TC4钛合金真空钎焊接头显微组织分析

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TC4钛合金激光焊接接头高温热处理后的显微组织研究_林海凡

α′
(a) 焊缝整体
(b) 熔合线
β
100 μm
CPS→
α′ α′
α′ β
β
20
40
60
80
100
2θ / (°)
图 2 焊缝的 XRD 分析图 Fig.2 XRD pattern of weld bead
图 3 1193 K 保温 50 min 空冷的显微组织照片 Fig.3 Microstructure of the sample treated at 1193 K for 50 min
收稿日期：2010-08-04 作者简介：林海凡（1983- ），男，硕士研究生，从事工厂工程设计（热
处理和焊接工艺设计）；电话：15267065843； E-mail：lhf_8211@
在消除焊接残余应力方面， [5-7] 而对于激光焊接接头高温热处理后的显微组织的研究并不多见。为充分发挥钛合金的性能潜力, 有必要研究焊后热处理对接头的影响。本文通过研究 TC4 合金激光焊接接头高温热处理后的显微组织和显微硬度, 分析了其高温热处理前后激光焊缝组织及力学性能的变化。
[2] 王永梅，李渭清，马龙，等．热处理工艺对 TC4(ELI)钛合金组织和力学性能的影响 [J]．稀有金属材料与工程， 2005， 34 (3)：355-357.
距焊缝中心距离 / mm
图 5 接头显微硬度分布 Fig.5 Microhardness of welded joints before
and after heat treatment

TC4钛合金喷嘴真空钎焊工艺研究

焊缝中心的灰白包突起相Ｄ相比，浅灰色Ｂ的目架
可见，图５ａ中的Ａ相主要南＿和Ａ两种元素构成，ｒｉｌ
还有极少量的Ｎ和Ｃｉｕ等元素，ｒ此认为灰白色块大ｌ状相Ａ主要为ｒ和Ａ的化合物相。Ｂ和Ｄ相的形态ｒ；１
和元素组成较相似，主要由．元素构成，并在其中ｒｊ溶解少量的Ａ、Ｖ、Ｎ、Ｃ１ｉｕ和ｚ元素，但与更靠近ｒ
料与母材之问的界面反应程度较低，难以实现有效
的冶金结合，因而接头强度较低。而当保温时间过
图２界面分析试件装配
长时，界面反应过于激烈，界面上生成了过多的金
２．试验结果及分析
（）钎焊接头的抗拉强度卣先是钎焊温度对１接头抗拉强度的影响：保温时问为１ｍｉ，不同钎焊５ｎ温度对接头强度的影响如图３所示。从图中可以看
：
面是一个较宽的区问。
嘧如
１
（）整个界面ａ
≥
血ｌ赴
ｆ
（）Ｎ、Ｃｂｉｕ和ｚ兀素ｒ
罔６Ｔ４Ｃ钉焊接又线扫捕结果（＝４￣ｆ１ｍｎＴ９０Ｃ、＝５ｉ）
元素扩散的速度最快
表３中列出了罔５中Ｔ４合金接头各反应产物Ｃ中元素含量巾Ａ～Ｄ各点ＥＳ分析的结果：从表３巾Ｄ

TC4钛合金线性摩擦焊接头组织及性能研究

能等方面，其中对接头性能的研究主要集中在室温
线性摩擦焊是将两个待焊件表面相互接触并加
以一定的压力，同时使两接触面以一定频率和振幅
呈直线往复运动产生摩擦热实现焊接。线性摩擦焊基本过程是：一个工件被夹具固定，另一个构件与
要应用方向之一是用作整体叶盘的制造和修复，与传统机械加工相比采用线性摩擦焊制造整体风扇叶盘可节约８％的金属材料，从而节约大量的钛合８
金，采用线性摩擦焊还可以对损坏的整体叶盘单个
焊接
性摩擦焊技术已经成熟，采用线性摩擦焊制造的钛
收稿日期：２１０２０２— ４— ０
图１线性摩擦焊焊接试板
Ｆｉ．１Ｓｃｍｅｓｆｒｌｎｒｃｉｎｗｅｄｎｇｔｓｇｐｅｉｎ０ｉｅｆｔｏｌｉｅｔｉ
小；塑性变形区域原始片层组织被压扁拉长，与焊接振动方向呈近平行的流线状。关键词：钛合金；线性摩擦焊；组织；力学性能
１前
言
合金整体叶盘已经在航空发动机上得到应用 ¨引。我，国线性摩擦焊技术研究起步较晚，目前的研究主要集中在线性摩擦焊相关的工艺、接头组织、接头性
作者简介：张学军（９９）１６一，男，高级工程师。
钛工业进展
３０

TC4钛合金电子束焊接头微观组织结构和演变分析

TC4钛合金电子束焊接头微观组织结构和演变分析邓云华;关桥;史一宁;郭振玺【摘要】Microstructure of electron beam welded TC4 joint is investigated through OM, SEM, EDS and EBSD analysis. Results show that the microstructure in the fusion zone (FZ) and heat affected zone (HAZ) change signiifcantly after electron beam welding. The FZ is made up of coarse columnar grains with matensite α’, and the misorientation angle distribution concentrates near 62.5°,which represents part α/α boundaries are formed from one parentβgrain. Due to the we lding thermal cycle, the original texture microstructure is transformed into equiaxed grains in HAZ near base metal (BM). The micro-structure of HAZ near BM is composed of originalα, origi-nalβ, blockαand few matensiteα’, and the misorientation angle distr ibution indicates partα/αboundaries are devel-oped from two differentβgrains. HAZ near FZ is made up of matensiteα’ and blockα, and the misorientation angle distribution represents partα/αboundaries are formed from one parentβgrain..%利用OM、SEM、EDS和EBSD方法对TC4合金电子束焊接头的微观组织结构进行了分析。

TC4钛合金TIG焊接头组织及力学性能

图３ｂ所示，弯曲试样裂纹基本都出现在
试件出现裂纹后，有的断开，有的并未断
，
４。６，９弯曲变形的程度较大，，５，７
８弯曲变形程度较小。
（）熔合区晶粒粗大是造成接头性能降低的主要２
原因。因此，选取合适的热输入，避免熔合区、热影响区晶粒粗大是获得优良接头的重要条件。
总量
１０００．０
＿．试样断面与主应力方向垂直，符合脆性
试件基本看不到明显的塑性变形，说明接：；肉眼观察试样的断口都比较平整，呈差
４结论
（）采用焊接电流７１０Ａ、焊接速度８ｍｈ和氩气／流量１／ｎ的工艺时，Ｔ４板材ＴＧ焊对接接头性１ｍｉＬＣＩ能较其他工艺条件所得接头的性能好，该接头抗拉强度达到母材的８．％，断后伸长率为母材的１．５１９６％。
收稿日期：２１— １Ｏ００１一６
磨制接头金相试样，并用蔡司光学显微镜观察接头显
ｃｎｌｇ１０Ｎ．Ａｒ２１ｈｏｏｙＶｏ４ｏｐ．０．４１
・验与研究・ｌ试７
头组织粗大；或者是焊接过程中，接头未
作者简介：侯继军（９５）１８一，男，内蒙古包头市人，硕士研究生，主
要从事钛合金ＴＧ焊工艺研究．Ｉ

TC4钛合金真空钎焊接头显微组织分析

TC4钛合金真空钎焊接头显微组织分析作者：徐龙勇来源：《价值工程》2013年第22期摘要：采用Ag-Cu-Ti钎料对TC4钛合金进行真空钎焊；采用金相分析、扫描电镜对钎缝的组织结构、元素分布情况进行分析，并对焊件的整体力学性能进行拉伸测试。

结果表明，TC4合金板真空钎焊搭接接头处抗剪强度在200MPa以上，钎焊接头处总体的力学性能优于母材；钎缝与基体相临的部位析出了弥散相，钎缝处有Cu的固溶体析出；焊接接头中的主要元素Ti、Al、V、Ag、Cu呈规律性分布，钎缝及扩散区域得到以细小笋状的方式生长的Cu基固溶体，是为Ag-Cu共晶组织。

