电子束焊接QCr0.8/TC4焊缝反应层结构及成长分析

QCr0.8/TC4偏铜电子束焊接焊缝由熔合区及反应层组成,其中反应层的组织结构、相组成和反应程度是影响接头抗拉强度的主要因素.参考扩散理论,利用Fick第一定律计算了稳态扩散时Cu,Ti两种组元在界面处的扩散通量比.反应层中优先生成CuTi化合物,其在反应层中为连续生成及分布.通过能谱分析得出反应层的组成依次为Cu CuxTi区,CuTi基固溶体区.其中CuxTi为多种化合物的混合,如Cu4Ti,Cu3Ti,Cu2Ti等.由于电子束焊接接头冷却速度极快,TC4侧靠近熔合线处来不及生成第二相化合物,因此反应层处形成的连续金属间化合物CuTi层使该处变得硬脆且残余应力较大,成为影响接头力学性能的主要因素.     

QCr0.8/TC4薄板电子束焊接头组织及断裂路径

对QCr0.8/TC4异种材料薄板进行了电子束对接焊接试验.采用光学金相、扫描电镜、能谱分析及X射线衍射相分析等方法,对接头组织结构及相组成进行了分析.并对接头进行了性能测试及断口形貌观察,分析了断裂性质,探讨了断裂路径.结果表明,焊缝由大量的γ-CuTi相、金属间化合物CuTi2,CuTi3及少量的铜基固溶体组成,且靠近铜合金侧存在一层20 μm左右的反应层,推测其可能为Ti2Cu,CuTi,Cu4Ti3,Cu2Ti,Cu3Ti等多种金属间化合物混合层;QCr0.8/TC4的电子束对中焊接性较差,接头断裂发生在焊缝中心的粗晶区,呈明显的解理断裂特征,接头抗拉强度很低,仅为82.1 MPa.     

Ti6Al4V/Cu异种金属激光焊接头组织及性能研究

为解决Ti/Cu异种金属焊接时形成TixCuy脆性相严重降低接头力学性能的问题,利用激光诱导钎焊反应方法对采用Nb做中间层的Ti6Al4V和Cu材料进行了焊接。将光束置于Ti6Al4V/Nb界面控制热输入使得Nb中间层部分熔化形成焊接接头。结果表明,在Ti6Al4V/Nb界面形成了由(Nb,Ti)固溶体组成的熔化区,依靠未熔化的Nb从熔化区吸取的热量使得Cu熔化从而润湿Nb,在Nb/Cu界面形成了Cu基和Nb基固溶体组成的钎焊连接层。因此,通过一次焊接形成了两个连接界面。Ti6Al4V和Nb被熔化焊连接,而Nb和Cu被钎焊连接,两个区域被未熔化的Nb隔开,从而抑制了Ti_xCu_y金属间化合物的形成。接头的抗拉强度达到225 MPa,并且呈典型的韧性断裂模式。     

采用不同结构Cu/V填充层的钛合金/不锈钢电子束焊接试验

对采用不同结构Cu/V填充层的钛合金与不锈钢电子束焊接头横截面形貌、微观组织及力学性能进行了分析.结果表明,采用片层结构的Cu/V填充层进行焊接时,焊缝组织由钒基固溶体、铜基固溶体及铁基固溶体组成,但由于焊缝底部有钢层未熔,形成未熔合缺陷,接头强度为288 MPa.采用楔形结构的Cu/V填充层,在保持接头固溶体过渡组织结构特征的同时,消除了未熔合缺陷,接头抗拉强度达到385 MPa.未熔钒层为接头力学性能薄弱区域,不同结构填充层的焊接接头断裂均发生于未熔钒层处.     

