Special Technologies Related to Electron Beam Welding

In order to improve the manufacturing quality of electron beam welding,some technologies are developed by using the special features of electron beam.Comparing with the conventional electron beam welding,the usage of multi-beam technology and micro-beam technology are introduced.In addition.the development of beam diagnostic system is also presented.

航空工业机械制造中的特种焊接技术探析

以航空工业机械制造中的特种焊接技术为切入点,分析了激光焊接、电子束焊接、惯性摩擦焊接、真空钎焊等技术的原理、工艺流程和应用情况,研究了技术的优势,为航空工业机械制造中的焊接技术提供参考.

Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties

High nitrogen stainless steel(HNS) is a nickel free austenitic stainless steel that is used as a structural component in defence applications for manufacturing battle tanks as a replacement of the existing armour grade steel owing to its low cost, excellent mechanical properties and better corrosion resistance.Conventional fusion welding causes problems like nitrogen desorption, solidification cracking in weld zone, liquation cracking in heat affected zone, nitrogen induced porosity and poor mechanical properties.The above problems can be overcome by proper selection and procedure of joining process. In the present work, an attempt has been made to correlate the microstructural changes with mechanical properties of fusion and solid state welds of high nitrogen steel. Shielded metal arc welding(SMAW), gas tungsten arc welding(GTAW), electron beam welding(EBW) and friction stir welding(FSW) processes were used in the present work. Optical microscopy, scanning electron microscopy and electron backscatter diffraction were used to characterize microstructural changes. Hardness, tensile and bend tests were performed to evaluate the mechanical properties of welds. The results of the present investigation established that fully austenitic dendritic structure was found in welds of SMAW. Reverted austenite pools in the martensite matrix in weld zone and unmixed zones near the fusion boundary were observed in GTA welds. Discontinuous ferrite network in austenite matrix was observed in electron beam welds.Fine recrystallized austenite grain structure was observed in the nugget zone of friction stir welds.Improved mechanical properties are obtained in friction stir welds when compared to fusion welds. This is attributed to the refined microstructure consisting of equiaxed and homogenous austenite grains.

AlCoCrFeNi_(2.1)高熵合金电子束焊接接头耐蚀性

为明确高熵合金焊接接头耐腐蚀行为,采用电子束方法对共晶双相AlCoCrFeNi_(2.1)高熵合金进行焊接,并运用电化学腐蚀方法研究了接头耐蚀性。结果表明,焊缝区域(FZ)自腐蚀电位相比母材(BM)提高0.16 V左右,耐蚀性增强,自腐蚀电流减小了一个数量级,腐蚀速率明显降低。焊接接头母材区域腐蚀坑呈纵深扩展趋势,而焊缝区域腐蚀坑呈横向扩展,并表现出明显的相选择性腐蚀现象。焊缝区域的晶粒细化显著,硬度升高,两相分布呈现密集的“网络”状,元素分布更加均匀,大角度晶界增加,这都增强了焊接接头的耐点蚀穿孔的能力。

Research on modeling of heat source for electron beam welding fusion-solidification zone

In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding （EBW） were summarized and introduced. The combined point-linear heat source model was brought forward and to simulate the welding temperature fields of EBW and predicting the weld shape. The model parameters were put forward and regulated in the combined model, which included the ratio of point heat source to linear heat source Qpr and the distribution of linear heat source Lr. Based on the combined model, the welding temperature fields of EBW were investigated. The results show that the predicted weld shapes are conformable to those of the actual, the temperature fields are reasonable and correct by simulating with combined point-linear heat source model and the typical weld shapes are gained.

50 Years Experience of the E.O.Paton Electric Welding Institute in Field of Electron Beam Welding

Studying the possibilities of electron beam welding (EBW) and the principles of construction of equipment for electron beam welding,led by academician Boris Evgenyevich Paton,began at the E.O.Paton Electric Welding Institute (PWI) in 1958.It resulted in development of the first laboratory-scale plant and welding of different small workpieces.One year later the method of electron beam welding turned out to be in great demand:in nuclear power engineering,in production of electric vacuum devices and liquid-fuel rocket engines.In 1961-1962 owing to effective coordination of work performed at government level,the first production machines for electron beam welding were put into operation at a number of branch enterprises.Within the next few years,application of electron beam welding became wider,first of all in the above mentioned industries,and simultaneously electron beam welding began to be accepted by aircraft and power engineering industry.In 1960-s PWI organized in Ukraine full-scale production of power units,developed by it (guns,power sources and control systems) on the basis of Sumy Factory of Electron Microscopes.72 complete sets of power source units of SP-30 type (25 kV,500 mА),330 complete sets of U-250А (30 kV,450 mА),320 complete sets of ELA-60 (60 kV,250,500 and 1000 mА) and ELA-120 (120 kV,1000 mА) were manufactured in different periods of time.On October 16th 1969 the first test of electron beam welding and cutting of metals was carried out in ?Soyuz-6? spaceship,that practically initiated the space technology.Testing was performed in Vulkan unit developed by PWI.Considering that in space X-radiation and difficulties with high-voltage insulation could eliminate the possibility of electron beam application,low accelerating voltage (not higher than 8 kV) was used.