Abstract： Vacuum brazing of TC4 was carried out with Ag-Cu -Ti filler metal. Organizational structure， element distribution of brazed joints were investigated by means of scanning electron microscopy and metallographic microscope， and the joint whole mechanical property was determined by tensile testing method. The results show that shear strength for the brazing joint of TC4 titanium alloy is above 200MPa and whole mechanical property of the brazing joint are better than base metal. Dispersed network phase form between base metal and brazing seam， and Cu-based solid solution separate out in the brazing seam. Ti， Al， V， Ag and Cu of the brazing joint were regular distribution. Ag-Cu eutectic structure of brazing seam and diffuse region were grown by slender and small bamboo shoots mode.关键词： Ag-Cu-Ti；真空钎焊；显微组织Key words： Ag-Cu-Ti；vacuum brazing；microstructure中图分类号：P755.1 文献标识码：A 文章编号：1006-4311（2013）22-0048-030 引言TC4合金中钛的含量很高，钛是活性很强的金属材料，在高温下容易与N2、H2、O2反应，并同其它许多金属反应生成脆性金属间化合物，在600℃氧与钛发生强烈反应，800℃氧化膜开始向钛中溶解扩散，氮与钛在高温下则形成脆硬的氮化钛，对钛的塑性影响较大，氢的存在则由于γ（TiH2）相析出，也同样使其塑性、韧性降低[1]。

TC4钛合金的TIG焊接工艺及缺陷分析

(2) 在焊接过程中 ,随焊接电流变化 ,容易出现气孔、夹杂、裂纹等缺陷。
(3) 焊接电流选择合理 ,则焊后试样的抗拉强度、延伸率与母材相当。
参考文献
1 草道英武编. 程敏 ,赵克德 ,屈翠芬译. 金属钛及其应用. 北京 :冶金工业出版社 ,1989.
2 陆树荪 ,顾开道 ,郑来苏. 有色铸造合金及熔炼. 北京 :国防工业出版社 ,1983.
图 3a 是焊接电流在 75 A 时产生的焊缝中的夹杂
图 3b 为焊接电流在 160 A 时焊缝内的夹杂物。出现这样的夹杂很可能是由于电流密度较大 ,导致焊丝熔断 ,或者钨极尖端烧损造成的 ,通过能谱分析得知 ,杂质中 W 含量很高 ,因此可以断定杂质是由钨极烧损造成的 ,所以在焊接前修磨钨极时端部不能太尖 ,以防钨烧损[6] 。 2. 3 裂纹分析
其应用带来一定困难[3～5] 。本论文的目的是通过一系列的焊接试验来研究分析 TC4 钛合金 TIG 焊工艺及焊接时出现的各种焊接缺陷。
1 试验过程
1. 1 试验材料本试验使用的母材为 4 mm 厚 TC4 板材 ,焊接材料
选用了 <2. 5 mm 的 TC4 标准焊丝 ERTi - 6Al - 4V ,具体化学成分如表 1 所示。
表 3 试样力学性能焊缝延伸率 ( %) 6. 8 7. 3 6. 5 6. 2 7. 1
焊缝硬度 ( HV) 359 330 347 355 343
热影响区硬度 ( HV) 342 318 329 341 335
3 结论
(1) 用 ERTi - 6Al - 4V 焊丝焊接 TC4 合金最佳焊接电压为 15～25 V ,焊接电流为 100～120 A ,焊缝区为交叉片状组织和针状组织 ,其硬度比母材高 ,热影响区组织明显长大。

TC4钛合金真空钎焊接头显微组织分析

ａｎｄｗｈｏｌｅｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｙｏｆｔＩｌｅｂｒａｚｉｎｇｉｏｉｎｔａｒｅｂｅｔｔｅｒｔｈａｎｂａｓｅｍｅｔａ１．Ｄｉｓｐｅｒｓｅｄｎｅｔｗｏｒｋｐｈａｓｅｆｏｒｍｂｅｔｗｅｅｎｂａｓｅｍｅｔａｌａｎｄ
关键词：Ａｇ — ｃｕ — Ｔｉ；真空钎焊；显微组织
Ｋｅｙｗｏｒｄｓ：Ａｇ — — Ｃｕ — — Ｔｉ；ｖａｃｕｕｍｂｒａｚｉｎｇ；ｍｉｃｒｏｓｔｒｕｃｔｕｒｅ
中图分类号：Ｐ７５５．１
徐龙勇ＸＵＬｏｎｇ — ｙｏｎｇ
（威海华东重工有限公司，威海２６４２０７）
（ＨｕａｄｏｎｇＨｅａｖｙＭａｃｈｉｎｅｒｙＣｏ．Ｌｔｄ．，Ｗｅｉｈａｉ２６４２０７，Ｃｈｉｎａ）
ｂｒａｚｉｎｇｓｅａｍ，ａｎｄＣｕ－ｂａｓｅｄｓｏｌｉｄｓｏｌｕｔｉｏｎｓｅｐａｒａｔｅｏｕｔｉｎｔｈｅｂｒａｚｉｎｇｓｅａｍ．Ｔｉ，Ａ１，Ｖ，ＡｇａｎｄＣｕｏｆｔｈｅｂｒａｚｉｎｇｊｏｉｎｔｗｅｒｅｒｅｇｕｌａｒ
ｄｉｓｔｒｉｂｕｔｉｏｎ．Ａｇ — Ｃｕｅｕｔｅｃｔｉｃｓｔｕｃｒｔｕｒｅｏｆｂｒａｚｉｎｇｓｅａｍａｎｄｄｉｆｆｕｓｅｒｅｇｉｏｎｗｅｒｅｇｒｏｗｎｂｙｓｌｅｎｄｅｒａｎｄｓｍａｌ１ｂａｍｂｏｏｓｈｏｏｔｓｍｏｄｅ．

TC4钛合金钎焊工艺与接头组织性能研究

TC4钛合金钎焊工艺与接头组织性能研究淮军锋;郭万林【期刊名称】《焊接》【年(卷),期】2016(000)005【摘要】TC4钛合金是一种中等强度的α-β型双相钛合金,具有优异的综合性能,长时间工作温度可达到400℃.文中针对TC4钛合金复杂精密构件设计制造可能的需求,采用Ti-21Cu-13Zr-9Ni钎料对TC4合金进行了真空钎焊.通过扫描电镜与能谱等手段,对钎焊接头界面的元素分布及钎焊接头的组织进行分析;同时测试了接头室温和高温力学性能.试验结果表明,采用Ti-21Cu-13Zr-9Ni钎料钎焊TC4钛合金合理可行;采用Ti-21Cu-13Zr-9Ni钎料930℃/10 min钎焊TC4钛合金的钎焊接头,通过930℃/40min扩散处理后,钎焊接头室温、高温400℃和600℃抗拉强度分别达到930 MPa、610 MPa、400 MPa;基本等强于同一热循环的母材抗拉强度.采用Ti-21Cu-13Zr-9Ni钎料930℃/10 min钎焊TC4钛合金的钎焊接头,通过930℃/40 min扩散处理后,其钎焊接头的冲击性能有明显提高.【总页数】4页(P57-60)【作者】淮军锋;郭万林【作者单位】北京航空材料研究院焊接与塑性成型研究所 100095;北京航空材料研究院焊接与塑性成型研究所 100095【正文语种】中文【中图分类】TG454【相关文献】1.TA15钛合金钎焊工艺与接头组织性能研究 [J], 淮军锋;郭万林;李天文2.钎焊工艺对钛钎焊石墨与TZM合金接头组织性能的影响 [J], 徐庆元;李宁;熊国刚;张伟;赵伟3.基于正交实验的TC4钛合金激光焊接头组织性能优化研究 [J], 许爱平; 董俊慧; 甄邵杨; 张艺程4.TC4钛合金真空电子束焊焊接接头组织性能与腐蚀行为研究 [J], 陈启斌5.焊接功率对TC4钛合金激光焊接头成形与组织性能研究 [J], 许爱平;董俊慧;甄邵杨;张艺程因版权原因，仅展示原文概要，查看原文内容请购买。

