铝锂合金钎焊接头断口组织与性能

采用金相显微镜、扫描电镜、硬度计等测量方法,观察分析了铝锂合金钎焊前后母材和钎焊接头的显微组织变化,通过分析测试钎焊接头的显微硬度和断口微区的化学成分,研究分析了钎焊接头强度的变化规律.结果表明,焊后母材中的强化相由质点转变为板条状;氮气保护条件下,钎焊接头未见气孔、夹杂、裂纹等缺陷,钎焊接头存在一定的扩散区,从而有效地提高了钎焊接头的强度;无氮气保护的条件下,钎焊接头有大量的缺陷存在,这些缺陷的存在严重影响了钎焊接头的强度.     

Ultrasonic guided wave inspection of Inconel 625 brazed lap joints: Simulation and experimentation

The aerospace industry has been investigating the use of structural brazed joints. As a result of this effort, there is now a need for a rapid, robust, and cost-effective non-destructive testing method to evaluate the structural integrity of the joints. The mechanical strength of brazed joints is known to depend on the microstructural quantity of brittle phases. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the quantity of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint. Experimental validations were then performed on three distinctive samples with variable amount of brittle phases in the joint. The samples had three different brazing times (1, 60 and 180 min). Finally, experimental results were in accordance with simulations and demonstrate the potential of the inspection method to estimate the quantity of brittle phases in a lap joint.     

化学镀锡钎料钎焊黄铜的接头组织和力学性能

采用化学镀方法在BAg45CuZn钎料表面镀覆微米锡层,并用镀锡银钎料以火焰钎焊工艺连接H62黄铜。借助金相显微镜、扫描电镜(SEM)和X射线衍射仪(XRD)分别分析锡化学镀层、H62黄铜钎焊接头的显微组织和物相,并利用万能拉伸机和SEM表征钎焊接头的抗拉强度和断口形貌。结果表明,锡化学镀层结晶晶粒呈现明显的(110)、(210)择优取向,化学镀锡银钎料连接的接头中母材与钎缝结合紧密,接头组织中富Cu相减少,出现Cu_5Zn_8化合物相。随着基体钎料表面镀锡含量升高,钎焊接头的抗拉强度呈现先升高后降低趋势。在化学镀锡含量为6.0%(质量分数)时,钎焊接头的抗拉强度为353MPa。镀锡前后钎焊接头的拉伸断口均呈现韧性断裂。     

Fatigue Assessment of Defect-Free and Defect-Containing Brazed Steel Joints

This work aims at the development of lifetime estimation procedures for defect-free and defect-containing brazed joints. Preliminary investigations were performed to measure the influence of specimen geometry on the joint strength. To estimate the influence of defects on the fatigue lifetime, defect-free specimens were compared with specimens containing defects. The experiments show that defect-containing specimens provide considerably lower joint strengths than defect-free specimens. The decrease of the fatigue strength with increasing defect size can be shown, but the direct comparison of different defects is not possible with S-N-curves. Based on the experimental results and on theoretical investigations, a procedure was developed to estimate the lifetime of defect-free and defect-containing brazed joints based on the stress intensity caused by a defect.     

基于镀锡银钎料钎焊304不锈钢接头的腐蚀行为

为揭示304不锈钢钎焊接头的腐蚀行为,以BAg50CuZn钎料为基材,采用电镀扩散工艺制备AgCuZnSn钎料,对304不锈钢进行感应钎焊,在60 ℃,3.5% NaCl溶液中评价不锈钢接头的局部腐蚀性,借助扫描电镜对其腐蚀形貌进行分析. 结果表明,经NaCl溶液腐蚀后,钎缝与不锈钢界面出现较长的腐蚀沟;304不锈钢表面腐蚀较严重,存在大范围坑洞、裂纹等缺欠,而钎缝区几乎无腐蚀缺欠,优先被腐蚀的是富铜相. 随着腐蚀时间延长,钎缝和304不锈钢的腐蚀速率均呈现先升高后降低的趋势,钎缝腐蚀速率略低于母材;腐蚀2.5 h后,钎缝区和304不锈钢的平均腐蚀速率分别为0.098和0.104 g/(m2·h).     

铟对低银Ag-Cu-Zn钎料显微组织和性能的影响

研究了低银Ag-Cu-Zn钎料(ωAg≤20%)的熔化特性、铺展性能、钎料显微组织。以黄铜/304不锈钢作为母材,采用火焰钎焊方法,进行了搭接钎焊试验。结果表明,低银Ag-Cu-Zn钎料显微组织主要由铜基固溶体、银基固溶体、Cu Zn化合物相构成。In的添加降低了Ag-Cu-Zn钎料的固、液相线温度,改善了钎料润湿性能;添加In的低银Ag-Cu-Zn钎料在凝固过程中析出富In的银基固溶体,起到了固溶强化的效果,改善了钎焊接头的显微组织,从而提高了钎缝接头的力学性能。使用17Ag Cu Zn-1In火焰钎焊黄铜/304不锈钢,钎焊接头成形美观、组织致密、无缺陷存在,综合性能与含银量为25%的BAg25Cu Zn Sn银钎料的性能相当,节银效果显著。     