Research on Electron Beam Welding of in situ TiB_(2p)/ZL101 Composite

Electron beam welding of in situ TiB2p reinforced aluminum composites was studied. The results show that no obvious pores or cracks is presented in the weld seam. The grains in the weld seam are remarkably refined and TiB2 particles distribute much more homogeneously than that in base metal. The hardness values of fusion zone and heat affected zone （HAZ） are both increased in comparison with that of base metal. There are no interface reactions between TiB2 particle and A1 matrix. This results supply the evidence that the novel TiB2p reinforced aluminum composites can be well joined with the electron beam welding.

TA15钛合金电子束焊接接头不同区域的疲劳裂纹扩展行为研究

对TA15电子束焊接接头的熔凝区和热影响区的显微组织、硬度、疲劳裂纹扩展速率、以及疲劳断口形貌进行了研究。结果表明:熔凝区的显微组织主要为粗针状α′马氏体组织,热影响区组织为α′马氏体组织+条片状的α相和β相,由接近熔凝区组织向母材组织过渡。母材的硬度较低,熔凝区平均硬度最高,热影响区的硬度介于两者之间。疲劳裂纹扩展速率高低与其显微组织密切相关,含塑性较好的片状α相较多的热影响区比熔凝区有较高的裂纹扩展抗力。

变形温度对异种钛合金电子束焊件显微组织与力学性能的影响

研究等温和近等温锻造变形温度对电子束焊接的异种合金(Ti2AlNb金属间化合物与TC11两相钛合金)焊接界面的显微组织与接头拉伸性能的影响。采用OM、SEM对焊缝区组织及拉伸度样断口进行观察,并对接头的拉伸性能进行研究。结果表明:电子束焊接的Ti2AlNb/TC11异种合金焊接界面的显微组织和接头的拉伸性能对变形温度敏感,在950℃变形后,位于焊缝一侧的Ti2AlNb合金中O相的含量大大增加,而位于焊缝另一侧的TC11合金为等轴α相和条状α相的混合组织,但焊缝上仍可见到断续相连的晶界α/α2相;在1010℃变形后,TC11合金具有魏氏体组织特征,这时焊缝上的晶界α/α2相完全断开;经950℃变形的试样在室温拉伸时,在Ti2AlNb合金中发生脆性断裂,这与O相不易协调变形有关,经500℃高温拉伸时,合金表现出较高的强度和较好的塑性,这是由于焊接界面的α/α2相颗粒较小,断裂位置转移到TC11钛合金上所致;经1010℃变形的试样表现出一定的强度,但是塑性严重下降,这与TC11钛合金的魏氏组织特征有关;因此,异种合金进行等温变形时,须严格控制变形温度。

Ti-60钛合金电子束焊接接头高温下的失效与变形行为

在600℃拉伸条件下,Ti-60钛合金电子束焊接接头的熔合区和热影响区抗变形能力强于母材区(BM),试样断裂于母材区.在600℃持久条件下,当加载应力(?)550 MPa时,接头变形以扩散控制的位错攀移为主,变形能力取决于显微组织中的板条边界密度,板条越细,边界密度越高,变形能力越大,断裂位置在接头熔合区;当加载应力接近或>550 MPa(母材区屈服强度附近)时,接头的变形以位错滑移为主,断裂位置在母材区.在600℃高周疲劳条件下,疲劳裂纹易萌生于接头母材区,裂纹形核位置在试样的表面或次表面.TEM观察表明,接头母材区的变形以贯穿板条集束的位错滑移为主;而接头熔合区中的位错则局限在单个马氏体板条内部,位错运动特征为攀移及少量滑移.

Ti合金电子束焊接三维温度场计算

提出了一种可考虑电子束焊接锁孔效应的三维温度场计算方法．在大量计算的基础上，讨论了Ｔｉ合金各计算参数的选取对电子束焊接温度场的影响，给出计算参数的选取原则和方法．计算结果表明，电子束焊接三维温度场解析计算方法不仅可准确预测焊缝的形状，并且还可对整个三维温度场计算分析，具有重要的工程应用价值．

150kV/30kW逆变式电子束焊接高压电源设计

针对150 k V/30 k W电子束焊接高压电源高电压、大功率输出的要求,低压电路采用IGBT(Insulated Gate Bipolar Transistor)逆变隔离直流电源与逆变全桥串联的主电路拓扑,高压电路由3组升压变压器与10倍压整流电路的串联结构并联组成;设计了高压采样电路、束流采样电路,以及双闭环控制电路.基于上述技术,实现了150 k V/30 k W高电压大功率输出.实验结果表明高压加速电源的输出线性度和束流输出线性度较好,同时高压稳定度和束流稳定度均在0.5%左右,能够满足电子束焊接的要求.