TC4钛合金两种显微组织的紧固孔原始疲劳质量研究

TC4钛合金两种显微组织的紧固孔原始疲劳质量研究李华;贺飞;马英杰;雷家峰;景绿路;刘羽寅【摘要】利用标识载荷试验技术,将具有两种不同显微组织TC4钛合金分别在三种应力水平下进行疲劳试验,在光学显微镜下对疲劳裂纹扩展断口进行观察,获得裂纹扩展过程中不同循环周次下的裂纹长度,以此建立了表征TC4钛合金原始疲劳质量的通用EIFS分布.研究结果显示钛合金双态组织比片层组织具有更好的原始疲劳质量,双态组织具有较高的疲劳裂纹萌生寿命及裂纹扩展系数.此外还分析了双态组织中添加标识载荷的疲劳断口形貌,认为其疲劳断口标识线的形成是由于加入标识载荷后,应力强度因子范围发生变化,导致疲劳裂纹扩展过程中断裂模式发生改变,从而在断口上形成了可判读的标识线.%Fatigue crack growth a-N data of TC4 titanium alloy with bimodal and lamellar microstructure was obtained from fracture surface by marker load technique. Based on three different stress levels, the general distribution of equivalent initial flaw size ( EIFS) was established to describe the initial fatigue quality (IFQ) of the two microstructures. The results show that, compared with lamellar structure, the IFQ of TC4 titanium alloy with bimodal structure is a high level titanium alloy, in which the IFQ is affected by both the initiating cycles of fatigue crack and the crack propagating coefficient. The fracture morphology in bimodal microstructure by marker load technique was analyzed. It was revealed that the model of fatigue crack propagation changed after the marker load added, which lead to the readable marker line in fracture surface.【期刊名称】《航空材料学报》【年(卷),期】2013(033)002【总页数】6页(P81-86)【关键词】钛合金;紧固孔;原始疲劳质量;标识载荷;断裂模式【作者】李华;贺飞;马英杰;雷家峰;景绿路;刘羽寅【作者单位】中国科学院金属研究所,沈阳110016【正文语种】中文【中图分类】V223;V215.5现代航空业飞速发展，为了提高飞机的机动性能和燃油效率，对飞机结构减重提出了更为迫切的要求［1］。

