挤压态AZ61镁合金真空扩散焊接试验研究

采用再结晶退火的方式,细化挤压态AZ61镁合金晶粒,并将细化后的镁合金进行真空扩散焊接研究。剪切强度试验结果表明,在连接压力为10MPa和真空度为18Pa的条件下,扩散温度为470℃、保温时间为90min时可得到最大剪切强度51.95MPa。试验分析表明,扩散温度和保温时间是扩散焊接接头性能的主要影响因素。对扩散焊接头及其周围区域进行显微硬度测量发现,焊缝处的显微硬度最大,偏离焊缝沿母材方向的显微硬度逐渐减小。     

不同工艺参数下SIMP钢三温工艺瞬时液相扩散焊接头的组织与性能

采用BNi2和Fe78Si9B13非晶合金箔作为中间层,对SIMP钢管进行三温工艺瞬时液相(TLP)扩散焊接,研究了不同等温凝固工艺参数(温度1 230,1 240℃;时间180,240s;压力8,9MPa)下接头的显微组织和力学性能。结果表明:等温凝固温度的升高或时间的延长均可以促进降熔元素的扩散,减少焊缝组织中脆硬相的生成,从而提高接头的抗拉强度、降低焊缝的显微硬度;较佳的等温凝固工艺参数为温度1 240℃、时间240s、压力9MPa,采用该参数焊接后接头组织为均匀马氏体,焊缝组织与两侧母材组织的差异很小,抗拉强度最高,为794MPa,拉伸断裂方式为韧性断裂。     

镀镍与镀铜对SiC_p/6063Al复合材料真空钎焊接头剪切强度的影响

采用表面金属化工艺在60%SiCp/6063Al复合材料表面制备镀铜层和镀镍层,然后对表面金属化处理前的复合材料进行真空加压钎焊,研究了镀镍和镀铜对复合材料钎焊接头剪切强度的影响。结果表明:复合材料表面镀层均与基体紧密结合;在570℃的钎焊温度下,随着保温时间延长,钎焊接头的剪切强度逐步增大;与表面镀镍及未镀金属的相比,表面镀铜复合材料接头的剪切强度更高,接头的剪切强度最高可达55.4 MPa,且其剪切断裂发生在钎料层和复合材料内部;镀镍会降低接头的剪切强度。     

超声诱导瞬间液相焊焊接以Ag-28Cu为中间层的过共晶Al-Si合金

在大气环境中,应用超声诱导瞬间液相焊的方法,焊接以Ag-28Cu为中间层的Al-50Si合金。研究了超声振动时间、焊接温度对接头微观结构演变和Si颗粒迁移的影响。分析了Si颗粒增强的完全固溶体接头的快速形成过程。阐述了剪切强度与超声振动时间和接头组织之间的关系。在520℃焊接温度下,超声振动仅3s,接头发生了界面冶金结合。超声振动15s时,获得了Si颗粒增强的完全固溶体接头。焊接温度对Ag、Cu和Al之间的相互扩散产生影响。随着温度的增加,原子扩散加快。由于超声在固-液体介质中的效应,使得基体金属与中间层表面的氧化膜得到快速破除,基体金属与中间层产生元素扩散。当扩散达到一定浓度时,基体金属与中间层发生冶金反应,形成Al-Ag-Cu三元共晶液相,并且Si颗粒迁移进三元共晶液相中。随着超声振动时间延长,在超声振动、压力作用下,三元共晶合金减少,直至完全消失,剩余的Al(Ag,Cu)固溶体保留在焊缝中,焊缝闭合,获得了Si颗粒增强的完全固溶体接头。Si颗粒的迁移和三元共晶合金的挤出影响接头的剪切强度。剪切强度随超声振动时间的延长而增加。超声振动15s的剪切试样,其断裂发生在基体金属侧,属于韧性断裂,接头剪切强度最高,达到约123MPa。     

保温时间对TLP扩散焊焊接TA2纯钛接头组织和性能的影响

以Cu-Ni-Sn-P非晶合金作为中间层材料,采用瞬时液相(TLP)扩散焊焊接了TA2工业纯钛,研究了保温时间对接头组织和性能的影响。结果表明:该接头结合处由残留中间层、等温凝固层和界面扩散层组成,随着保温时间的延长,残留中间层厚度减小,界面扩散层宽度增大,当保温5min后,接头处基本由羽毛状界面扩散区组成,宽度为25μm;接头剪切强度随保温时间的延长先增后降,保温时间为3min时达到最大,约180MPa,剪切断裂方式为脆性+塑性混合型断裂。     

