"相变-扩散钎焊(T/DB)"新工艺及其接头界面形貌

为减小相变超塑性扩散连接的循环次数,提出了一种新型焊接工艺"相变-液相扩散焊(T/DB)",即在待焊母材间预先放入液相扩散焊用的中间层,然后按传统相变超塑性扩散连接工艺施焊,但要求温度循环的峰值温度须同时大于母材的相变点与中间层的熔点.试验以低碳钢为母材,以镍基非晶箔带(BNi2)为中间层,进行了低碳钢的相变-扩散钎焊(循环3次)与液相扩散焊接(1200℃×3 min)的对比试验.结果表明相变-液相扩散焊所需温度循环次数少,接头无界面空洞,其接合线呈非平面状;而液相扩散焊接头的接合线较平直.分析认为,界面的起伏是母材的适度溶解与超塑性流变共同作用的结果;非平面状界面有利于增大金属-金属接触面积及扩散通道的面积,为获得合格接头做出了相应贡献.     

工业纯钛TA2/紫铜T2异种金属CMT焊接接头的微观组织和腐蚀性能

采用冷金属过渡技术(CMT)对工业纯钛TA2和紫铜T2异种金属薄板进行对接焊.焊接过程中,使焊丝偏向铜的一侧,铜母材和焊丝熔化形成熔焊接头,熔化的填充材料润湿钛母材,形成钎焊界面,实现钛和铜的熔钎焊连接.使用扫描电镜(SEM)、能谱分析(EDS)和力学试验研究焊接接头的组织以及连接机理.在室温下10%HCl溶液中,研究钛/铜异种金属CMT焊接接头的腐蚀行为.结果表明,钎焊界面由TiCu,Ti₂Cu,AlCu₂Ti等多种金属间化合物组成;焊缝区由铜基固溶体和Ti-Cu-Al-Ni-Fe五元素析出相组成;接头的抗拉强度达到205 MPa;焊接接头在室温10%HCl溶液中腐蚀7天后,钎焊界面出现腐蚀沟槽,14天后自行断裂.     

高效焊管新工艺——金属管液相扩散焊

采用镍基非晶态箔带作中间层,在加压情况下(约几MPa)使之熔化、保温,进行了钢管瞬间液相 (TLP)扩散焊试验。结果表明,可以获得无夹杂的致密界面;接头过渡区的最终厚度显著变薄;焊后中间层主组元由焊前的Ni变为Fe;容易获得性能合格接头。值得指出的是,焊接时间约为3min,远低于手弧焊所需时间。     

Testing of PTA automatic braze-welding technology for producing absorber joints of solar collectors

The article presents research aimed at developing a PTA braze-welding technology for producing absorber connections between tubes and copper foil with EcoBraz 38102 self-fusible brazing solder in the form of wire 1 mm in diameter. Braze-welding process was carried out by means of two techniques of braze welding of flat copper foil to a tube, while the foil had a 0–1.5 mm wide gap: a connection with a butt joint made by braze welding with simultaneous stamping of a semi-circular channel in the copper foil (the channel diameter equal to the tube diameter); and a connection with two braze-welded fillet joints. Metallographic tests, hardness measurement, static tensile test and thermal conduction efficiency test were performed to determine the properties of prepared connections. It was demonstrated that there exists a field of PTA braze-welding parameters which assures high quality of absorber connections between tubes and copper foil.     

Bonding of Al2O3 ceramic and Nb using transient liquid phase brazing

The brazing of Al2O3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni-5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1423-1573 K for 1-120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni3Ti, is formed when the brazing temperature is 1473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni-5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al2O3 results in the bonding of Al2O3 and Nb.     