TC4钛合金K-TIG焊接接头的显微组织及力学性能

Trans. Nonferrous Met. Soc. China 31(2021) 416−425Microstructure and mechanical properties ofTC4 titanium alloy K-TIG welded jointsShu-wan CUI1,2, Yong-hua SHI2, Cheng-shi ZHANG31. School of Mechanical and Transportation Engineering,Guangxi University of Science and Technology, Liuzhou 545006, China;2. School of Mechanical and Automotive Engineering,South China University of Technology, Guangzhou 510640, China;3. SAIC Liuzhou Automobile Transmission Co., Ltd., Liuzhou 545006, ChinaReceived 21 March 2020; accepted 23 December 2020Abstract: The 12 mm-thick Ti−6Al−4V (TC4) titanium alloy plates were welded using keyhole tungsten inert gas (K-TIG) welding at various heat inputs. The microstructure, grain boundary (GB) characteristics and mechanical properties of the weld metal zone (WMZ) were analyzed. The test results show that the K-TIG welds are well formed, and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm. When the heat input gradually increases, α laths increase in length, and α′ phase and residual β phase are reduced. The electron backscatter diffraction (EBSD) test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input. The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm. The impact toughness of the WMZ increases as the heat input increases.Key words: K-TIG welding; heat input; α′ phase; high-angle grain boundary; Charpy impact fracture surface1 IntroductionThe Ti−6Al−4V (TC4) titanium alloy is a veryimportant structural material and is currently widelyused in the field of marine engineering [1−3]. Forexample, it is widely used in the hull constructionof condensate tankers. CUI et al [4] reported thatthe TC4 titanium alloy was a two-phase titaniumalloy comprising the α+βphases and had theadvantages of low density, high strength and highcorrosion resistance. Welding is an indispensableprocess technology in the processing andmanufacturing of titanium alloys. Titanium alloyshad a strong activity in the molten state, and theyreacted readily with various substances duringwelding, which deteriorated the performance of thewelded joints, as reported by DING and GUO [5].Keyhole tungsten inert gas (K-TIG) welding is aTIG welding method with keyhole mode. Incontrast to TIG welding, it can weld titanium alloyplates that are less than 16 mm in thickness in asingle-pass welding without filling the weldingmetal or opening the groove [6]. The heat-affectedzone (HAZ) of the K-TIG welded joint is relativelynarrow, and the welding deformation is relativelysmall [7,8]. Therefore, K-TIG welding enablesdouble-sided forming of single-sided welding. For acertain thickness of TC4 titanium alloy, K-TIGwelding can save welding metal, improve weldingefficiency and reduce cost. CUI et al [4] alsopointed out that K-TIG welding was a veryeconomical method for welding medium-thickTC4 titanium alloys. However, during the weldingCorresponding author:Yong-huaSHI;Tel/Fax:+86-20-87114407;Mobile:+86-135********;E-mail:****************.cnDOI:10.1016/S1003-6326(21)65506-11003-6326/© 2021 The Nonferrous Metals Society of China. Published by Elsevier Ltd & Science PressShu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 417 thermal cycle, the microstructure of the titaniumalloy welded joint has undergone significant changes, which has a certain impact on the mechanical properties of the welded joint. Therefore, it is very important to study the microstructure of titanium alloy welded joints.At present, researchers have studied the microstructure of titanium alloy welded joints with different welding methods. WANG et al [9] discussed the microstructure and mechanical properties of TC4 titanium alloy electron beam welded joints. They reported that the inhomogeneity of microstructure in the welded joint was formed due to different microstructures of base metal (BM). LATHABAI et al [10] welded commercially pure titanium with K-TIG welding. They proved that 4 mm/s was the best choice for the welding speed of commercially pure titanium workpieces with a thickness of 12.7 mm. ROSELLINI and JARVIS [11] also used the K-TIG welding method to weld titanium alloy tubes. They showed that the mechanical properties of the K-TIG weld metal zone (WMZ), such as the tensile properties, impact properties and microhardness values, were almost the same as those of conventional TIG WMZ. CUI et al [4] welded 12 mm-thick TC4 plates by using K-TIG welding. They studied the microstructure and texture of the BM, HAZ and WMZ of TC4 K-TIG welded joints. SQUILLACE et al [12] indicated that during the welding thermal cycle, the microstructure of TC4 titanium alloy welded joints changed significantly. Microstructural changes are needed to improve the tensile properties and impact properties of K-TIG welded joints. However, during the K-TIG welding process, heat input has a certain influence on the mechanical properties and microstructure of the TC4 titanium alloy K-TIG WMZ, and research on this topic is limited. In this work, TC4 titanium alloy plates were welded with various heat inputs by the K-TIG welding system. During the K-TIG welding process, filling metals or preparing groove before welding can be avoided. The evolution law of the microstructure and GB characteristics of the K-TIG WMZ under different welding heat inputs were studied. The influencing mechanism of the microstructure and GB characteristics on the mechanical properties of the titanium alloy K-TIG WMZ were analyzed. 2 ExperimentalFor the K-TIG welding tests, the BM was 12 mm-thick TC4 titanium alloy plate. The dimensions of the TC4 titanium alloy plate were 300 mm ×100 mm. The chemical composition of the TC4 titanium alloy is displayed in Table 1. Figure 1 shows the schematic diagram of the K-TIG welding system. A certain error occurred after the workpieces were cut or mechanically cleaned, so the gap between the two workpieces cannot be guaranteed to be 0 mm. In order to ensure the accuracy of the welding test, two workpieces were fixed with a gap of 0.5 mm before welding. Because TC4 titanium alloy has strong metal activity, it is easily contaminated by oil and other substances, and it oxidizes readily during welding. To obtain high-quality TC4 welds, the workpieces were cleaned with acetone, and the front and back of the workpieces were protected by high-purity argon (99.9%). At a welding speed of 3.5 mm/s, gas flow rate of 20 L/min and electrode gap of 2.0 mm, only the welding current was changed to carry out five sets of tests, referred to as No. 1 to No. 5. The specific welding parameters in the K-TIG experiments are shown in Table 2.Table 1 Chemical composition of TC4 titanium alloy (BM) plate (wt.%)Al V Fe C N O H Ti 6.11 4.06 0.12 0.012 0.012 0.156 0.0015 Bal.Fig. 1 Schematic diagram of K-TIG welding systemAfter K-TIG welding, the K-TIG weld geometry profiles were observed. The transverseShu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 418cross-sections of TC4 K-TIG welded joints wereetched by Keller reagent (2 mL HF+10 mL HNO3+88 mL H2O). According to the ASTM E709—08standard, X-ray nondestructive tests (NDTs) werecarried out to analyze the defects in the K-TIGwelds [13].Table 2Welding parameters in K-TIG weldingexperimentsTest No. Weldingcurrent/AWeldingspeed/(mm·s−1)Arcvoltage/VHeatinput/(kJ·mm−1)1 490 3.5 17.0 2.142 510 3.5 17.5 2.303 530 3.5 18.0 2.454 550 3.5 18.5 2.625 570 3.5 19.0 2.78The electron backscatter diffraction (EBSD) technique was applied to characterizing the grain boundary misorientation angle distribution (GBMAD) of the BM and WMZ under varying heat inputs. The specimens for the tensile property test, including the BM and WMZ, were prepared in accordance with the ASTM E8 standard [14]. The specimens for the Charpy impact test, including the BM and WMZ, were prepared in accordance with the ASTM A370 standard [15]. The specimen dimensions for tensile test and Charpy impact test are shown in Fig. 2. The morphologies of the Charpy impact fracture were observed by scanning electron microscopy (SEM).Fig. 2 Specimen dimensions for tensile test and Charpy impact test (unit: mm)3 Results and discussion3.1 Effect of heat input on K-TIG weldmorphologyFigure 3 shows the transverse cross-sections of the TC4 titanium alloy K-TIG welded joints under various heat input conditions. In Fig. 3(a), it can be seen that the K-TIG weld is not completely penetrated when the heat input is 2.14 kJ/mm. When the heat inputs are 2.30, 2.45 and 2.62 kJ/mm, the TC4 K-TIG welds are completely penetrated. The weld seam collapses, and the reinforcement on the back of the weld is too large when the heat input increases to 2.78 kJ/mm, as shown in Fig. 3(e). This is mainly because when the heat input is relativelyFig. 3Transverse cross-sections of K-TIG TC4 titanium alloy welded joint at various heat inputs: (a) 2.14 kJ/mm;(b) 2.30 kJ/mm; (c) 2.45 kJ/mm; (d) 2.62 kJ/mm; (e) 2.78 kJ/mmShu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 419 small, the penetration of the arc is insufficient. Thegas in the molten pool cannot escape from the keyhole in time, so the hole appears in the weld. However, when the heat input is too large, additional metal is melted, and the reinforcement on the back of the weld is too large, so the weld shape is poor. This proves that the K-TIG weld joints at heat inputs of 2.14 and 2.78 kJ/mm do not meet the welding requirements. Therefore, this study focused on the microstructure and mechanical properties of the WMZ when the welding heat inputs were between 2.30 and 2.62 kJ/mm.Figure 4 displays the profiles of the K-TIG welds at various heat inputs (2.30−2.62 kJ/mm). All of them were well formed, and the welds surfaces were bright and clear. When the heat inputs were 2.30−2.62 kJ/mm, X-ray nondestructive testing photos of the welds were taken. The welds in the picture were uniform, had a light black broadband, and did not have large white spots or lines, which indicated good welds. There were no defects, such as pores or cracks. Combining Fig. 3 and Fig. 4, it was proved that when TC4 titanium alloy plates were welded by using K-TIG welding, the welding process window was relatively small. Therefore, welding heat input is a key factor affecting the performance and morphology of welded joints.3.2 Microstructure of K-TIG WMZ at variousheat inputsThe EBSD technique was used to characterize the microstructure of the BM and WMZ at various heat inputs. Figures 5 and 6 display the phase maps and band contrast images, respectively. The blue phase represents αtitanium, and the yellow phase represents β titanium.Referring to Figs. 5 and 6, the microstructure of the BM was mainly composed of equiaxed αgrains, α laths and a few retained β grains. Through Fig. 3, it can be seen that the grains of the WMZ became coarser. Figures 6(b), (c) and (d) display the microstructures of Areas 1, 2 and 3 in Fig. 3, respectively. Compared with the microstructure of the BM, the microstructures of the WMZ at various heat inputs were mainly composed of αlaths that were relatively dispersed and distributed in multiple directions. This was mainly because the temperature of the WMZ reached the βtransus temperature (995 °C), the primary αgrains in the WMZ were completely transformed into β phase,Fig. 4Profiles of K-TIG welds at various heat inputs: (a) 2.30 kJ/mm; (b) 2.45 kJ/mm; (c) 2.62 kJ/mmand a large number of αlaths formed during the subsequent