复合阻隔镀层对钒合金与不锈钢电子束焊接头组织与性能的影响

钒基合金被公认为是理想的聚变反应堆结构材料,为了更有效和经济地利用钒基合金,需要将钒合金与不锈钢进行连接。通过电镀Ni+Au作为复合中间层,采用电子束阻隔熔化焊方法来实现V-5Cr-5Ti钒合金与HR-2不锈钢之间的连接。结果表明:电子束流偏向钒合金一侧焊接得到的钒合金与不锈钢接头界面将产生贯穿性裂纹,直接导致焊接失败。电子束流偏向不锈钢一侧,电镀Ni+Au作为界面阻隔层,很好地抑制了V/Fe界面的金属间化合物的产生,显著提高了接头性能,接头抗拉强度最高达到430 MPa。电子束阻隔熔化焊得到的钒合金/不锈钢异种金属焊接接头焊缝正反面成形良好,X射线探伤未发现裂纹和气孔缺陷。     

V5Cr5Ti与HR-2电子束熔焊接头微观结构与力学性能研究

采用OM、XRD、TEM等分析手段和力学测试方法,研究了钒合金(V5Cr5Ti)与HR-2电子束焊接接头的微观结构与力学性能。研究表明：电子束焦点偏移结合斜I型对接坡口,控制焊缝V5Cr5Ti体积熔合比小于15%可实现V5Cr5Ti与HR-2异种材料无缺陷熔焊连接,接头抗拉强度约400Mpa,断口呈现典型的混合型特征。V5Cr5Ti/HR-2接头焊缝边缘相结构取决于其区域V原子的富集程度,富集程度低,生成Fe-Cr体心立方固溶体,V原子以置换晶格中Fe原子形式存在；富集程度高,则形成Fe_0.1Ti_0.18V_0.72、V₂Cr₂Fe金属间化合物。焊缝中心区域相结构与熔合比无关,皆生成Fe-Cr体心立方固溶体；V5Cr5Ti/HR-2焊缝热、冷裂纹影响因素一是因焊缝生成富钒金属间化合物,二是接头在整个焊接热循环期间将承受较大焊接热应力及其随后的残余应力。     

中间层厚度对TLP扩散连接TC4组织和性能的影响

采用电沉积Ni/Cu层作为中间层实现了TC4钛合金瞬时液相（TLP）扩散连接,采用扫描电子显微镜、能谱仪和X射线衍射仪研究了Cu层厚度对TC4钛合金接头界面微观组织和力学性能的影响,并结合Ti-Cu和Ti-Ni二元相图阐明了反应机制。结果表明,瞬时液相扩散连接接头的典型界面组织为TC4/α-Ti+Ti2(Cu, Ni)/TC4,其中Ni元素均以固溶体的形式存在于接头中。随着电沉积Cu层厚度增加,扩散层和焊缝宽度增加,接头中央未焊合的孔洞消失,反应层中开始出现连续的Ti2(Cu, Ni)金属间化合物层且宽度逐渐增加。接头抗拉强度在电沉积Cu层厚度为15 μm时达到最大值500 MPa。断裂分析表明,所有TLP扩散连接接头均以解理断裂方式在焊缝处断裂。     

钛合金与GCr15扩散连接界面组织特征与性能

钛合金/轴承钢异种结构连接困难是制约钛合金广泛应用的瓶颈.采用电子拉伸显微硬度测试、SEM扫描、能谱、X射线衍射等分析手段,分析研究了Ti-6Al-4V/Cu/GCr15真空扩散焊接头的力学性能、组织结构特征、连接界面的原子扩散机制、反应相生成及其分布范围.结果表明,在焊接压力4.9MPa,焊接时间1.8ks条件下,接头的抗拉强度随焊接温度升高而增大,1273K达到最大为206MPa.延长焊接时间会导致金属间化合物厚度增大,对接头性能不利.接合界面间生成的α-Ti(Cu)固溶体,有固溶强化效果,对提高接头性能有利.而生成的金属间化合物Ti2Cu,Ti2Cu3,(Ti3Cu4)FeTi中的TixCuy对接头性能影响较大,导致接头强度下降.铜作为钛合金与GCr15的中间过渡层不宜过厚.     