红外检测技术的研究与发展现状

红外无损检测(IRT)技术作为一种新的检测方法,可以检测材料、构件的内部缺陷,评估材料的应力状态以及实现疲劳寿命的快速预测,对设备进行运行状态监测和故障诊断。简述了IRT技术的基本原理,从缺陷检测、应力检测、疲劳分析、图像处理、检测监测应用等方面阐述了国内外IRT技术的研究以及应用现状。介绍了国内外IRT检测设备和检测标准、技术应用情况,并指出了该检测技术的发展趋势。     

Microstructure and mechanical properties of AlSiCu_(10-10) filler meter brazing 6063 aluminum alloy

AlSiCu_(10-10) flame brazing 6063 aluminum alloy was rearched,and microstructure and mechanical properties of brazed joints were tested in the experiments. The interfacial microstructures and brazing phases of brazed joints were analyzed by scanning electron microscopy( SEM) and X-ray energy dispersive spectroscopy( EDS). The strength of brazed joints was aquired by tensile test. The results show that the AlCu_2 and Mg_2 Si phases were formed in the brazing seam,the former is the brittle phase,the Mg_2 Si phases is considered to be the strengthening phase of the aluminum alloy,which can reduce the brittleness caused by AlCu_2. The average tensile strength of brazed butt joint was 115 MPa,and the average shear strength of brazed joint was 26 MPa. Finally,the fracture form and fracture morphology of the brazed joint were analyzed.     

A novel approach to compact braze aluminum alloys

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Calculation of contact stresses in wedge‐pressed welding

Research results of comparative analysis of the carrying capacity of brazed lap joints and brazed double-strap joints of different kinds are given. It is shown that brazed double-strap joints ensure the load-carrying capacity higher than lap joints. The constructions of brazed joints with disc straps as well as in the form of ball segments which have low material capacity are suggested.     

Ni-34Ti钎料钎焊TiAl合金接头界面结构及性能

采用Ni-34Ti共晶钎料实现了TiAl合金的钎焊连接,分析了TiAl合金钎焊接头的界面结构,重点研究了钎焊温度对接头组织及性能的影响规律.结果表明,Ni-34Ti共晶钎料主要由TiNi相和TiNi3相组成,钎料熔点为1 120 ℃.不同钎焊温度下获得的接头界面组织均呈现对称特征,无气孔和裂纹等缺陷,接头中主要形成了TiNiAl2,B2,TiNiAl和TiNi2Al四种物相.Al元素在钎缝中的快速扩散,促进了钎缝中Ti-Ni-Al三元化合物的形成.钎焊温度为1 180 ℃保温10 min条件下,TiAl合金接头获得了最大的室温抗剪强度87 MPa.剪切过程中,裂纹容易在富含TiNi2Al相的区域产生和扩展,大量脆性TiNi2Al相的存在对接头的性能是有害的.     

Thermal cycling behavior of alumina-graphite brazed joints in electron tube applications

Alumina was joined with graphite by active metal brazing technique at 895, 900, 905, and 910 °C for 10 min in vacuum of 0.67 mPa using Ti-Cu-Ag (68.8Ag-26.7Cu-4.5Ti; mass fraction, %) as filler material. The brazed samples were thermal cycled between 30 and 600 °C and characterized. X-ray diffraction results show strong reaction between titanium and carbon as well as titanium and alumina. Scanning electron microscopy and helium leak tests show that the initial and thermal cycled brazed samples are devoid of cracks or any other defects and hermeticity in nature. Brazing strength of the joints is found to be satisfactory.     

热障涂层无损检测技术研究进展

为提高发动机的涡轮前温度和热端部件服役寿命,热障涂层（TBCs）被广泛应用于燃气涡轮发动机。热障涂层具有多相、多界面和非均质特性,且其服役工况恶劣复杂。寻找一种可以表征涂层显微组织、缺陷、热物性、应力等反映涂层质量和剩余寿命的无损检测方法,对发动机的热端部件安全性和可靠性至关重要。文中综述了超声检测技术（UT）、声发射技术（AE）、红外热成像技术（IRT）、阻抗谱技术（IS）和光激发荧光压电光谱技术（PLPS）的原理以及其在热障涂层无损检测中的研究应用,并详细介绍了太赫兹时域光谱（THz-TDS）技术及其在热障涂层中的应用。最后总结了上述无损检测方法的检测能力,并对热障涂层无损检测方法进行展望。     

Ti-50Ni钎焊TZM与ZrCp-W接头界面组织及性能

采用Ti-50Ni(at%)钎料实现了TZM合金与ZrC_p-W复合材料的真空钎焊连接,通过SEM、EDS、XRD等方法分析了接头界面的微观组织结构,研究了钎焊温度对TZM/Ti-50Ni/ZrC_p-W接头界面组织及性能的影响。结果表明:钎焊接头的典型界面结构为TZM/Ti-Mo+TiNi_3+Mo-Ti-W/Ti Ni+TiNi_3+W(s,s)+(Ti,Zr)C/ZrC_p-W。随着钎焊温度的升高,Ti-Mo固溶体层宽度逐渐增大,线状条纹增多、增宽,组织逐渐粗大,晶界变圆滑;接头的抗剪强度随钎焊温度升高先升高后降低,当钎焊温度为1340℃,保温10 min时,接头获得最大抗剪强度为146 MPa。     