多层复合钎料钎焊Ti(C,N)基金属陶瓷与45钢接头的组织

采用由Ag-Cu-Ti+Mo钎料、铜箔和Ag-Cu钎料组成的多层复合钎料,对Ti(C,N)基金属陶瓷和45钢在不同温度(890,920,950℃)和不同时间(10,20,30min)下进行了真空钎焊,根据接头截面形貌和剪切强度确定了最佳钎焊温度和保温时间,并分析了最佳工艺下钎焊接头的显微组织。结果表明:随钎焊温度的升高或保温时间的延长,Ag-Cu-Ti+Mo钎料与金属陶瓷间的界面反应层厚度增大,铜钛金属间化合物增多,两侧钎料区中的铜基固溶体增多,接头的剪切强度先增后降;最佳钎焊工艺为钎焊温度920℃、保温时间20min,此时接头剪切强度最大,从金属陶瓷向45钢,接头组织依次为Cu3Ti2+Ni3Ti金属间化合物,银基固溶体+铜基固溶体+钼+铜钛金属间化合物,铜,银基固溶体+铜基固溶体。     

耐高温陶瓷接头的合金化--用A1/Ti/A1复合层连接Si3N4陶瓷

用A1/Ti/A1复合层真空连接Si3N4陶瓷,研究了A1与Ti的匹配和工艺参数对接头显微组织及强度的影响。结果表明,当A1与Ti的匹配合理且采用适当的连接工艺时,A1与Si3N4和A1与Ti的相互扩散和反应可分别获得牢固的结合界面和以A13Ti耐高温相为主的焊缝金属,获得性能良好的陶瓷接头;Ti的厚度、连接温度和保温时间直接影响接头强度,当这些参数组合适当时,接头剪切强度在室温及600℃可分别达到89.4MPa和29.4MPa。     

采用Al-Si-Ti-Cu-In钎焊70% SiC_p/Al复合材料工艺研究

采用Al-Si-Ti-Cu-In钎料在不同工艺参数下对70%SiC_p/Al复合材料进行真空钎焊,通过扫描电镜(Scanning electron microscope,SEM)、能谱分析(Energy dispersive spectrometer,EDS)技术对接头组织形貌进行分析。结果表明:采用600℃、6MPa、保温1.5 h所得接头具有最大剪切强度90.17 MPa,断裂从母材开始,穿过钎料层,在另一侧母材中瞬断,其形貌具有韧、脆混合型断口形貌特征。焊缝微观组织主要包括蜂窝状Al基体、聚积的颗粒状富Ti、In相、环状富Si相和界面处的针状Al_4C_3脆性相。提高钎焊温度有利于焊缝中孔隙的收缩和减少,增加钎料对复合材料的润湿性,也有利于激发Ti的活性,阻碍Al_4C_3脆性相的生成。由于烧结体中孔隙变化规律和柯肯达尔效应的共同作用,使得焊缝中孔隙随保温时间的延长先减少后增加,若继续延长保温时间,孔隙终将消失。提高压力能有效改善焊缝致密度,阻碍Al_4C_3脆性相的形成,并改善其形态,能有效提高接头力学性能。     

低体积分数SiC_p/A356复合材料真空钎焊温度的确定

采用Ag47-Cu18-In17-Sn17-Ti1钎料,分别在560,570,580℃下保温30min对增强相体积分数为15%的SiC_p/A356复合材料进行真空钎焊,研究了钎焊接头的显微组织、显微硬度及抗剪强度,并确定了最优的钎焊温度。结果表明:在560~580℃温度区间进行真空钎焊获得的接头焊缝组织致密,钎料对基体铝合金和SiC颗粒都具有良好的润湿性,钎料中各元素在580℃下的扩散距离远大于在560℃下的;随着钎焊温度升高,焊缝中心及扩散区的显微硬度都逐渐下降;最佳的钎焊温度为560℃,在此温度下制备钎焊接头的抗剪强度可达51.8 MPa,焊缝中心与扩散区的显微硬度分别为99.4HV和110.7HV,接头的断裂方式表现为塑性断裂。     

基于ANSYS的FeCrAl合金真空扩散焊模拟

运用有限元分析软件ANSYS的APDL语言,编写了电热合金材料FeCrAl的真空扩散焊过程的数值模拟程序。建立了真空扩散焊过程中三维热一结构耦合场有限元计算模型,对给定温度下施加不同的压力载荷,计算该组耦合场模型焊接过程中应力应变分布。通过比较这些模型的应力应变分布得出最佳的温度、压力参数组合。摸索出最佳固相直接真空扩散焊的焊接工艺参数为焊件施压7MPa,950℃保温30min,1000℃保温20min,停止加热后卸压,随炉冷却。焊后试件的气密性试验及微观晶相组织显示,该工艺参数获得了良好的焊接接头质量。     

Investigation on overlap joining of AZ61 magnesium alloy: laser welding, adhesive bonding, and laser weld bonding

This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect.     