Corrosion behaviors of Al-Si-Cu-based filler metals and 6061-T6 brazements

The corrosion behaviors of a series of Al-Si-Cu-based filler metals and the 6061-T6 butt joints brazed with these filler metals are evaluated by polarization tests and immersion tests in a 3.5% NaCl aqueous solution. For comparison, a traditional Al-12Si filler metal is also employed. The results indicate that the Al-Si-Cu-based filler metals before brazing possess much higher corrosion current densities and pitting tendencies than the Al-12Si filler metal. However, brazing of the 6061-T6 alloy with an Al-12Si filler metal produces a wider butt joint, which, in this case, creates a more extensive corrosion region. Severe galvanic corrosion occurs at the 6061-T6 joints when brazed with Al-Si-Cu-based filler metals. However, in the case of the 6061-T6/Al-12Si brazements, selective corrosion of the Al-12Si eutectic phase can be observed. The bonding strengths of the 6061-T6 butt joints brazed with various filler metals are also measured before and after the immersion tests.     

不锈钢与耐候钢MIG电弧钎焊工艺

采用手工MIG电弧钎焊工艺对SUS304不锈钢与Q355GNHD耐候钢薄板对接接头进行工艺试验,按照相关技术标准进行焊接工艺评定。结果表明,MIG电弧钎焊工艺能够成功用于SUS304不锈钢和Q355GNHD耐候钢薄板对接接头的钎焊,焊缝成形质量良好,经X射线探伤无缺陷;接头的抗拉强度平均值为339.58 MPa,接头强度系数为78.97%。采用光学显微镜观察SUS304不锈钢与铜基钎料间产生的渗透裂纹,讨论渗透裂纹的产生机理。     

冷热冲击对无铅钎料可靠性的影响

文中对比了一种新型低银钎料Sn-Ag-Cu-Bi-Ni（SACBN07）与市场上的SAC305,SAC0307两种无铅钎料的抗冷热冲击性能.利用纳米压痕试验等微观测试方法研究时效后界面组织及力学性能的变化.结果表明,SACBN07的抗冷热冲击性能最好,焊点失效后三种材料中裂纹的扩展路径不同,SAC305失效裂纹位于体钎料中,SACBN07钎料断裂位置逐渐由钎料基体转移到金属间化合物（IMC）层中,而SAC0307断裂位于界面IMC中;钎料中Bi,Ni元素的加入有效地抑制了IMC的生长,相同冷热冲击时间,SACBN07钎料中界面IMC厚度最薄;SACBN07体钎料的硬度受冷热冲击影响最小,时效后仅降低了8.6%,而SAC305与SAC0307分别降低了12.5%和28.3%.     

玻璃与金属真空钎焊接头残余应力影响参数分析

玻璃和金属焊接接头由于设计不合理,将致使接头存在较大的焊接残余应力,会严重削弱接头强度.应用顺次耦合有限元热应力计算方法,对平板玻璃和金属在真空条件下的钎焊过程进行了数值模拟,分析了玻璃、金属、钎料厚度、钎焊压力和钎焊温度等因素对应力集中区域残余应力的影响,并观察了焊接接头拉伸断裂后的形貌特征.结果表明,金属厚度增加会增大残余应力,并且其对残余应力影响最显著;钎焊压力和钎焊温度的增加可以降低残余应力;玻璃和钎料厚度对残余应力的影响不大;焊接接头的拉伸断裂区域位于玻璃和金属焊接接头界面贴近玻璃一侧.     

非晶态镍基钎料箔润湿成缝特征及其对钎焊接头形态的影响

通过分析控制非晶态镍基钎料箔用量的钎焊试验结果,对非晶态镍基钎料箔的润湿成缝特征及钎焊接头形态进行了研究.结果表明,即使在钎料不足的情形下,钎料残余层也始终存在,在熔融钎料同母材的相互作用下,钎料残余层/母材界面向母材一侧发生迁移;钎料残余层厚度随钎料量的增加而增大,但界面迁移深度与钎料箔大小无关.熔融钎料成缝行为遵循能量最低原理,其受自身重力、粘滞力和表面张力引起的附加压力共同作用,流动成缝时具有粘性流体的特征,贴近母材表面的边界层流速趋缓,母材向熔融钎料中的溶解则进一步降低了其流动性,最终凝固形成钎料残余层.     