cooling process. Although the phases in the WMZ were the same at various heat inputs, their morphologies were different. When the heat input was 2.30 kJ/mm, α laths formed in the WMZ were relatively short. When the heat input increased, αlaths became long. AHMED and RACK [16] reported that the cooling rate during the α→βtransformation could directly determine the subsequent evolution of the microstructure. When the cooling rate was relatively fast, βphase was directly transformed into α′ phase, and residual βphase also existed around α′ phase [1]. It could beShu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425420Fig. 5 Microstructures of BM (a) and WMZ at heat inputs of 2.30 kJ/mm (b), 2.45 kJ/mm (c) and 2.62 kJ/mm (d)Fig. 6 Band contrast images of BM (a) and WMZ at heat inputs of 2.30 kJ/mm (b), 2.45 kJ/mm (c) and 2.62 kJ/mm (d)seen from Figs. 6(b −d) that rod-like or granular structures were distributed between α laths. Residual β phase also existed around these structures. Because the K-TIG welding speed was relatively fast and its cooling speed was also fast, it was determined that these rod-like or granular structures in the WMZ comprised α′ phase. When the heat input increased, the corresponding cooling rate decreased, and the time for the growth of α laths was sufficient enough. Therefore, when the heat input increased, α laths increased in length, and α′ phase and residual β phase were also reduced.Shu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 421The microstructures of WMZ under varying heat input conditions indicate that only α phase, α′ phase and residual βphase exist in the WMZ, and no other precipitated phases exist.3.3 GBMAD of WMZ at various heat inputsIn polycrystalline materials, the GBMAD has certain influence on the mechanical properties of materials, which was proven by PARK et al [17]. The GBMAD can be categorized as low-angle GB (2°≤θ≤10°) and high-angle GB (θ≥15°) in accordance with the orientation angles of the GB [18]. Figure 7 displays the GBMAD maps of αphase in the BM and WMZ at various heat inputs. The blue lines indicate high-angle GB, and the black lines indicate low-angle GB. Figure 8 shows the high-angle GB proportion of α phase in the BM and WMZ. In the BM, the proportion of high-angle GB was 48.1%. In the WMZ, the proportion of high-angle GB increased as the heat input increased; it was 78.9%, 81.4% and 87.2% when the heat input was 2.30, 2.45 and 2.62 kJ/mm, respectively. This was mainly caused by changes in αphase morphology. In the BM, αphase was mainly equiaxed. In the WMZ, αphase existed mainly in the form of laths. When the heat input increased, α laths became fine and long. Therefore, the proportion of high-angle GB in the WMZ increased as the heat input increased.In previous study [4], it was found that large- angle GB had certain effect on the impact toughness of welded joints. Under certain conditions, as the proportion of high-angle GB increased, the impact toughness of the material gradually increased. It was proved that the proportion of high-angle GB was the main basis for judging the impact toughness of WMZ. Therefore, it could be inferred that when the heat input increased from 2.30 to 2.62 kJ/mm, the impact toughness of the WMZ gradually increased.3.4 Mechanical properties3.4.1 Tensile propertiesThe tensile properties of the BM and WMZ at various heat inputs are shown in Fig. 9. Figure 9(a) shows the tensile curves of the BM and WMZ at various heat inputs, and Fig. 9(b) displays the yield strength and elongation of the BM and WMZ at various heat inputs. The yield strength and elongation of the BM were 1054.5 MPa and 18.3%, respectively. When the heat inputs were 2.30, 2.45 and 2.62 kJ/mm, the tensile strengths of the K-TIGFig. 7GBMAD maps of αphase in BM (a) and WMZ at heat inputs of 2.30 kJ/mm (b), 2.45 kJ/mm (c) and 2.62 kJ/mm (d)Shu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 422Fig. 8 High-angle GB (HAGB) proportion of α phase in BM and WMZFig. 9Engineering stress−engineering strain curves (a), yield strength and elongation (b) of BM and WMZ at various heat inputsWMZ were 1089.8, 1072.1 and 1013.5 MPa, respectively; the elongations of the K-TIG WMZ were 3.5%, 8.3% and 11.8%, respectively. The experimental results showed that when the heat inputs increased from 2.30 to 2.62 kJ/mm, the tensile strengths of the TC4 titanium alloy K-TIG WMZ gradually decreased. When the heat input was 2.62 kJ/mm, the tensile strength of the WMZ was lower than that of the BM, but the tensile strength requirement (greater than 895 MPa) of the TC4 titanium alloy plate in the ASTM B256—05 standard was reached [19]. The elongation of the TC4 titanium alloy K-TIG WMZ at various heat inputs was lower than that of the BM. When the heat input increased, the elongation of the WMZ gradually increased. This was mainly because α′ phase could increase the strength of the material. When the heat input increased, the corresponding cooling rate decreased, and the growth time for the αlaths was sufficient enough. The α′phase decreased with increasing heat input, so the tensile strength of WMZ decreased and the elongation of the WMZ increased. By comparing the tensile strength and elongation of the K-TIG WMZ at various heat inputs, it was indicated that the microstructure of the WMZ had a certain effect on its tensile properties. Under certain conditions, the tensile properties of the TC4 titanium alloy K-TIG WMZ could be improved by changing the heat input.3.4.2 Charpy impact propertiesThe energies absorbed by the BM and WMZ during the Charpy impact tests are shown in Table 3. When the heat inputs were 2.30, 2.45 and 2.62 kJ/mm, the average values of the energy absorbed in the WMZ were 20.4, 32.1 and 33.6 J, respectively. The average value of the energy absorbed in the BM was 24.3 J. The Charpy impact test results showed that with increasing heat input, the energy absorbed in the WMZ gradually increased. When the heat inputs were 2.45 and 2.62 kJ/mm, the average value of the energy absorbed by the WMZ was larger than that of the BM. When the heat input was 2.30 kJ/mm, theTable 3Charpy impact absorbed energy in different zones of specimenZoneHeat input/(kJ·mm−1)Absorbed energy/JNo. 1 No. 2 No. 3 Average value BM −23.5 24.2 25.1 24.3 WMZ 2.30 19.9 19.8 21.4 20.4 WMZ 2.45 30.1 33.5 32.7 32.1 WMZ 2.62 33.7 33.7 33.4 33.6Shu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 423average value of the energy absorbed by the WMZ was slightly lower than that of the BM. However, it reached 84% of the BM.The fracture micrograph of the BM is displayed in Fig. 10(a). The fracture micrographs of the WMZ at various heat inputs are shown in Figs. 10(b−d). It can be seen that there were tear edges and dimples in the BM and WMZ. Therefore, it can be determined that the BM and WMZ plastically deformed before fracture occurred, and the fracture mode of the WMZ was ductile fracture. It can be seen in Figs. 10(b−d) that when the heat input gradually increased, the dimple size in the impact fracture of the WMZ gradually increased. When the welding heat input increased from 2.30 to 2.62 kJ/mm, the energy absorbed by the WMZ increased during the impact fracture process, which was consistent with the Charpy impact test results. The impact absorbed energy of materials is an important index used to evaluate the anti- destructive ability of metal materials. When other parameters were constant, the greater the value of the impact absorbed energy of the material was, the stronger the impact resistance was and the better the impact toughness was. According to the Charpy impact test results, as the heat input increased, the impact toughness of the K-TIG WMZ also increased.WRONSKI et al [20] pointed out that high- angle GB could effectively prevent the propagation of brittle crack. Therefore, the higher the proportion of high-angle GB was, the greater the energy absorbed during the fracture process was, and the better the impact toughness was. In Fig. 8, it could be seen that when the heat input was 2.30 kJ/mm, the high-angle GB proportion in the WMZ was greater than that in the BM, while the impact toughness of the WMZ is lower than that of the BM. Therefore, it could be seen that the proportion of high-angle GB was not the only factor affecting the impact toughness. THOMAS et al [21] reported that α′phase had a certain impact on the impact toughness of WMZ. When α′ phase appeared in the WMZ, the impact toughness of the WMZ was less than that of the BM. When α′ phase was eliminated, the impact toughness of the WMZ was improved. InFig. 10SEM images of Charpy impact fracture surfaces: (a) BM; (b−d) WMZ at heat inputs of 2.30 kJ/mm (b), 2.45 kJ/mm (c) and 2.62 kJ/mm (d)Shu-wan CUI, et al/Trans. Nonferrous Met. Soc. China 31(2021) 416−425 424Fig. 6, it could be seen that when the heat inputs were 2.30, 2.45 and 2.62 kJ/mm, α′ phase appeared in the WMZ. When the heat input was 2.30 kJ/mm, the impact toughness of the WMZ was lower than that of the BM. When the heat inputs were 2.62 and 2.45 kJ/mm, the impact toughness of the WMZ was higher than that of the BM. Therefore, α′ phase was not the only factor affecting the impact toughness of the WMZ. According to the above analysis, it could be seen that the impact toughness of the WMZ could be affected by the proportion of high-angle GB and presence of α′ phase.4 Conclusions(1) During the K-TIG welding process, 12 mm-thick TC4 titanium alloy plates were welded with varying heat inputs (2.30−2.62 kJ/mm).(2) When the heat input gradually increased, αlaths in the WMZ became fine and long, and α′phase and residual β phase were also reduced. The proportion of high-angle GBs in the WMZ also increased as the heat input increased.(3) When the heat input was in the range of 2.30−2.62 kJ/mm, the K-TIG TC4 titanium alloy welds were well formed. The tensile strength and impact energy absorbed by the WMZ were in accordance with the welding requirements.(4) The α′phase decreased with increasing heat input, so the tensile strength of WMZ decreased and the elongation of the WMZ increased. The impact toughness of the WMZ can be affected by the proportion of high-angle GB and the presence of α′ phase. AcknowledgmentsThe authors are grateful for the financial supports from the Key Research and Development Program of Guangdong Province, China (2020B090928003), the Natural Science Foundation of Guangdong Province, China (2020A1515011050), the Science and Technology Base and Talent Special Project of Guangxi Province, China (AD19245150) and Guangxi University of Science and Technology Doctoral Fund, China (19Z27).References[1]PENG He-li, LI Xi-feng, CHEN Xu, JIANG Jun, LUOJing-feng, XIONG Wei, CHEN Jun. Effect of grain size on high-temperature stress relaxation behavior of fine-grained TC4 titanium alloy [J]. Transactions of Nonferrous Metals Society of China, 2020, 30(3): 668−677.[2]YIN Mei-gui, CAI Zhen-bin, LI Zhen-yang, ZHOUZhong-rong, WANG Wen-jian, HE Wei-feng. Improving impact wear resistance of Ti−6Al−4V alloy treated by laser shock peening [J]. 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Journal of Materials Science, 1993, 28(18): 4892−4899.TC4钛合金K-TIG焊接接头的显微组织及力学性能崔书婉1,2，石永华2，张程士31. 广西科技大学机械与交通工程学院，柳州545006；2. 华南理工大学机械与汽车工程学院，广州510640；3. 柳州上汽汽车变速器有限公司，柳州545006摘要：采用锁孔型钨极氩弧焊(K-TIG)在不同热量输入条件下焊接厚度为12 mm的Ti−6Al−4V(TC4)钛合金板，并研究焊缝金属区(WMZ)的显微组织、晶界特征及力学性能。