TC4/OFC真空扩散焊接研究

对钛合金（TC4）与无氧纯铜（OFC）异种金属在真空条件下进行直接扩散焊接,可形成良好的TC4/ OFC焊接接头。测量其焊接强度及进行微区分析的结果表明,随着温度升高,焊接接头的抗拉强度先升高后下降,最佳焊接工艺参数为：焊接温度800 ℃,保温时间30 min,焊接压力5 MPa。在TC4/ OFC焊接接头的界面上形成了元素成分逐渐变化的互扩散层。由元素分析和断口的XRD分析结果可以看出,界面处生成的物相有Cu3Ti2、Cu4Ti3、CuTi、Cu4Ti等金属间化合物,断口的形貌表明接头断裂主要发生在接头的金属间化合物弱结合处,结合处的孔洞与铜钛金属间化合物的种类、厚度决定了TC4/OFC直接扩散焊接接头的强度。     

TiZrNiCu钎料钎焊Ti53311S高温钛合金接头界面结构及性能

采用TiZrNiCu钎料实现了Ti53311S高温钛合金的钎焊连接,通过SEM、EDS、微区XRD等方法分析了接头界面的微观组织结构,重点研究了钎焊温度对接头界面结构及力学性能的影响规律。结果表明,钎焊接头的典型界面结构为:Ti53311S/α+β/(Ti,Zr)2(Cu,Ni)化合物/α+β/Ti53311S;随钎焊温度的升高,(Ti,Zr)2(Cu,Ni)化合物数量不断减少,当钎焊温度超过α+β→β转变温度时,钎缝及钛合金母材均形成片层状α+β组织;接头抗拉强度随钎焊温度升高逐渐增加后趋于稳定,当在1010℃/10 min条件下钎焊时,接头平均抗拉强度最大为912.8 MPa,断口分析表明,断裂发生于钎缝处,为脆性解理断裂。     

Microstructures and Mechanical Properties of Electron Beam-Welded Titanium-Steel Joints with Vanadium,Nickel, Copper and Silver Filler Metals

Electron beam welding experiments of titanium alloy to stainless steel with V, Ni, Cu and Ag filler metals were carried out. The interfacial microstructures of the joints were examined by optical microscopy, scanning electron microscopy, and x-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics formed in the Ti/Fe joint. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. And the type of solid solution and interfacial intermetallics were depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe₂Ti + Ni₃Ti + NiTi₂, TiFe, Ti₂Ag, and Cu₂Ti + CuTi + CuTi₂ in the joints welded with Ni, V, Ag, and Cu filler metals, respectively. The tensile strengths of the joints were primarily determined by the hardness of the interfacial intermetallics. The highest tensile strength was obtained in the joint welded with silver filler metal, which is about 310 MPa.     

陶瓷/AgCuTi/不锈钢钎焊连接界面组织与结构

采用Ag-Cu-Ti钎料对日用陶瓷与1Cr18Ni9Ti不锈钢进行了钎焊连接.用扫描电镜、能谱仪以及X射线衍射仪对接头的微观组织形貌、特征点的成分以及钎焊接头的物相等进行了分析研究.结果表明,接头界面处形成了多种化合物,包括TiO,TiSi_2,Ti_5Si_3和Fe_2Ti.当温度为850℃,保温时间为5 min时,接头界面结构为1Cr18Ni9Ti不锈钢/Fe_2Ti/Ag[s,s]+Cu[s,s]+Fe_2TiO+Ti_5Si_3+TiSi_2/陶瓷.当钎焊温度较高或保温时间较长时,界面反应层厚度增加,界面中基体相Ag[s,s],Cu[s,s]所占比例显著减小.

