Microstructure,residual stresses and mechanical properties of diffusion bonded tungsten–steel joint using a V/Cu composite barrier interlayer

Diffusion bonding is a preferred method to join W and steel for divertor applications. To minimize the residual stress induced by the large mismatch of thermal expansion coefficients and to inhibit the formation of brittle intermetallic phases, a V/Cu composite barrier interlayer was designed and examined to produce a joint between W and steel. The diffusion bonding was carried out at 1050 °C for 1 h under a 10 MPa pressure in vacuum. Metallographic analysis revealed excellent bonding at all of the joining interfaces. Neither intermetallic compounds nor other brittle phases were found in the bonded region. Nano-indentation test across the joint interfaces demonstrated the effect of solid solution strengthening in the diffusion zone. The strength of the joint was as high as 402 MPa and the failure occurred predominantly at the W substrate near the W/V interface due to the residual stress concentration.     

Laser transmission joint between PET and titanium for biomedical application

Laser transmission joint between biocompatible, dissimilar materials have the potential for application in biomedical and their encapsulation process. This process may involve photochemical reaction, and alter the chemical compositions of the interface and chemical bonds form at the interface. Understanding the laser joint at material interfaces is essential for the advancement in the laser joining application. This paper is devoted to laser transmission joint between 0.1 mm thick PET films and 0.1 mm thick Titanium. We have found processing conditions for successful joining of titanium with PET using near-infrared diode lasers. Laser joint samples were tested in microtester under tensile loading to determine joint strengths. The joint strength was found to be 65.46–90 MPa. The PET/titanium interfaces thus obtained were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and microscopy techniques. The results give evidence for the formation of Ti–C chemical bonds in a sharp interfacial region between the two sides. These chemical bonds are believed to be responsible for the observed mechanical strength of the joints.     

TLP bonding of Ti-6Al-4V and Mg-AZ31 alloys using pure Ni electro-deposited coats

Transient liquid phase (TLP) bonding of Mg-AZ31 and Ti-6Al-4V alloys was performed using pure thin Ni electro-deposited coat interlayer (12 μm). The effect of bonding temperature, time and pressure on microstructural developments and subsequent mechanical properties across joint interface was studied at a temperature range from 500 to 540 °C, bonding time from 1 to 60 min and bonding pressure from 0 to 0.8 MPa. The mechanisms of bond formation varied across the joint region, with solid-state diffusion dominant at the Ti-6Al-4V interface and eutectic diffusion at the Mg-AZ31 interface. Joint microstructure was examined by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) was used to detect the formation of intermetallic phases at the fracture surface. The maximum joint shear strength of 61 MPa was obtained at a temperature of 520 °C, 20 min and at a bonding pressure of 0.2 MPa. This joint strength was three times the bond strength reported for joints made using adhesives and represents 50% of the Mg-AZ31 alloy shear strength.     

镍作中间层脉冲加压扩散连接钛合金与不锈钢

采用纳米Ni粉、纳米Ni镀层、Ni箔作中间过渡层,对TA17近。型钛合金与0Cr18Ni9Ti不锈钢进行了脉冲加压扩散连接,接头抗拉强度分别达到了175,212,334MPa。在金相显微镜下,对拉伸断口形貌进行了观察和分析;利用扫描电镜（SEM）、能谱仪（EDS）、X射线衍射分析（XRD）测定了连接接头各区域内的微区成分和物相。结果表明,纳米Ni粉致密度不够高,纳米Ni镀层质量不够高,在很大程度上限制了接头强度的提高;Ni箔中间层的存在成功地阻止了Fe与Ti之间的互扩散,避免了形成脆而硬的Fe—Ti系金属间化合物。     

V/Nb复合中间层热等静压扩散连接钢/钨接头的组织与性能

采用V/Nb复合中间层成功实现了钢/钨热等静压扩散连接,并对高温低压(1 050 ℃, 20 MPa)和低温高压(950 ℃, 100 MPa)条件下形成的接头界面结构及连接强度进行了探究. 结果表明,高温低压组和低温高压组接头均呈W/Nb/V/钢四层结构,抗剪强度分别为96.9 MPa和104.2 MPa,断裂位置均为无明显化学反应发生在Nb/V界面. 与高温低压组相比,降低连接温度并提高连接压强在一定程度上有助于形成高致密度的连接接头,但不能促进薄弱界面(Nb/V)的元素扩散并显著提高接头的连接强度.     

Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder

In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.     