用Al—Ti—Al合金钎料复合板钎焊钛的研究

介绍了用Ａｌ－Ｔｉ－Ａｌ合金金属复合板钎焊工业纯钛的研究结果。这种金属复合板是采用特殊的轧制复合工艺加工而成的。复合板的两个外表面包含一层０．１ｍｍ厚的Ａｌ合金钎料,其中间夹层是０．４ｍｍ厚的工业纯然板。在本实验中用这种复合板替代传统单一的Ａｌ合金钎料薄片来钎焊钛的蜂窝结构,其结果是简化了钎焊工艺,使焊点更加均匀。同时还研究籽焊缝的剪切强度,宏观和显微组织。并比较了用单一Ａｌ合金钎料薄片钎焊和用该     

Microstructure and Mechanical Properties of Plasma Arc Brazed AISI 304L Stainless Steel and Galvanized Steel Plates

Plasma arc brazing is used to join the AISI 304L stainless steel and galvanized steel plate butt joints with the CuSi3Mn1 filler wire. The effect of parameters on weld surface appearance, interfacial microstructure, and composition distribution in the joint was studied. The microhardness and mechanical tests were conducted to determine the mechanical properties of the welded specimens. The results indicated that good appearance, bead shape, and sufficient metallurgical bonding could be obtained when the brazing process was performed with a wire feeding speed of 0.8 m/min, plasma gas flow rate of 3.0 l/min, welding current of 100 A, and welding speed of 27 cm/min. During plasma arc brazing process, the top corner of the stainless steel and galvanized steel plate were heated and melted, and the melted quantity of stainless steel was much more than that of the galvanized steel due to the thermal conductivity coefficient difference between the dissimilar materials. The microhardness test results shows that the microhardness value gradually increased from the side of the galvanized steel to the stainless steel in the joint, and it is good for improving the mechanical properties of joint. The tensile strength was a little higher than that of the brazing filler, and the fracture position of weld joint was at the base metal of galvanized steel plate.     

Effect of Shoulder Diameter on the Force Generation,Microstructure and Mechanical Properties of Friction Stir-Brazed Aluminium Alloy and Copper with Ultrahigh Rotation Speed

Friction stir brazing with ultrahigh rotation speed was applied to 6061 aluminium alloy-pure copper lap joints with the aid of zinc foil. The effects of different shoulder diameters from 7 to 15 mm on the microstructure and mechanical properties of Al/Cu FSB joints were investigated along with the temperature and resistance of the friction tool. The oscillation of forward resistance and lateral force was related to the flow of the plastic metal and contributed to obtain a good appearance during the welding process. From the appearance of the welded joints, it was obvious that the phase difference between the forward resistance and lateral force had a significant influence on the joint characteristics. Obvious scale-like ripples appeared on the weld area when a sharp angle in the phase difference curve existed. Additionally, with a lower axial force and oscillation assistance, a satisfactory joint could be obtained. The results of the shear strength of the brazed joint showed that the shoulder with a 12 mm diameter yielded the highest shear strength. Meanwhile, the zinc foil in the middle melted completely and formed finely dispersed CuZn₅ Al-Zn eutectic structures at the Al-Cu interface.     

Brazing of Coated Al Foil Filler to AIN CeramicEI北大核心CSCD

The wettabilities of molten metals on ceramics are poor normally. In order to improve the wettability, all existing ceramic brazing methods introduce a compound transition layer formed by the reaction of active metal and ceramic. The transition layer between brazing seam and ceramic however creates negative effect on the properties of brazing joints. Although Al is the scarce metal which can wet some ceramics such as AIN and Al2O without reaction, the difficulty of removing oxide layer on surface prevents it being ceramic brazing filler. This work proposed a kind of coated Al foil filler able to remove its own Al2O3 film and an elevating temperature brazing process to enhance Al/AIN joint strength. Removing Al2O3. film effect of vapor deposited Ni/Al double layer film on Al foil and the effect of brazing temperature on improving joint strength were studied. The results showed that due to buried by Ni/Al double layer film, Al2O3 film on Al foil original surface broken and was swept in Al-1%Ni (atomic fraction) alloy liquid during heating and melting process. As a result, the direct brazing of Al to AIN without interface reaction transition layer was realized. The joint strength was significantly enhanced by elevating brazing temperature. When brazing at 680 degrees C, the joint fractured along the interface between Al seam and AIN and the sheer strength was 79 MPa because of Al liquid not wetting AIN. With the elevating of brazing temperature, the wettability and interface strength of Al/AIN improved. The fracture gradually transferred to brazing seam from interface. The joint strength increased and reached to the maximum value of 146 MPa at 840 degrees C.     