Abstract：

Domestic ceramics and lCrl8Ni9Ti stainless steel were brazed using Ag-Cu-Ti filler metal. Microstructure, the component of characteristic points and the phases of brazing joints were studied by scanning electronic microscopy ( SEM) , energy distribution spectrometer (EDS) and x-ray diffraction (XRD). The results show that several kinds of intermetallics such as TiO_2, TiO, TiSi_2 , Ti_5 Si_3 and Fe_2 Ti were formed. The interfacial structure of joints is 1Cr18Ni9Ti stainless steel/Fez Ti/Ag[ s, s] + Cu[s,s] + Fe_2Ti/TiO_2 + TiO + Ti_5Si_3 + TiSi_2/ceramics when brazing temperature and time are 850 ℃ and 5min, respectively. The depth of interfacial reactive layer increases and the ratio of matrix phase Ag [ s, s ], Cu [ s, s ] which are in the middle of interface reduces evidently as brazing temperature is very high or holding time is very long.     

TC4／Ag-Cu—Ti／1Cr18Ni9Ti钎焊接头界面组织与结构

以Ag—Cu—Ti箔状钎料对钛合金TCA和不锈钢1Cr18Ni9Ti进行了真空钎焊。采用扫描电镜、能谱分析、金相显微镜和x一射线衍射等分析测试手段对钎焊过程中所形成的反应产物和接头界面结构进行了分析。结果表明：接头界面形成了Ti（s．s）、AS（s．s）、Ti—Cu金属问化合物等反应产物。连接温度较低（920℃）时,界面结构依次为1Cr18Ni9Ti／TiCu／Ag（s．s）＋少量Ti2cu／％2cu／Ti2cu＋Ti（s．s）／TC4;连接温度升高（960oC）时,界面结构为1Crl8Ni9Ti／Ti：Cu／Ti：Cu＋矩（s．s）／Ti2Cu／Ti2Cu＋Ti（s．s）／TCA;连接温度较高（1000oC）时,界面结构为1Crl8Ni9Ti／TiCu2／TiCu／Ti2Cu／Ti：Cu＋Ti（s．s）／TC4。提高钎焊温度与延长保温时间对钎焊接头界面组织结构有相似的影响,各反应相、反应层逐渐长大,金属问化合物反应相所占比例增大,而Ag（s．s）组织所占的比例变得更小,这种趋势随着焊接工艺参数的提高更加明显。     

Welding austenitic steel to copper with the defocused radiation of a fibre laser

Special features of producing butt welded joints between 12Cr18Ni10Ti austenitic steel and M1 copper by laser welding are investigated. Welding was carried out without filler or intermediate material. The defocused beam of the fibre laser, displaced to the austenitic steel, was used. The welded joints in dissimilar materials produced in the selected conditions were without defects and their strength was comparable with the M1 copper parent metal. The tensile tests and hardness measurements were carried out on the resultant welded joints. The microstructure of the welded joints was investigated and the transition zone was examined by chemical analysis.     

Study of diffusion bonding of Ti-6Al-4V and ZQSn10-10 with metal interlayer

The diffusion bonding was carried out to join Ti alloy (Ti-6Al-4V) and tin-bronze (ZQSn10-10) with Ni and Ni Cu interlayer. The microstructures of the diffusion bonded joints were analyzed by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that when the interlayer is Ni or Ni Cu transition metals both could effectively prevent the diffusion between Ti and Cu and avoid the formation of the Cu-Ti intermetallic compounds (Cu3Ti, CuTi etc.). But the Ni-Ti intermetallic compounds (NiTi, Ni3Ti) are formed on the Ti-6Al-4V/Ni interface. When the interlayer is Ni, the optimum bonding parameters are 830℃/10 MPa/30min. And when the interlayer is Ni Cu, the optimum bonding parameters are 850℃/10MPa/20min. With the optimum bonding parameters, the tensile strength of the joints with Ni and Ni Cu interlayer both are 155.8MPa, which is 65 percent of the strength of ZQSn10-10 base metal.     