Diffusion Bonding of Stainless Steel to Copper with Tin Bronze and Gold Interlayers

Vacuum diffusion bonding of stainless steel to copper was carried out at a temperature ranging from 830 to 950 °C under an axial pressure of 3 MPa for 60 min with three kinds of interlayer metals: tin-bronze (TB) foil, Au foil, and TB-Au composite interlayer. The results showed that the grain boundary wetting was formed within the steel adjacent to the interface due to the contact melting between TB and Au when TB-Au composite interlayer was used. The grain boundary wetting could occur at a relatively low temperature of 830 °C and becomes significant with the increase of temperature. The tensile strength of the joint with TB-Au was higher than that with TB or Au interlayer separately and could be 228 MPa at the joining temperature of 850 °C. Furthermore, the axial compression ratio of the specimen joined at 850 °C was approximately 1.2%. Therefore, a reliable and precise joining of stainless steel to copper could be realized by diffusion bonding with the TB-Au composite interlayer at a comparatively low temperature.     

焊接温度对Mg/Al扩散焊接头微观组织和性能的影响

采用真空扩散焊在不同焊接温度下对AZ31B镁合金和6061铝合金进行连接。利用光学显微镜（OM）、扫描电镜（SEM）和能谱（EDX）观察Mg/Al异种金属接头的显微组织。结果表明：随着焊接温度的升高,扩散区各层的厚度增加,且组织发生明显变化。440°C时扩散层由Mg2Al3层和Mg17Al12层组成;460和480°C时由Mg2Al3层、Mg17Al12层和Mg17Al12与镁基固溶体的共晶层组成。随着加热温度的升高,高硬度区域显著增多,区域内不同位置的硬度存在明显差别。当焊接温度为440°C时接头的最大抗拉强度为37MPa,脆性断裂发生在Mg17Al12层。     

Microstructure and mechanical properties of diffusion bonded joints between tungsten and F82H steel using a titanium interlayer

Diffusion bonding between W and ferritic/martensitic steel F82H using a Ti interlayer was carried out in vacuum at temperature range of 850–950 °C for 1 h with 10 MPa. Metallographic analysis with field-emission scanning electron microscopy revealed excellent bonding at both W/Ti and Ti/F82H interfaces. The chemical compositions of the reaction products were analyzed by energy dispersive spectroscopy and their existence were confirmed by X-ray diffraction technique. α–β Ti solid solution was detected at W/Ti interface, while the reaction phases at Ti/F82H interface are dependent on the joining temperature. Joint strength was evaluated and the variations in strength of the joints were significantly related to the microstructural evolution of the diffusion zone. All the joints fractured at Ti/F82H interface during shear testing. The hardness distribution across the joining interfaces was also determined.     

Direct glass-to-metal joining by simultaneous anodic bonding and soldering with activated liquid tin solder

Anodically bonded glass/titanium and glass/steel were investigated for applications in a variety of industrial sectors. Residual stresses that build up during the bonding or cooling down of a joint to room temperature represent the main challenge to the joining process since they drastically weaken the mechanical strength of the joint. A layer of liquid tin-based solder in between the glass and metal part of the joint is used to reduce the internal stresses and improve the contact between the surfaces. The microstructural characterization of glass/solder/titanium and glass/solder/steel joints formed from Ni coated metal substrates indicated that Ni₃Sn₄ was formed for both types of joint but with a different morphology and location depending on the type of metal substrate. The average shear strength of the joints was 24 MPa for glass–titanium and 21 MPa for glass–steel joints. For both types of joint, the fracture crack propagated along the glass–solder interface.     

Self-pierce riveting of multiple steel and aluminium alloy sheets

Multiple steel and aluminium alloy sheets were joined by self-pierce riveting. Self-pierce riveting is attractive for joining multiple and dissimilar sheets, because joining of individual interfaces is not necessary unlike the conventional joining processes, i.e. sheets except for a lower sheet are merely pieced with a rivet shirt. The steel sheets ranged from mild steel to ultra-high strength one having 980 MPa in tensile strength, and the joinability for three steel and aluminium alloy sheets for various combinations was examined from both experiments and finite element simulation. The joinability was improved by setting a softer sheet uppermost due to smooth piercing. In addition, the joining range for self-piece riveting of three high strength steel and aluminium alloy sheets was extended by optimising a shape of the die, and the ultra-high strength steel, mild steel and aluminium alloy sheets were successfully joined.     