连接温度对T91／12Cr2MoWVTiB TLP连接接头组织和性能的影响

连接温度是完成瞬时液相扩散连接、保证焊接接头性能的关键参数,采用不同连接温度1210℃、1230℃和1250℃对T91／12Cr2MowVTiB进行瞬时液相扩散连接,连接压力为2MPa,保温时间为4min,结果表明,在1210～1250℃范围内,随着温度的增加,焊接接头的成分越来越均匀,连接区域的显微硬度分布逐渐趋于平缓,接头的力学性能也随之提高。     

Influence of high temperature diffusion bonding process parameters on mechanical and metallurgical characteristics of nickel superalloy to martensitic stainless steel

Welding of dissimilar metals is challenging because of the formation of microfissuring, strain age cracking and brittle intermetallic compounds. The above‐said problems can be avoided by controlled heating and cooling rates and the formation of beneficial intermetallic layers in the joint interface using solid‐state welding techniques such as diffusion bonding. This study investigates, the effect of diffusion bonding process parameters of dissimilar metals (AISI 410 martensitic stainless steel and nickel [Su 718] based superalloy). Fifteen joints were fabricated using different levels of bonding temperature (920–1,000°C), bonding pressure (10–18 MPa) and holding time (30–90 min). From this investigation, it is identified that joints fabricated at bonding temperature 980°C, bonding pressure 16 MPa and holding time 75 min yielded an extreme tensile strength (263 MPa) and hardness (450 HV) compared to the other joints. The tensile properties of the welded joints were assessed and associated with the microstructures. Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and X‐Ray Diffraction (XRD) analysis were used to estimate the metallurgical characteristics of the weldment. The EDS examination was supported out to analyses the interface composition and to decide the composition at the interface. Furthermore, a lot of δ phase precipitates were likewise found in the bonded region.     

Investigation of the effect of diffusion bonding parameters on microstructure and mechanical properties of 7075 aluminium alloy

In the present study, diffusion bonding of aluminium alloy (AA7075) sheet materials which are used especially in the automobile and aerospace industry has been investigated at temperatures of 425 and 450 °C and pressures of 2 and 3 MPa for 180 min in argon atmosphere. The microstructural and mechanical properties of bonding have been characterized with different welding parameters such as bonding temperature and pressure. The microstructure was characterized by light optical microscope, scanning electron microscope and energy dispersive spectroscopy, while the mechanical properties were determined by tensile-shear tests and microhardness tests. The results obtained are discussed from both the microstructural and mechanical points of view. It was observed in the microstructural investigations that the interfacial oxide layer decreased with increasing of the bonding temperature and pressure. The maximum shear strength was found to be 131 MPa for the Al 7075 sample bonded at 450 °C and 3 MPa for 180 min. It is shown that in certain extent, the bonding temperature and bonding pressure have great effect on the joint shear strength. With the increasing of bonding temperature and pressure, the shear strength of the joints increases due to diffusion of atoms in the interface. The strength achieved after bonding were dependent on interface grain boundary migration and on grain growth during the bonding process. The maximum hardness value of the Al 7075 sample bonded at 450 °C, 3 MPa for 180 min is 92.5 HV_0.2. Increasing hardness with increasing temperature can be attributed to the formation of metallic bond at high temperatures and pressures.     

Pulse current auxiliary TLP diffusion bonding of SiCp/2024Al composite sheet using mixed Al–Cu–Ti powder interlayer

Pulse current auxiliary transient liquid-phase (TLP) diffusion bonding of SiCp/2024Al composite sheet was investigated at 580 °C using mixed Al–Cu–Ti powder interlayer. The optimal process parameters were applied as follows: pulse current density of 1.15?×?10² A/mm², pressure of 0.5 MPa, vacuum of 1.3 ×?10^?3 Pa, and bonding time from 15 to 60 min. The bonding quality is evaluated by microstructure characterization and mechanical properties of the joints. The mechanism of pulse current auxiliary TLP diffusion bonding process is analyzed. The results indicated that the dense joints without cavity consisted of the Al-based solid solution, pure Ti, Al₂Cu, and TiAl₃ intermetallic phase. Microhardness of joints was obviously higher than Cu diffusion zone and substrate materials zone. The shear strength of the joints monotonically increased with bonding time. The maximum value exceeded 154.1 MPa in bonding time of 60 min. Pulse current generated Joule heat, high-temperature spark plasma, and electromigration, which guarantee the feasibility of bonding process and high-quality joint.     