Contact Reactive Joining of TA15 and 304 Stainless Steel Via a Copper Interlayer Heated by Electron Beam with a Beam Deflection

TA15 titanium alloy and 304 stainless steel were joined via a copper interlayer heated by electron beam with a beam deflection towards the stainless steel. Microstructures of the joints were analyzed by optical microscopy, scanning electron microscopy, and X-ray diffraction. The tensile strengths of the joints and the ultramicrohardness of the intermetallic compounds were also measured. The results showed that the joint was formed by three kinds of metallurgical processes. Copper interlayer and TA15 were joined by contact reaction with the reaction products of CuTi, Cu₄Ti₃, and Cu₂Ti. While copper interlayer and 304 stainless steel were joined by fusion and solid state diffusion process. Tensile strength of the joint can reach to 300?MPa, equivalent to 55% of that of 304 stainless steel. Furthermore, the tensile strength was mostly dependent on the volume of the unmelted copper sheet, although the intermetallics layer was the weakest location in the joint.     

Si,Mg对铝/钢熔钎焊焊接接头力学性能的影响

采用脉冲旁路耦合电弧MIG熔钎焊方法,分别采用4043,5356铝合金焊丝对5052铝合金/镀锌钢异种金属进行了搭接焊.通过扫描电镜（SEM）,能谱仪（EDS）,X射线衍射仪（XRD）对铝/钢连接界面、接头断裂行为及断口形貌进行了分析,发现5356铝合金焊丝焊接接头的润湿角要大于4043铝合金焊丝焊接接头的润湿角,合金元素Si既可改变界面反应层金属间化合物的形态同时还可显著减少Fe₂Al₅层的厚度.拉伸试验发现5356铝合金焊丝焊接所得接头主要断裂于界面反应层,属于脆性断裂;4043铝合金焊丝焊接所得接头主要断裂于熔合区,是以韧性断裂为主的混合断裂.通过对4043铝合金焊丝焊接所得接头进行显微硬度测试,发现热影响区组织的显微硬度明显低于其它区域的显微硬度,这导致4043铝合金焊丝焊接接头主要断裂于熔合区.     

Influence of Vanadium Element on Microstructure of Electron Beam Welded Titanium Alloy to Stainless Steel Joint

Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were carried out.Microstructures of the joints were examined by scanning electron microscope.The properties were evaluated by microhardness and tensile strength.It was shown that electron beam welding is not feasible due to the brittle Ti-Fe intermetallics with high hardness.Increase of vanadium content in base metal can restrain but can’t avoid the formation of cracks.When vanadium content was too large,the joint was embrittled by FeTi compound with supersaturated V and also cracked after welding.Crack free joint was achieved by using vanadium transition portion which can prevent the contact of Ti and Fe elements.However,the formation of brittle σ intermetallics reduced the tensile strength of the joint,only up to 134MPa.     

Laser brazing of a dissimilar joint of austenitic stainless steel and pure copper

In many industries, there are applications that require the joining of stainless steel and copper components; therefore, the welding of dissimilar stainless steel/copper joints is a common process. For this investigation, the optimal brazing conditions and suitable filler metals for laser brazing of stainless steel/copper lap joints were studied. Tensile shear force increases with increases in the laser spot diameter or in the laser irradiation angle, which is associated with increased bonding width; however, as bonding width approaches 2 mm, tensile shear force reaches a saturated value due to fracturing at the HAZ of the Cu base plate. In order to obtain joints with high tensile shear strength, laser brazing was optimized by using Cu–Si-based filler metal under the following conditions: laser power, 4 kW; spot diameter, 3 mm; laser irradiation angle, 80°; irradiation position shift, 0.6 mm; brazing speed, 0.30 m/min; and filler metal feed speed, 0.30 min. Concerning filler metals, it was found that the Ni–Cu type showed relatively large tensile shear force even at high welding speeds in comparison with those of the Cu–Si, Cu, Cu–Ni, Ni–Cu and Ni types, respectively.