stress while increasing the bond strength. In this study, the microstructure and mechanical properties on welded joints of a TiAl alloy and SCM440 with various insert metals, were investigated. The TiAl/Cu/SCM440 and TiAl/Ni/SCM440 joints were fabricated using a servo-motor-type friction welding machine. As a result, it was confirmed that the formation of a welding flash was dependent on the insert metal type, and the strength of the base metal. At the TiAl/Cu/SCM440 interface, the formation of IMCs CuTiAl and Cu₂TiAl was observed at TiAl/Cu, while no IMC formation was observed at Cu/SCM440. On the other hand, at the TiAl/Ni/SCM440 interface, several IMCs with more than 100 μm thickness were found, and roughly two compositions, viz., Ti₂NiAl₃ and TiNi₂Al, were observed at the TiAl/Ni interface. At the Ni/SCM440 interface, 10 μm-thick FeNi and others were found.     

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。     

镀锌钢一6016铝合金异种金属加入中间夹层铅的激光焊接

对1．2mm厚镀锌钢板和1．15mm厚6016铝合金平板试件进行了加入中间夹层铅的激光搭接焊试验,通过调整焊接工艺参数获得最佳焊接成形,利用卧式金相显微镜、扫描电镜、x射线衍射、微机控制电子万能试验机等手段研究了焊接接头各区域的金相组织、断口形貌、主要物相与接头力学性能．结果表明,在钢／铝激光焊中添加中间夹层铅,焊接接...     

DP780镀锌钢激光焊接性能与工艺

针对0.8 mm的车用DP780镀锌双相钢,采用4 kW的连续光纤激光器对材料进行激光搭接试验,通过调节两板间的预留间隙、激光功率、焊接速度、离焦量,研究了工艺参数对焊接接头焊缝的成形影响规律,同时分析各工艺参数对焊缝下塌量、抗拉强度、气孔状况的影响规律;最后基于焊缝抗拉强度、焊缝下塌量以及焊接过程中气孔状况评价焊接质量.结果表明,功率在3 800 W、焊接速度在95~100 mm/s,离焦量在-2~2 mm,预留间隙在0.2~0.25 mm区间的工艺参数条件下,焊接成形较好,此时的抗拉强度保持在180 MPa以上,下塌量总量在0.35~0.45 mm,以及飞溅和外部气孔较少.建立抗拉强度—焊缝下塌量—气孔状况方法评价焊接质量,采用此方法,能够改善气孔缺陷,提升焊接效率.     

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.     

CO_2激光焊接600MPa DP钢接头组织与性能

采用CO2激光对抗拉强度为600MPa,厚度1.4mm的DP钢进行焊接.研究焊接速度对焊缝外观和截面成形的影响、接头的组织特点、硬度、强度和成形能力.结果表明,激光功率相同,焊接速度较低时焊缝易产生气孔,焊接速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝区组织主要由马氏体构成,从焊缝、焊接热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝出现马氏体组织,接头的塑性和韧性降低,板材的冲压成形能力下降.     

Improving Joint Morphologies and Tensile Strength of Al/Mg Dissimilar Alloys Friction Stir Lap Welding by Changing Zn Interlayer Thickness

The pure Zn foils with different thicknesses(0.02, 0.05, 0.1, 0.2 and 0.3 mm) were selected as interlayers to improve the quality of friction stir lap welding joint of 7075-T6 Al and AZ31 B Mg dissimilar alloys. The effects of the interlayer thickness on joint formation, microstructure and tensile strength were analyzed. The results displayed that the maximum length of the boundary between stir zone(SZ) and thermo-mechanically affected zone in lower plate was obtained by the addition of the Zn interlayer with 0.05 mm thickness. The Mg–Zn intermetallic compounds(IMCs) were discontinuously distributed in the SZ, replacing the continuous Al–Mg IMCs. The size of Mg–Zn IMCs increased with the increase in the thickness of the Zn interlayer. The maximum tensile shear strength of 276 N mm-1 was obtained by the addition of 0.05 mm Zn foil, which increased by 45.6% of that of the joint without the Zn foil addition.     

Nd:YAG激光焊接800 MPa TRIP钢的接头组织与性能

采用Nd:YAG激光对强度为800MPa,厚度为1.2mm的TRIP钢板进行焊接.研究焊接速度对焊缝外观和截面成形的影响及接头的组织特点、硬度、强度和成形能力.激光功率相同,焊接速度较低时焊缝易产生气孔,速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝组织主要由马氏体构成,从焊缝、热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝中出现马氏体,接头的塑性和韧性降低,板材的冲压成形能力下降.     

基于试验设计与统计分析的双相钢激光焊工艺优化

为了优化激光焊接接头力学性能,利用试验设计方法对厚度为1.7 mm的DP600双相钢进行对接焊接试验,采用回归分析得到了激光焊接功率、焊接速度、离焦量、侧吹保护气体流量与接头抗拉强度之间的数学模型. 分析了焊接速度与侧吹气流量对焊缝抗拉强度的交互影响作用. 通过遗传算法优化该模型并得到了最优的焊接工艺参数组合,当焊接功率为1.7 kW,焊接速度为25 mm/s,侧吹气流量为2.4 m3/h,离焦量为-1 mm时焊缝的抗拉强度最大. 验证试验所测的焊缝抗拉强度值与模型预测值的相对误差在5%以内. 结果表明,文中研究可以有效的预测与优化厚度为1.7 mm的双相钢激光焊接质量.     

