Investigation on process and microstructure of Ti/Ni/Cu joints by electron beam welding

In this article, the electron beam welding of the Cu alloy （ QCrO. 8） with Ti alloy （TC4） sheet was processed and the joint microstructure as well as the welding process were studied. The results show that brittle reaction layer which was mainly composed of TiCu, Ti2Cu, Ti2Cu3 and TiCu2formed at the weld fusion line, regardless of welding on the middle or on the Cu side. The mechanical properties of the joint were severely deteriorated by the layer that tensile strength was only 89. 4 MPa for welding on the Cu side. The microstructure of the joint was improved with pure nickel as filler metal for the electron beam welding. The weld was mainly composed of solid solution. Intermetallic compound phase decreased signifwantly in fusion line compared with the joint without filler metal. The mechanical properties of the joint were obviously improved that the average tensile strength was 205.2 MPa and the bending strength was 413.3 MPa with O. 5 mm offset of electron beam on the Cu side.     

添加QCr0.8阻隔层的钛/钢电子束焊接接头组织与性能

采用1.5 mm厚QCr0.8铬青铜作为阻隔层进行了TA15钛合金与304不锈钢的电子束焊接,重点分析了焊接接头的横截面形貌、微观组织和力学性能。结果表明,焊缝中存在约0.5 mm宽的未熔QCr0.8阻隔层,实现了Ti元素与Fe元素的物理隔离,避免了Ti-Fe化合物的形成。铜/钢侧焊缝由铜基固溶体与铁基固溶体组成。而钛/铜侧焊缝中V元素的加入很好地抑制了Ti-Cu界面化合物的大量生成,焊缝组织由铜基固溶体、(Ti,V)基固溶体及少量Ti-Cu化合物组成,提高了该区域的强度和塑性。未熔铜阻隔层在热作用下发生软化,接头拉伸断裂发生在未熔的QCr0.8上,接头抗拉强度为293 MPa,为塑性断裂模式。     

钛合金电子束深熔焊钉尖缺陷形成的影响因素

钉尖缺陷是电子束焊接所特有的缺陷,对焊接质量造成严重影响.对于钉尖缺陷的形成机理,目前学术界还没有形成统一的认识.为了对钉尖缺陷形成机理进行研究,采用正交试验法进行了钛合金电子束深熔焊接试验,焊后对每条焊缝进行了X射线探伤,探伤结果显示钉尖缺陷只存在于未熔透焊缝中,钉尖为不规则狭缝状,根部呈圆形.利用光学显微镜和扫描电镜结合能谱分析对钉尖缺陷的形成机理进行了研究.结果表明,电子束脉动是钉尖缺陷产生的直接原因,高饱和蒸气压金属蒸气的存在加剧了钉尖缺陷产生的倾向,是钉尖缺陷产生的重要内在动因.     

Interfacial reaction product and mechanical properties of the electron beam brazed K465 Ni-based superalloy joints

Ni-based superalloy K465 is brazed with BNi-2 filler metal by vacuum electron beam brazing (VEBB). In process of VEBB, effects of processing primary parameters on shear strength of joints are investigated. Microstructure of the brazed joint with BNi-2 filler metal is studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that the structure of brazed seam consists of a large amount of Ni-based γ solid solution, Ni3Al (γ′), Ni3B, WB, CrB, and a small quantity of WC, NbC. The maximum shear strength of the joint is 398 MPa when the beam current of welding is 2.6 mA, heating time is 480 s and focused current is 1 800 mA.     