TC4钛合金摩擦焊接头的力学性能及显微组织

TC4钛合金摩擦焊接头的力学性能及显微组织刘小文1,　史永高2,　毛信孚1,　杜随更1(1.西北工业大学,西安　710072;2.西安工学院,西安　710032)摘　要:　对钛合金T C4(T i-6Al-4V)摩擦焊接性能进行了较详细的试验分析。

结合摩擦焊接参数的优化选择,叙述了该合金摩擦焊接过程的特点,讨论分析了其焊接接头的力学性能及焊合区的显微组织结构。

试验结果表明,该合金具有良好的摩擦焊接性,在无特殊保护措施的条件下,优化工艺,可获得良好的焊接接头。

由于T C4钛合金导热系数小,热塑性高,容易氧化,摩擦焊亦选用较小的规范参数。

焊合区硬度略低于母材,拉伸试样断于母材,拉伸、冲击断口均表现出明显的韧性断裂特征。

力学性能数据表明,用优化的规范参数,T C4钛合金可获得等强、等韧甚至超强、超韧于母材的摩擦焊接接头。

T C4钛合金摩擦焊接接头焊合区组织为细密的网蓝状组织,焊合区与母材过渡区为双态组织。

关键词:　钛合金摩擦焊接;力学性能;显微组织中图分类号:TG404 文献标识码:A 文章编号:0253-360X(2001)06-77-04刘小文0　序言T C4属于典型的α+β两相钛合金。

由于其具有较高的比强度,在航空工业常用于制造航空发动机压气机叶片、盘及某些紧固件等。

在其它工业部门也有广泛的用途,其部件的品种、形状、结构繁多。

据报道,对于钛合金结构所用的焊接方法有氩弧焊、等离子弧焊、电子束焊、点焊、钎焊以及真空扩散焊[1]。

目前国内还未见到有介绍钛合金摩擦焊接的报道。

近年来,随着新材料、新结构的发展,摩擦焊接技术的优越性亦显得更加明显。

本文探讨了T C4钛合金摩擦焊接过程的特点,优化了摩擦焊接规范参数,讨论和分析了焊合区显微组织结构及力学性能,为进一步扩大摩擦焊接技术在钛合金结构中的应用提供了一定的理论和实践依据。

1　试验材料与设备本试验所用材料为<28mm的T C4钛合金棒料。

其化学成分如表1所示,力学性能如表2所示。

TC4钛合金焊接接头组织不均匀性与疲劳性能-Engineering

[ 2- 4] [ 1]
方法 ( 多晶局域梯度模型) 和大量的低周疲劳实验, 综合考察 T C4 钛合金的微观组织不均匀性与疲劳性能的对应关系 , 通过研究结果力求建立电子束焊接工艺宏观力学性能与微观结构之间关系的桥梁 , 为深入研究电子束焊接工艺评定方法提供理论和实验基础规范。 1 实验材料钛合金样品采用 T C4 热轧板材 , 板厚为 20mm, 经检测其化学成分如表 1 所示。焊接方法采用电子束焊接 , 焊接试样尺寸为 200mm 650 180m m 20mm, 焊缝垂直于轧向 , 位于试样中间 , 焊后热处理为 , 保温 4h 。各试样的具体焊接工艺参数如表 2 所示。
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材料工程 / 2010 年 1 期
TC4 钛合金焊接接头组织不均匀性与疲劳性能
M icrostructure H eterogenicit y and Fatigue Property of Weld Joints of T C 4 T itanium A lloy
李清华 1 , 胡树兵 1 , 李行志1 , 肖建中1 , 王亚军2 , 刘昕2 , 籍龙波1
Fig. 1 图1 显微组织不均匀性表征参数 Parameters ex pres sion of micros tru ct ure het erogenicit y
为说明 T C4 钛合金显微组织不均匀性和疲劳性能之间的关系, 本工作设计了一种光滑疲劳试样 ( 图 2) , 其中试样宽度 16mm, 去除焊缝余高和上下部各 2mm , 以去除几何应力集中和熔合线气孔等疲劳裂纹萌生因素 , 更好反映显微组织不均匀性和疲劳性能之间的关系。用 SH IMADZU EA 10 型电液伺服疲劳试验机进行低周疲劳实验, 疲劳实验频率为 10H z, 正弦波 , 应力比 0. 1, 应力水平 0. 6 b 。 3 实验结果与分析

TC4 钛合金与YG8硬质合金高频感应钎焊组织及性能研究

TC4 钛合金与YG8硬质合金高频感应钎焊组织及性能研究邵长斌;熊江涛;孙福;张赋升;李京龙【摘要】在钎焊温度920～970℃和钎焊保温时间20s条件下,采用B Cu64MnNi 钎料对TC4钛合金与YG8硬质合金进行真空高频感应钎焊实验.利用扫描电镜(SEM)、能谱分析(EDS)及X射线衍射分析(XRD)对钎焊接头的显微组织、成分分布和相结构进行了研究,测试了接头的抗拉强度并观察分析了断口形貌及其元素分布.结果表明,钎焊温度为920～940℃时TC4与YG8钎焊接头显微结构为:TC4/β Ti/TiCu+ Ti3 Cu4+ TiMn+ Cu(Mn,Ni)/YG8,钎缝呈镶嵌结构;随钎焊温度升高,脆性片状组织TiMn增多,镶嵌结构破坏,接头性能明显降低;钎焊温度为930℃时,获得的接头抗拉强度最高,为206MPa.【期刊名称】《材料工程》【年(卷),期】2014(000)009【总页数】6页(P26-31)【关键词】高频感应钎焊;YG8;TC4;显微组织【作者】邵长斌;熊江涛;孙福;张赋升;李京龙【作者单位】西北工业大学凝固技术国家重点实验室,西安710072;西北工业大学摩擦焊接陕西省重点实验室,西安710072;西北工业大学摩擦焊接陕西省重点实验室,西安710072;西北工业大学摩擦焊接陕西省重点实验室,西安710072;西北工业大学摩擦焊接陕西省重点实验室,西安710072;西北工业大学摩擦焊接陕西省重点实验室,西安710072【正文语种】中文【中图分类】TG454TC4是一种广泛应用于航空、航天的钛合金材料，具有优异的综合性能；然而由于TC4易塑性变形、加工硬化趋向较低及表面氧化膜易去除等因素，使其耐磨性能较差［1－3］。

WC－Co类硬质合金具有强度高、高温硬度高、耐磨损等特点，因此将钛合金与硬质合金可靠连接可以增加TC4的表面耐磨性，延长其在超声波焊头等磨损工况下的使用寿命［4－6］。