低活化钢双壁管的热等静压扩散连接

双壁管可控制裂纹扩展路径,防止裂纹沿管径向扩展,显著提高了管的使用安全性,被认为是聚变堆包层增殖区冷却管的理想选择.针对双壁管复合焊接难题,从钢/铜/钢和钢/镍/钢平板复合结构开展了工艺优化试验.?结果表明,热等静压温度高于1100?℃时,钢/铜/钢复合界面处发生晶界扩散,焊接接头室温抗拉强度达601?MPa,界面纳米...     

Solid state diffusion bonding of titanium to steel using a copper base alloy as interlayer

Dissimilar titanium/steel metals were successfully joined by diffusion bonding process with the help of a copper-based interlayer. The appropriate processing parameters have been investigated and the joints were analyzed by means of scanning electron microscopy (SEM), microhardness measurement, shear strength test, and X-ray diffractometry (XRD). The results show that the joint could not be bonded at a temperature lower than 800 °C even at holding time of 180 min. However, at 850 °C successful joining was achieved at all holding times. On the other hand, atom diffusion and migration between Ti and Fe or C were effectively prevented by adding a copper-based interlayer and hence, Fe–Ti and Ti–C intermetallics were not formed in the joint. This technique provides a reliable method of bonding titanium to steel.     

钨铜/铍青铜异质钎焊界面组织与性能

采用BAg56CuZnSn,BAg50ZnCdCuNi和BAg49ZnCuMnNi银钎料实施了钨铜合金/铍青铜异质材料接头的感应钎焊连接,研究了其钎焊界面组织与力学性能.结果表明,3种银钎料均能获得完好界面钎焊接头,钎料与钨铜和铍青铜形成较好冶金结合.钎料与铍青铜界面冶金结合充分,形成明显互扩散区.钎料与钨铜钎焊界面清晰,且钎料向钨铜近界面区域形成明显扩散渗入现象.强度测试表明,BAg49ZnCuMnNi钎焊接头强度最高,达到250 MPa,接头断裂均发生在钨铜侧钎焊界面.分析表明,钎料向钨铜渗入明显促进界面结合,钎料中添加镍,由于镍与钨的扩散互溶进一步提高界面冶金结合,Mn元素添加明显细化钎缝晶粒,接头强度显著提升.     

Cu/W-Ni/Ni多中间层的钨/钢扩散连接(英文)

采用铜箔/90W-10Ni(质量分数)混合粉末/镍箔多中间层,在加压5 MPa、连接温度1150°C、保温60 min的工艺条件下,对纯钨(W)和0Cr13Al铁素体不锈钢进行真空扩散连接。利用SEM、EDS、电子万能试验机及水淬热震实验等手段研究接头的微观组织、成分分布、断口特征、力学性能及抗热震性能。结果表明,连接接头由钨母材/Cu-Ni合金层/W-Ni复合材料层/镍层/钢母材五部分组成。接头中的W-Ni复合材料层由90W-10Ni混合粉末固相烧结而生成,其组织均匀、致密。W-Ni复合材料层与钨母材以瞬间液相扩散连接机制来实现良好结合。接头剪切强度达到256 MPa,断裂均发生在W-Ni复合材料层与镍层的结合区域,断口形貌呈现为韧性断裂。经过60次700°C至室温的水淬热震测试,接头无裂纹出现。     

Seal spot welding of steel and aluminium alloy by resistance spot welding: dissimilar metal joining of steel and aluminium alloy by Zn insertion

This research concerns a dissimilar metal joining of steel and aluminium (Al) alloys by means of zinc (Zn) insertion. The authors propose a joining concept for achieving strong bonded joints between Zn-coated steel and Al alloys. A eutectic reaction between Zn in the Zn coating and uniform Al–Fe intermetallic compound (IMC) layer at the joint interface, leading to a strong bonded joint. The ultimate aim of this research was to apply this joining concept in the resistance spot welding process for manufacturing vehicle bodies. As a practical issue characteristic to joints of dissimilar metals, anticorrosion measures against electrochemical corrosion must be undertaken. If there is moisture near a joint interface of dissimilar metals, electrochemical erosion will progress. Therefore, a sealing function that could prevent moisture intrusion is required. By applying the above-mentioned welding process to a set of metals with thermosetting resin spread in between, we realized seal spot welding, which not only prevented moisture intrusion but also retained high tensile strength. In this research, first, a cyclic corrosion test was performed on the seal spot-welded joint of galvanized (GI) steel, a steel grade widely distributed in Japan, and Al alloy was bonded by seal spot welding, and the following topics are discussed. Complete removal of sealant from the joint interface is the key to realizing the high tensile stress joint, because remaining sealant will lead to reduction in tensile strength. Therefore, heat generation at the interface was monitored by measuring electrical current and potential difference between the two electrodes, and a precise temperature control was performed. Moreover, the bonding process was clarified by stepwise analysis of the joint interface using optical microscopy, and a guideline for producing strong joints was proposed. And finally, a TEM observation also confirmed that the interface structure of the seal spot-welded joint was the same as joints without the resin; a thin and uniform Al–Fe IMC layer was formed and a strong metallurgical bonding was achieved.     