Development of autocompleting friction welding method

Abstract

This paper describes an autocompleting friction welding method that was carried out to weld with an insert piece set between fixed base metals. The base metal was low carbon steel, and the faying surface of the fixed specimen had a 10 mm diameter. The effect of the thickness of the insert piece (insert thickness) on the joining phenomena was investigated. When the insert thickness was 3˙2 mm and the friction welding conditions were a friction speed of 27˙5 s^–1 and friction pressure of 36 MPa, the insert piece had a shear fracture toward the circumferential direction in the peripheral portion of the weld interfaces by the initial peak produced during the friction process. The joint also had cracks at the adjacent region of the weld interfaces, although it had the same tensile strength as the base metal. On the other hand, the joint made using the insert piece with a groove on its peripheral portion had the same tensile strength as the base metal, where it fractured. This joint also had 90° bend ductility without cracks. In this case, the optimum insert thickness was 4˙0 mm, and the thickness at the bottom of the grooves (groove bottom thickness) was 1˙2 mm with an 11 mm inner groove diameter, and the friction welding conditions were a friction speed of 27˙5 s^–1 and friction pressure of 36 MPa. In conclusion, a sound friction welded joint was made by an autocompleting friction welding method.     

1Cr18Ni9Ti+Q235复合钢板对接焊缝组织和抗腐蚀性能分析

针对内复合不锈钢焊管制造,采用4种焊接工艺对厚度为3mm+10mm的1Cr18Ni9Ti+Q235复合钢板对接焊缝进行了自动焊接,对焊接接头进行显微组织分析、拉伸、内外弯曲、冲击试验、电化学和晶间腐蚀试验.结果表明,采用TIG焊焊接复层,复层焊缝显微组织为奥氏体加少量铁素体,在1moL/L的盐酸溶液中进行电化学腐蚀试验,其抗电化学腐蚀性能与母材复层相近,无晶间腐蚀现象.基体采用TIG焊的焊接接头,基体焊缝组织为较高强韧性的板条状马氏体,满足力学性能要求.而基体采用SAW焊的焊接接头,基体焊缝力学性能和复层焊缝抗腐蚀性能均不能满足要求.     

Ni/Si中间层对铝/钢激光焊接头组织与性能的影响

研究了以Ni箔以及预置Si粉的Ni箔为中间层的铝/钢异种金属激光焊行为. 系统考察了不同激光功率下预置Si粉的Ni箔中间层对铝/钢异种金属激光焊接头组织与性能的影响. 结果表明,加入预置Si粉的Ni箔做复合中间层时,与只添加Ni箔片做中间层时相比,焊接接头的最大剪切力明显提高,其中激光功率为2 150 W时焊接接头的最大剪切力提高至1 307.96 N;Si粉的添加增加了熔池的流动性,并使得铝/钢界面的物相组成、元素分布和微观组织形态发生了改变;焊缝区生成了Fe-Si及Al-Si二元新相,有效抑制了Fe-Al二元脆性相的生成,改善了铝/钢的焊接性. 因此,预置Si粉的Ni箔复合中间层的加入,可以有效地改善铝/钢异种金属激光焊过程中的冶金反应,进而提高焊接接头的力学性能.     

镁合金激光氩弧复合热源冷填丝焊接工艺

研究了镁合金的低功率激光-氩弧复合热源冷填丝焊接工艺.通过5 mm厚镁合金板材的堆焊试验,研究了焊接电流、焊接速度、钨极高度和热源距离等参数对焊缝成形和焊接熔深的影响,确定了钨极高度为0.75 mm,热源间距DLA为1.2 mm左右的焊接参数范围;在堆焊基础上,进行了2.5 mm厚镁合金板材的对焊试验,实现了单面焊双面成形,焊接速度达1 200 mm/min,焊接接头熔深为单TIG冷填丝接头熔深的两倍,抗拉强度达到母材的95%左右,实现了高速、优质的镁合金冷填丝焊接.另外,简要分析了激光的加入对焊接过程的影响.     

高强铝合金的MIG以及激光-MIG焊接工艺对比

以20 mm厚的2519-T87高强铝合金为研究对象,研究了熔化极惰性气体保护焊 (MIG焊)和CO2激光-MIG复合焊的焊接效率、组织以及力学性能之间的区别.结果表明,激光-MIG复合焊的焊接效率是MIG焊的5倍,焊接熔深更大,接头的抗拉强度也提高到母材的70%以上,而MIG焊接头抗拉强度仅仅只有母材的60%左右.由于复合焊的热输入比较小,而且熔池的熔融金属的流动情况以及温度梯度与MIG焊有很大的不同,复合焊的焊缝组织比MIG焊的更加细小,接头处的也没有发现MIG焊接头中出现的等轴晶区.