非晶钎料真空钎焊tc4钛合金及不锈钢的研究

摘要钛合金具有强度高、耐蚀性好及高温机械性能优良等优点，能够广泛地适用于航空、航天、军事等特殊和重要的工业领域。

但是钛合金可加工性能差，并且价格较贵，寻求钛合金可靠的连接方法至关重要。

Ti-6Al-4V，是钛合金中使用最多的合金之一。

不锈钢是一种常用的工业和生活材料，具有许多优异的性能，应用十分广泛，且成本相对较低，然而钢铁的耐蚀性比较差，并且钢铁的比重较大。

因而在某些情况下需要将钢与钛连接起来应用，才能充分发挥各自的优点。

钛合金和钢焊接时接头易产生金属间化合物(Ti2Fe、TiFe、TiFe2等)，焊接后接头内应力很大，造成接头性能较差。

探索更为科学、高效的TC4钛合金和不锈钢焊接方法和焊接工艺，获得性能较好的接头，意义重大。

钛合金和不锈钢的主要焊接方法为真空钎焊。

真空钎焊具有焊接温度较低、钎焊试样不易受杂质气体污染、焊接变形小、残余应力小等特点。

非晶钎料是一种新型的钎料，具有熔点低、焊接性能好，焊接方便等一系列的优点，故选择非晶钎料代替传统的晶态钎料进行真空钎焊。

钛基非晶钎料作为真空钎焊TC4钛合金的重要非晶钎料，具有易于和母材产生相互扩散、成本较低等特有的优点。

本实验采用传统的钛基非晶钎料Ti37.5Zr37.5Ni10Cu15真空钎焊不锈钢和TC4钛合金。

另外通过在钎料Ti37.5Zr37.5Ni10Cu15添加一定量的合金元素Sn，制备出新的钛基非晶钎料Ti33.75Zr33.75Ni10Cu15Sn7.5和Ti32.5Zr32.5Ni10Cu15Sn10，在钎焊TC4与TC4时希望能够降低钎料的熔点，提高可焊性，并保证钎焊接头的力学性能。

对钎料进行XRD测试可以确定三种钎料均为非晶态，对钎料进行DSC测试能够得到钎料的熔点，并且发现Ti32.5Zr32.5Ni10Cu15Sn10非晶钎料的熔点有所降低。

在保温时间为10 min下，选取若干个不同的钎焊温度进行钎焊实验。

对钎焊试样进行显微组织观察和机械性能测试。

TC4钛合金窄间隙焊接接头组织特性及氢脆敏感性

TC4钛合金窄间隙焊接接头组织特性及氢脆敏感性TC4钛合金是一种广泛应用于航空航天和化工领域的材料，其具有良好的机械性能和耐腐蚀性。

然而，在焊接过程中会产生窄间隙焊接接头，而该接头的组织特性及氢脆敏感性对焊接接头的性能和可靠性有着重要影响。

首先，我们来探讨TC4钛合金窄间隙焊接接头的组织特性。

在窄间隙焊接过程中，由于焊接热源的局部加热和快速冷却，接头区域的组织结构会发生变化。

一般来说，TC4钛合金的组织结构主要包括α相（钛固溶体）和β相（钛合金化合物）。

在窄间隙焊接接头中，由于焊接热影响区的温度变化较大，会导致α相和β相的重分布和再结晶现象发生。

这些变化会导致接头处的组织结构发生变化，可能会影响接头的力学性能和耐腐蚀性。

其次，我们来探讨TC4钛合金窄间隙焊接接头的氢脆敏感性。

氢脆是指金属在存在氢气的环境下容易发生脆性断裂的现象。

在焊接过程中，由于焊接材料和焊接剂中可能存在的水分和氢气，TC4钛合金窄间隙焊接接头容易受到氢脆的影响。

氢的存在会导致钛合金的晶界处形成氢化物，从而降低接头的韧性和强度。

因此，控制氢气的存在和适当的热处理方法对于提高接头的抗氢脆性至关重要。

为了研究TC4钛合金窄间隙焊接接头的组织特性和氢脆敏感性，许多学者进行了大量的研究工作。

他们通过金相显微镜、扫描电子显微镜等多种方法对接头的组织结构进行观察和分析，并通过氢脆实验和力学性能测试来评估接头的氢脆敏感性。

他们发现，窄间隙焊接接头的组织结构与焊接参数、焊接材料和焊接剂等因素密切相关。

同时，适当的热处理方法（如热处理和固溶处理）可以减少接头的氢脆敏感性，并提高接头的力学性能。

综上所述，TC4钛合金窄间隙焊接接头的组织特性和氢脆敏感性对于接头的性能和可靠性具有重要影响。

通过研究和优化焊接工艺参数、材料选择和热处理方法等方面，可以提高窄间隙焊接接头的组织结构和抗氢脆性，从而提高接头的性能和可靠性。

这对于航空航天和化工等领域中对焊接接头要求较高的应用具有重要意义综合上述研究，可以得出TC4钛合金窄间隙焊接接头的组织特性和氢脆敏感性对接头的性能和可靠性具有重要影响的结论。

激光焊接TC4钛合金组织性能研究_董智军

27激光焊接TC4钛合金组织性能研究董智军1, 2吕涛1雷正龙1陈彦宾1李俐群1周恺3马瑞3（1.哈尔滨工业大学先进焊接与连接国家重点实验室，哈尔滨 150001； 2.上海航天精密机械研究所，上海 201600；3. 北京动力机械研究所，北京 100074）摘要：研究激光焊接对TC4钛合金焊缝成形和力学性能的影响，并利用OM 、XRD 和TEM 等手段对焊接接头的显微组织特征进行了分析。

结果表明，激光焊接TC4钛合金成形较好，但在焊缝熔合线附近容易产生圆形气孔。

焊缝由单一的α′马氏体构成，并呈网篮状分布。

热影响区组织为α′马氏体和初始α相。

焊缝和热影响区的显微硬度明显高于母材，而焊缝的硬度最高且硬度分布平缓。

TC4钛合金焊接接头的室温平均抗拉强度为1126MPa ，与母材的抗拉强度相当，延伸率为11.12%，比母材略低，焊接接头均断在母材区域。

关键词：钛合金；激光焊接；微观组织；显微硬度；抗拉强度Microstructure and Mechanical Properties of Laser Welded TC4 AlloysDong Zhijun 1, 2 LvTao 1 Lei Zhenglong 1 Chen Yanbin 1 Li Liqun 1 Zhou Kai 3 Ma Rui 3 (1.State Key Laboratory of Advanced Welding and Joining, Harbin 150001; 2. Shanghai Spaceflight Precision Mechanism Institute, Shanghai 201600;3. Beijing Power Machinery Research Institute, Beijing 100074)Abstract ：The effect of laser welding on the weld appearance and mechanical properties of TC4 (Ti-6Al-4V)alloys were discussed, and the microstructure characterization of the joints was investigated by means of OM, XRD and TEM. The experimental results showed that a good weld appearance could be obtained; however, some round blowholes emerged easliy near the weld fusion line. The weld seam is only composed of α’ martensite which takes on basket weave structure. And the microstructure of heat affected zone is constituted of α’ martensite and the initial α phase. The microhardness of the weld seam and heat affected zone is higher than that of the base metal. And the weld seam exhibits the highest values in the welded joint. The tensile strength of the laser welded joints is 1126 MPa at room temperature, which is equal to that of the base metal. The elongation of the joint, however, is slightly lower than the base metal with a ductility of 11.12%. The welded joints of TC4 alloys are all broken on the area of the base metal.Key words ：Ti alloy ；laser welding ；microstructure ；microhardness ；tensile strength 1 引言钛合金由于具有比强度高、抗腐蚀性能好，以及良好的耐热性和焊接性等优点，在航天、航空、核工业、舰船等国防和民用领域得到广泛应用[1～3]。

TC4钛合金线性摩擦焊接头组织及残余应力分布特征

TC4钛合金线性摩擦焊接头组织及残余应力分布特征张杰;张田仓;陆业航;张庆云;李菊【摘要】Using microscopy and X ray dif-fraction technology, a detailed investigation on the micro-structural and residual stress distribution in linear friction welded Ti–6Al–4V is performed. The results show that, during welding process, the equiaxedαand transformedβin thermo-mechanically affected zone is elongated and broken, and the microstructure in welded zone is ultra-ifne grain. Residual stress distribution of the joint only has tensile stress zone in one side, compared with the other side which contains both tensile stress zone and compress stress zone. In the transverse section of welding line, re-sidual stress in transverse direction presents V and W type distribution patterns at the center of welding line and at both ends of welding line respectively. While, in the lon-gitudinal section of welding line, high tensile stress in the central part is the distribution characteristic of longitudinal direction of residual stress, changing to compress stress near both ends of welding line gradually.%使用光学显微镜和X射线衍射法对TC4钛合金线性摩擦焊接头组织和残余应力分布特征进行研究。