面向即时检测芯片超声波精密键合的熔接结构及工艺参数

针对芯片即时检测(POCT)芯片对键合精度、键合强度、生产效率和生物兼容性的要求,基于超声波键合技术设计了结构化的导能筋布置形式和阻熔导能接头结构。研究了超声波键合时间和键合压力对微通道高度保持性能的影响,确定了精密超声波键合工艺参数。利用高精度显微镜、拉伸试验机和羊全血分别对键合后芯片的微通道高度、键合强度、微通道密闭性以及液体自驱动性能进行了测试。结果表明:所设计的导能筋布置形式合理可靠;利于芯片各功能的集成,阻熔导能接头结构能够较精确地控制键合后微通道的高度,键合精度达到2μm;全血驱动时间的极差在20s以内;所确定的键合工艺参数能够实现高强度的键合,键合强度不小于2.5 MPa。该熔接结构及工艺参数具有键合精度高、键合强度高、生物兼容性好和熔接均匀等优点,可应用于医用POCT芯片产品中。     

7075/6009铝合金层状复合板材的固溶时效热处理工艺

对7075/6009铝合金层状复合板材进行了不同的固溶时效处理,优化得到了该复合板最佳的热处理工艺,并对热处理后复合板的力学性能和拉伸断口进行了分析。结果表明:该复合板最佳的热处理工艺为485℃×30min水淬+175℃×8h炉冷,其抗拉强度为404MPa,屈服强度为364MPa,伸长率为15.3%;外层6009铝合金的拉伸断口上分布着大量韧窝,内外层合金间实现了良好的冶金结合。     

轴向拉力对铝合金拉拔式摩擦塞焊接头组织及力学性能的影响

拉拔式摩擦塞补焊是一种固相连接技术,具有接头强度高,焊后残余应力和变形小等优点,在航天领域具有潜在的应用前景。研究轴向拉力对2A70铝合金拉拔式摩擦塞焊焊接成形及接头性能的影响,并分析焊接缺陷、微观组织及断口形貌特征。结果表明,轴向拉力在20~30 kN范围内能够得到良好的焊缝成形;轴向拉力为20 kN时,结合界面存在未焊合缺陷;轴向拉力提高至22 kN及以上,未焊合缺陷完全消除;轴向拉力提高至28~30 kN时,塞棒与母材形成完好的冶金结合,焊接接头的抗拉强度可达到376 MPa,接头系数为83.6%。当轴向拉力较低时（22~25 kN）,结合界面上易出现弱结合缺陷,微观特征为沿结合界面断续分布的微孔,可导致接头抗拉强度和断后伸长率下降;焊接接头中,塞棒侧热影响区硬度值最低,分析表明该区域的晶粒形态和尺寸未发生明显变化,但θ'相部分溶解,θ相发生粗化,导致局部强度下降;断口形貌显示,在优化参数下断口呈现韧性特征。研究结果可为铝合金拉拔式摩擦塞补焊工艺及机理分析提供借鉴和参考价值。     

2mm厚1000 MPa级双相钢板电阻点焊工艺参数的优化

对2 mm厚国产汽车用1000MPa级双相钢板进行了不同工艺条件的电阻点焊,对各点焊接头显微组织、力学性能以及断口形貌等进行了分析,在此基础上优化了工艺参数。结果表明:在试验条件下,最佳点焊工艺参数为焊接电流12 kA,焊接时间12周波(0.24s),焊接压力3.5 kN;此条件下焊接接头的断裂方式以韧性断裂为主。     

气氛对AZ31B镁合金扩散连接接头性能的影响

针对AZ31B镁合金扩散连接中的气氛保护难题,利用VDW-15型扩散焊设备对厚度为1．0mm的AZ31B镁合金薄板进行了在不同连接气氛条件下的扩散连接。分析了不同气氛下试样的表面状态,对连接接头进行了剪切强度、显微硬度等力学性能测试,利用金相显微镜、扫描电镜对不同气氛下的扩散连接接头显微组织、断口形貌进行了分析,试验结果表明,在扩散连接过程中采用抽真空至4．0×10^-3Pa,再回充高纯氩气保护的方法得到了性能较好的接头,试样表面光洁,剪切强度为39．5MPa,断口分析表明其为脆性断裂。