Effect of solidification mechanism on microstructure and mechanical properties of joint in TLP bonded Al2024‐T6 alloy

Abstract

Transient liquid phase (TLP) bonding of Al2024‐T6 alloy, using gallium (Ga) interlayer, has been investigated. Bonding process was carried out at 470°C for 6?min, and homogenising temperature and time were 495°C and 2?h respectively. Conventional TLP bonding using Ga interlayer was not an appropriate method for joining of Al2024. In this method, the boundary between two Al2024 specimens was not fully eliminated during bonding because of solidification with planar front. In addition, bonding zone was depleted of copper, and as a result, tensile and shear strength of joint decreased to 200 and 110?MPa respectively. TLP bonding under temperature gradient offered very good results in bonding of Al2024. In this method, solidification mechanism change from planar to dendritic, and tensile and shear strength of joint increased to about 460 and 220?MPa respectively. Microstructure of bonding zone changed basically by changing solidification mechanism.     

焊丝对工业纯铜和304不锈钢钨极氩弧焊接的影响(英文)

采用不同焊丝对工业纯铜和304不锈钢进行钨极氩弧焊接。结果表明,采用铜做焊丝时,焊缝无任何缺陷生成,而采用304不锈钢和Ni-Cu-Fe合金为焊丝材料时,焊缝中有凝固裂纹和未熔化区存在。在最优条件下,焊缝的抗拉强度能达到铜材的96%。焊缝在弯曲到180°下也没有分离、撕裂和断裂等现象发生。这表明铜是一种较好的工业纯铜与304不锈钢GTA焊的焊丝材料。     

Cu/W-Ni-Co/Ni多中间层的钨/钢扩散连接

采用铜箔/90W-5Ni-5Co(质量分数,%)混合粉末/镍箔复合中间层,在加压5 MPa、连接温度1120℃、保温60 min的工艺条件下,对纯钨(W)和0Cr13Al钢进行了连接。利用SEM、EDS、电子万能试验机及水淬热震实验等手段研究了接头的微观组织、成分分布、断口特征、力学性能及抗热震性能。结果表明,连接接头由钨母材、Cu-Ni-Co合金层、钨基高密度合金层、镍层、钢母材5部分组成。接头中的钨基高密度合金层由90W-5Ni-5Co混合粉末固相烧结生成,其Ni-Co粘结相和钨颗粒相冶金结合且分布均匀。钨基高密度合金层与钨母材以瞬间液相扩散连接机制实现了良好结合。接头剪切强度达到286 MPa,断裂均发生在钨基高密度合金层/镍层结合区域,断口形貌呈现为韧性断裂。经过60次700℃至室温的水淬热震测试,接头无裂纹出现。     

Microstructure－properties relationship of transient liquid phase diffusion bonded a third generation single crystal superalloy joint

Microstructure of transient liquid phase( TLP) diffusion bonded a third generation single crystal superalloy joint was investigated using scanning electron microscopy( SEM),and mechanical properties test of joint was carried out,for obtaining relationship between microstructure and mechanical properties of joint. The results showed that the joint contained bonding zone and base metal. The diffusion zone was obviously observed. When it was not finished for isothermal solidification process,the bonding zone would contain isothermal solidification zone and rapid solidification zone. Metallographic examination revealed that isothermal solidification zone was consisted of γ and γ' phase. Rapid solidification zone was consisted of two different structures,which were ternary eutectic of borides,γ and γ' phase developing at the edge of joint,binary eutectic of γ and γ' phase appearing in the portion of joint. When it was not enough for homogenization process under the condition of finishing isothermal solidification process,the bonding zone would contain isothermal solidification zone and borides at the interface. Under the conditions of relatively high welding temperature and long welding time,average tensile strength of joint was equivalent to that of parent material.