特厚钢板复合轧制工艺的实验研究

采用连铸坯直接轧制生产特厚钢板时，由于压缩比的限制，成品的厚度受到极大限制，很难生产产品厚度超过100mm的高质量特厚钢板。文中介绍了复合轧制生产特厚钢板的实验方法、工艺过程以及实验分析结果，包括复合界面金相组织观察、Z向抗拉强度及拉伸曲线、拉伸样断面收缩率、断口扫描分析、超声波探伤等。从金相组织看，界面结合率约99％～100％，从金相图片上已经找不到复合界面；Q345复合钢板的Z向平均抗拉强度为445MPa，平均断面收缩率为54．13％，拉伸试样在微观上表现为韧性断裂。从超声波探伤结果看，未出现明显缺陷回波。

电子束技术在高温合金中的应用

作为近年发展起来的先进加工技术,电子束技术具有高能量密度、高真空度、可实现精确控制等优点,其在高温合金中的应用已受到广泛关注。本文对电子束技术在高温合金的制备以及加工领域的研究与应用进行了综述,包括高温合金的电子束成型制造、高温合金的电子束精炼、电子束焊接、表面改性以及高温合金的电子束物理气相沉积,指出了目前电子束技术面临的挑战,并对电子束技术在高温合金领域的发展前景进行了展望。

变形温度对Ti2AlNb/Ti60双合金焊接接头组织性能的影响

研究了近等温锻造温度对Ti2AlNb/Ti60双合金焊接接头显微组织和力学性能的影响。结果表明:经不同温度近等温变形及相同热处理后,Ti2AlNb/Ti60双合金试样焊缝组织得到明显细化,强度和塑性得到提高,均高于基体Ti60合金;随着变形温度的升高,Ti60合金热影响区显微组织中初生等轴α相逐渐减少,β转组织增多,片状α相变短变粗。因此,合金的室温拉伸强度逐渐升高,塑性逐渐下降;变形温度为1010℃的试样,其焊缝熔合区显微组织较为均匀,塑性相B2含量较多,焊件室温及600℃高温拉伸均表现出较好的强度与塑性匹配。

电子束焊接动态过程仿真分析

基于有限差分理论和入射电子束服从高斯分布、在有限平板中匙孔理想化为旋转抛物面的基本假设,利用C++Buildel快速开发软件,在Windows NT平台上综合OpenGL图形接口及多线程技术开发了电子束焊接动态过程仿真系统EBWSIM.结果表明:该系统通过友好的图形用户界面可实现工艺参数、材料参数、约束控制、视点追踪等焊接过程与移动热源焊接匙孔及其三维温度场的可视化实时交互,并能够实时仿真电子束深熔焊各点的热循环、焊缝横截面、热影响区分布、焊缝钉形缺陷和匙孔曲面的形成过程,模拟结果与实验数据吻合较好.

电子束焊接技术研究及进展

简要介绍了电子束焊接技术的发展、基本原理以及应用范围。着重介绍了电子束钎焊、活性剂电子束焊接、电子束复合焊接、电子束填丝焊、局部真空电子束焊接、电子束扫描焊接等电子束焊接新技术在国内的研究现状,并对电子束焊接未来的发展做出了展望。

基于电子束能量分布控制的异种金属的焊接

在通用真空电子束焊机的基础上配置两对电子束偏转线圈、工控机、多功能数据采集卡、功率放大器以及虚拟仪器软件,构建一个电子束能量分布控制系统。利用该系统可对电子束扫描加热区域的能量密度分配进行离线编辑、计算和预测,并将电子束焊接过程中的三维能量分布实时显示在工控机屏幕上。对铌钛异种合金采用不对称热输入的扫描加热方式进行焊接,获得了铌、钛熔化量相当,焊缝形状对称的焊接接头。

组织不均匀性对TA15电子束焊接接头疲劳裂纹扩展的影响

采用一种水平切取疲劳试样的方法,研究厚板TA15合金电子束焊接接头的焊缝(WS)和热影响区(HAZ)的显微组织、硬度、疲劳裂纹扩展速率以及疲劳断口形貌。结果表明:在距焊缝顶端同样高度时,热影响区的组织不均匀性最大;从焊缝顶端到底部,焊缝的α′马氏体组织细化,但焊缝的组织不均匀性增大;受较高的组织不均匀性的影响,热影响区的疲劳裂纹扩展速率比焊缝的高,疲劳断口形貌反映了这种宏观上的差别。

5A06铝合金电子束焊接中镁元素的烧损行为

研究了5A06铝合金电子束焊接后熔池内镁元素的分布及其对焊缝硬度的影响,并分析了焊接参数对镁元素烧损行为的影响。结果表明:在同一熔池中随着深度的增加,镁元素含量增加,即烧损程度减小,同时显微硬度增大;随着加速电压和束流的增加,熔池熔深增加,镁元素烧损程度降低;随着焊接速度增加,镁元素烧损程度降低,熔深却减小。为减小镁元素烧损,在电子束焊接时可适当增加焊接的加速电压与束流,加快焊接速度。