Interfacial Behavior and Its Effect on Mechanical Properties of C<Subscript>f</Subscript>/SiC Composite/TiAl6V4 Joint Brazed with TiZrCuNi

In order to characterize the interfacial behavior of brazed joints and offer theoretical basis for the applications of TiZrCuNi-based composite fillers, C_f/SiC composite and TC4 were brazed by TiZrCuNi filler, and the microstructures of joints versus temperature and versus holding time were systematically studied in this paper. The mechanical properties of brazed joints were measured and analyzed. The results showed that Ti(Zr)C, Ti₅Si₃, Ti₂Cu, TiNi, TiZrCu₂, Ti₂(Cu,Ni) and Ti(s,s) were the predominant compounds in the joints. Brazing temperature had a distinct effect on the microstructures of joints: with the increase of brazing temperature, the structure of brazed joints was reduced from four parts to three parts, and the wavy reaction layer became continuous and much thicker. While holding time had a similar but weaker effect on microstructures: with the extension of holding time, the reaction layer became thicker, but it was difficult to induce the decrease in the structural parts of joint. The thickness of reaction layer determined the mechanical properties of joints. The results were beneficial for the selection of reinforced phases and the design of composite fillers to obtain better mechanical performances. When the brazing temperature was 940 °C and the holding time was 25 min, the maximum shear strength of brazed joints attained a value of 143.2 MPa.     

Special features of brazing VZhM4 and VZhM5 single crystal alloys

The processes of recrystallization of single crystal nickel creep-resisting alloys in brazing were investigated. The methods of preventing recrystallization of the single crystal alloys are described. The microstructure of the brazed joints in the VZhM4 and VZhM5 alloys is investigated. The effect of heat treatment on the microstructure of the brazed joints in the VZhM4 and VZhM5 alloys is described and the strength of the brazed joints determined.     

一种钛基钎料钎焊TiAl合金接头的高温力学性能分析

采用自主研发的一种Ti-Zr-Cu-Ni-Co-Mo非晶钎料对TiAl合金进行钎焊连接，钎焊温度为1 000 ℃，时间为5 min，对所得的钎焊接头进行了高温抗剪强度和抗拉强度研究，并与母材强度进行了对比. 结果表明，钎焊接头在700 ℃高温下可长期服役，但剪切试验温度高于700 ℃后由于氧化物的生成和钎焊中心区显微组织发生变化导致剪切性能急剧下降，钎焊接头跟母材在不同拉伸试验温度下的抗拉强度随试验温度上升呈下降趋势，两者差距先减小后增大，分别在不高于600和800 ℃条件下仍能保持室温性能的80%以上.     

Brazing ferritic-martensitic reactor steels with an amorphous rapidly quenched nickel-based strip brazing alloy

A brazing alloy has been developed for brazing ferritic-martensitic steels. The technology for producing the brazing alloy based on nickel in the form of amorphous ribbons is described. Steels EP-450 DUO and EP-823 were brazed using the new brazing alloy. The relationships of the formation of brazed joints were determined. The results of brazing trials on models of fuel elements made of steels ChS-139 and EP-823 (EP-450 DUO) and the mechanical tests of the brazed joints (shear test) are presented.     

Effects of Cu, Si, Ni and rare earth elements on melting temperature and properties of Al-Si filler metals

The effects of Cu,Si,Ni and RE elements (RE=La and Ce) on the melting temperature of Al-Si filler metals were studied by orthogonal design method.The wettability of the filler metals and the shear strength of 6063 aluminum alloy joints brazed with the different filler metals were measured.The results show that the copper doping content has the most obvious effect on liquidus temperature (T_L) of the Al-Si filler metals and the effect of RE content on T_L is the least.Adding suitable Cu and Si can improve the wettability of the Al-Si filler metals.The shear strength of 6063 aluminum alloy joints brazed with the filler metals S10,S15 and S20,respectively,is better than that of the joints brazed with HL401 due to the improvement of microstructure.It can improve the shear strength of the joints by brazing with the Ni- or RE-doped Al-Si-Cu filler metals.     

钎焊填缝机理的研究-不等间隙钎焊时钎料填缝过程研究

钎焊接头的主要缺陷是夹气和夹渣.在六十年代初期,作者曾经指出:夹气,夹渣的形成是与钎料、钎剂的流动形式和过程有关.为了提高钎缝的钎着率.生产实践巳证明,采用不等间隙钎焊是有效的.在本文所提及的试验中,采用X 射线及工业电视观察钎料的动态过程并用摄影机将其记录.为了增强X 射线图象的反差,试验中主要采用S_a—P_b 钎料钎焊铜合金试件.钎焊是在水平位置下进行的.