铝合金三元气体保护焊温度场及接头组织特征

针对铝合金三元气体保护焊力学性能提升原因分析的需求,使用测温系统采集铝合金纯氩气体保护、三元气体保护焊接的热循环曲线,分析焊接温度场特征的差异. 研究发现三元气体保护焊温度场更加集中,峰值温度更高,降温速率更快. 对纯氩气体保护、三元气体保护焊接头进行染色法观察发现,三元气体保护堆焊时晶粒更大,气孔率更低;对接焊时,三元气体保护焊接头的半熔化区存在晶界液化现象,三元气体保护焊的晶界液化现象更加严重,半熔化区宽度更窄. 结果表明,焊接温度场是引起焊接接头力学性能提升的根本原因.     

细直径TA2/0Cr18Ni9Ti棒材储能焊接试验分析

采用电容储能焊机对直径2.5 mm的TA2纯钛和0Cr18Ni9Ti不锈钢异种棒材进行快速凝固对接研究,分析了接头显微组织和界面结合机制,测试了接头力学性能.结果表明,储能焊能够实现TA2与0Cr18Ni9Ti之间的快速凝固焊接,获得的焊接接头组织细小致密,极快的焊接速度有效抑制了接头中TiFe2,TiFe等脆性金属间化合物的生成.接头缺陷主要为裂纹,并具有脆性断裂特征,裂纹多发于0Cr18Ni9Ti侧,穿过熔合界面向熔核延伸.当焊接电压为195 V,电容为9 900μF,电极力为15 N时,接头抗拉强度达到480 MPa.     

Cu-P基非晶钎料钎焊机理

采用CuP7．7Sn5．4Nil4Si0．2Zr0．04晶态与非晶钎料钎焊紫铜,通过微观手段对比分析了钎焊温度和保温时间对晶态与非晶态钎料钎焊接头成分和组织的影响．结果表明,CuP7．7Sn5．4Nil4Si0．2Zr0．04非晶钎料钎焊接头由界面区、扩散区以及钎缝中心区组成;随钎焊温度提高或保温时间增加,晶态钎料和非...     

TiNi形状记忆合金电阻钎焊接头微观组织分析

利用自行改制的数控交流电阻焊机，采用CuNi薄带钎料，配合改进型钎剂实现了TiNi形状记忆合金电阻钎焊连接。借助于光学显微镜、SEM及EDX对钎缝的组织进行了分析。结果表明，试验采用的电阻钎焊工艺对母材的热影响极小，接头中没有明显的热影响区；在钎缝中存在的Ti，Ni4化合物相是TiNi合金产生双程及全程形状记忆效应的主要因素。     

铝铜异种金属冷压焊及其焊缝接头显微组织和性能

研究了铝铜异种金属冷压焊的焊接工艺,对铝和铜的焊接性能及冷压焊的焊接特点进行了分析.用冷压焊进行了铝铜异种金属对接接头的焊接试验,并对冷压焊的焊接工艺参数的选择进行了试验和分析.对焊接接头的显微组织、抗拉强度、抗弯强度、电阻性能、耐温度变化性能及接头耐高温性能进行了试验和分析,其结果为铝铜异种金属焊接在电气产品中的使用提供了依据.     

TC4钛合金蜂窝板钎焊接头组织性能分析

研究了TC4钛合金蜂窝板的钎焊工艺,试验采用Ti-Zr-Ni-Cu钎料,真空度不低于2×10-3 Pa,钎焊温度为930℃,保温时间为30 min.对焊后试件的钎焊界面组织进行超声无损检测,检测结果表明面板与蜂窝芯钎焊效果极好,未发现有脱焊、虚焊等现象.采用扫描电镜（SEM）和能谱分析（EDS）法进行了试验分析.结果表明,母材和钎料发生相互扩散渗透反应,并出现有新的析出相.该工艺下蜂窝板的界面平均拉脱强度为12.8 MPa,抗剪强度为9.01 MPa,钎焊接头属于脆性断裂.