TiAl/TiAl和TiAl/TC4真空电子束焊接头组织结构及焊接性

对TiAl自体及TiAl／TC4异体对接接头进行了不同焊接参数下的电子束焊接试验。通过光学金相、能谱分析及SEM断13形貌分析等方法对TiAl自体焊及TiAl／TC4异体焊接头区的显微组织结构及断裂性质进行了分析。研究结果表明,TiAl／TiAl焊缝为树枝状TiAl铸态组织,TiAl／TC4焊缝为支晶近Ti3Al铸态混合组织;接头拉伸断裂为脆性解理断裂,接头的力学性能对接头显微组织非常敏感;TiAl／TC4接头拥有比TiAl／TiAl接头较好的可焊性。     

钢侧束偏量对QCr0.8/1Cr21Ni5Ti电子束焊接头组织性能的影响

对QCr0．8与1Cr21NiSTi异种材料对接接头进行了钢侧束偏量电子束焊接试验,采用光学金相和扫描电镜断口分析方法对接头的组织结构和连接状况进行了研究。研究结果表明,钢侧束偏量offset。的改变对接头组织结构的影响显,随offset。的增加,接头组织均匀化程度提高,焊缝中α ε相的体积比增大,但由于不均衡热输入及铬青铜的快速热传导性,导致铜侧母材的熔合状况不良。进一步的拉伸试验结果表明,随offset。的增加,接头强度急剧下降;QCr0．8／1Cr21NiSTi偏钢电子束焊接接头的总体强度不高。     

Microstructure and mechanical properties of butt joints of QCr0.8/1Cr21Ni5Ti equal-thickness dissimilar materials by electron beam welding

0　IntroductionThedissimilarmaterialsjointisusuallyemployedinindustrialproductiontomakefulluseofthematerialsperformanceadvantageorspecialstructuralpurpose.Thedissimilarmaterialsjoiningtechnologybetweencopperalloyandstainlesssteelhasattractedagreatdealofattention,botheffectiveassemblageputweldedcomponent’scoolingandhighstrengthintoeffect.However,becauseofbothmaterialschemicalandthermophysicalperformancedifferenceandcomplexityofweldingmetallurgy,thedefectsuchaspore,crackandbrittlephaseandarathe…     

LF2铝合金与Q235钢加入中间Cu层电子束焊接接头组织及形成机理

对2 mm厚的LF2铝合金和Q235钢平板试件进行了加入中间过渡层金属Cu的电子束对接焊接试验,利用光学金相、扫描电镜及能谱分析等方法研究了接头各区域的组织结构和成分分布.结果表明,接头可分为三个焊缝组织区域,其中靠近钢侧的焊缝区主要为Fe基固溶体,并含有少量金属间化合物;靠近铝侧的焊缝区为含有Fe-Al系及Al-Cu系金属间化合物的Al基固溶体;焊缝中部区为呈层带状分布的多种Fe-Al以及Al-Cu脆性金属间化合物混合区.分析认为虽然引入了铜过渡层,但在焊缝中依然有较多金属间化合物生成,特别是焊缝中部区域上,呈连续层带状分布的多种脆性金属间化合物的产生是影响接头强度的主要因素.在对接头组织结构分析的基础上,建立了描述LF2/Q235异种金属电子束对接接头形成过程的物理模型.     

W6高速钢/16Mn钢电子束焊接接头组织及性能分析

高速钢作为一种高硬度、高耐磨性和高耐热性特殊工具钢,应用于刀具、模具及特殊结构件上时,往往需要结合异种钢使用. 但高速钢焊接工艺研究仍不成熟,焊接中产生的裂纹与碳化物缺陷是制约高速钢应用的主要因素. 文中通过对W6Mo5Cr4V2高速钢与16Mn钢预置镍填充层后进行电子束焊接. 结果表明,镍中间层的引入有效的抑制了高速钢侧热影响区的开裂,接头呈不对称“漏斗形”. 焊缝组织主要由镍基固溶体与少量M₂C碳化物构成,焊缝中无马氏体组织,其焊缝平均硬度为185 HV;接头抗拉强度达到378 MPa,为16Mn侧母材抗拉强度的75%. 拉伸断口断裂于距W6侧熔合线0.8 mm处的热影响区,为准解理断裂.     

电子束原型制造技术研究进展

阐述了电子束送丝快速成型及粉末烧结技术的基本原理与特点,综述了电子束原型制造作为一种新型快速的成型方法,在国内外相关领域的主要研究成果及取得的进展,展望了电子束原型制造的未来发展与可行的研究方向,指出电子束原型制造装备的研制、电子束增量成型冶金及工艺机理、成型自动化控制研究是该领域发展的重要研究方向.