TC4真空电子束焊后热处理对接头组织性能影响

TC4真空电子束焊后热处理对接头组织性能影响作者：李常青陈友富来源：《中国军转民》 2015年第7期采用真空电子束焊接不等厚TC4 钛环，焊后对接头进行整体退火、电子束局部退火、不退火方式获得3 个接头。

采用X 射线测残余应力、通过拉伸、弯曲试验以及光学显微镜对焊接接头组织和性能进行研究。

结果表明：焊后局部退火与整体退火能降低接头残余应力且使接头区域残余应力变化稳定，其作用效果相当；真空电子束局部退火能细化焊缝针状组织，改善热影响区组织。

三种状态下接头都具有较高的抗拉强度并表现出良好的弯曲性能。

在无法进行整体退火热处理的情况下，真空电子束局部退火可以替代整体退火。

李常青陈友富TC4（Ti-6Al-4V）钛合金，属于α+β 双相钛合金，由于其具有较好的综合力学性能，并可热处理强化，在航空航天、化工、汽车制造和精密加工工业得到了广泛的应用。

真空电子束焊接非常适用于TC4钛合金的焊接，因为其具有加热功率密度大，焊接速度快，焊接冶金质量好、焊缝窄、焊缝角变形小、焊缝及热影响区晶粒细小，焊缝和热影响区不会被空气污染等优点。

电子束局部热处理是电子束以线或面的形式，对焊缝及其附近局部区域进行散焦扫描加热处理。

在真空电子束焊后立即进行电子束局部热处理，能在不影响构件整体性能的同时提高效率、节省能源。

对于钛合金，大型结构复杂的构件，电子束局部热处理是一种较为理想的焊后热处理方法。

本文通过对TC4 钛环进行真空电子束焊及焊后真空电子束局部退火的工艺研究，分析了真空电子束局部热处理对TC4 钛环焊接接头组织和性能的影响。

旨在为钛合金真空电子束焊后局部退火提供具有实际应用价值的数据。

1. 试验材料和方法试验所用TC4 钛环结构及接头形式如图1、图2 所示。

3 对钛环，分别打上编号1#、2#、3#。

母材化学成分见表1，组织见图3，组织为等轴（α+β）组织。

试验用LARA52真空电子束焊机，通过自制工装将试圈装配到电子束焊机工作平台，表2为焊接工艺参数。

不同热处理工艺下TC4-DT钛合金的显微组织及力学性能

图１实验用Ｔ４ＤＣ一Ｔ钛合金显微组织
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采用箱式电阻炉（温精度为 ±３ｏ，分别对控Ｃ）Ｔ４ＤＣ－Ｔ钛合金进行如下制度的热处理。（）相区１两固溶＋时效：两相区９０ｏ／／Ｃ５３Ｃ１ｈＡ、９５℃／／１ｈＡ、９０℃／／Ｃ热处理，然后进行５０ｏ／／Ｃ７１ｈＡ５６ｈＣ
１１０℃开坯锻造，并在两相温区（５经两次锻５９０ｏＣ）
ＴＣ２１６＿Ｊ
、
Ｔ４Ｄ等。将该类合金Ｃ一Ｔ
在两相区固溶加时效处理得到等轴或双态组织，可
以获得高强度、高塑性以及优异的抗疲劳强度，但
用淬火金相法测得Ｏ＋￣／转变温度为９９℃ 。／／，３３７
形成连续平直的晶界Ｏ网络，使材料的塑性显著降／低，对区固溶工艺参数的要求苛刻。通过卢区固
溶后时效处理获得片层组织，在提高损伤容限性能的同时，往往会损失塑性，即强度．性一塑韧性的匹配
第２９卷第１期
２２，０１正
２月
Ｔｉ嚣
Ｆ１ｙ２１Ｖｕ０ｅ２ｏｂｒ１０９．ｒＮ．ａ
不同热处理工艺下Ｔ４一ＤＣＴ钛合金的显微组织及力学性能

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TC4钛合金真空钎焊接头显微组织分析
摘要：采用ag-cu-ti钎料对tc4钛合金进行真空钎焊；采用金相分析、扫描电镜对钎缝的组织结构、元素分布情况进行分析，并对焊件的整体力学性能进行拉伸测试。

结果表明，tc4合金板真空钎焊搭接接头处抗剪强度在200mpa以上，钎焊接头处总体的力学性能优于母材；钎缝与基体相临的部位析出了弥散相，钎缝处有cu 的固溶体析出；焊接接头中的主要元素ti、al、v、ag、cu呈规律性分布，钎缝及扩散区域得到以细小笋状的方式生长的cu基固溶体，是为ag-cu共晶组织。

abstract： vacuum brazing of tc4 was carried out with ag-cu -ti filler metal. organizational structure， element distribution of brazed joints were investigated by means of scanning electron microscopy and metallographic microscope，and the joint whole mechanical property was determined by tensile testing method. the results show that shear strength for the brazing joint of tc4 titanium alloy is above 200mpa and whole mechanical property of the brazing joint are better than base metal. dispersed network phase form between base metal and brazing seam， and cu-based solid solution separate out in the brazing seam. ti， al， v， ag and cu of the brazing joint were regular distribution. ag-cu eutectic structure of brazing seam and diffuse region were grown by slender and
small bamboo shoots mode.
关键词： ag-cu-ti；真空钎焊；显微组织
key words： ag-cu-ti；vacuum brazing；microstructure
中图分类号：p755.1 文献标识码：a 文章编号：1006-4311（2013）22-0048-03
0 引言
tc4合金中钛的含量很高，钛是活性很强的金属材料，在高温下容易与n2、h2、o2反应，并同其它许多金属反应生成脆性金属间化合物，在600℃氧与钛发生强烈反应，800℃氧化膜开始向钛中溶解扩散，氮与钛在高温下则形成脆硬的氮化钛，对钛的塑性影响较大，氢的存在则由于γ（tih2）相析出，也同样使其塑性、韧性降低[1]。

采用真空钎焊选择合适的钎料，可以避免高温情况下，氧、氮、氢各种气体元素对tc4合金钎缝性能的影响，从而提高接头的力学性能[1]。

在钛及钛合金的焊接中，钎焊适于焊接受载不大或在常温下工作的接头，对于精密的、微型复杂的及多钎缝的焊件尤其适用[2]。

在一些钛合金复杂结构、薄壁精密结构的制造工艺中，由于钎焊连接具有独特的优势而愈来愈受到重视，对钛合金用钎料的研究也逐渐成为钎焊领域研究的热点之一[3]。

由此，了解tc4
钛合金真空钎焊接头微观组织结构及元素分布情况是十分必要的。

1 试验材料及方法
1.1 试验材料试验母材采用厚度为1mm的tc4钛合学成分见表1。

要得到组织和性能满意的钎焊接头，钎料必须能较好地润湿母材并能填满接头间隙。

此外，钎料的焊接温度必须低于tc4的相变温度，否则将引起母材β晶粒长大，从而影响材料的性能。

试验用钎料采用 ag基ag-cu系钎料ag-cu-ti，其熔化温度为779～820℃。

1.2 试验方法目前的钎焊技术和钎料所形成的焊件的性能与其原始基体金属的性能水平相差不多。

钛合金的本质决定了其钎焊的主要温度和时间局限性。

总的来说，使用焊料并在钎焊温度低于β相转变温度时可获得优良机械性能的钛钎焊部件。

接头形式：本试验所用的材料为1mm的tc4板材；搭接接头。

接头形式见图1。

薄件为装配方便，搭边长度l=（4～5）δ；δ——待焊工件厚度[4]。

由此得l=4δ=4mm。

接头的装配间隙大小是影响钎焊焊缝致密性和接头强度的关键
因素之一。

熔态钎料在钎缝中作直线流动，钎缝的毛细能力起很大作用，毛细能力又与钎缝的类型和钎缝间隙的大小有关系。

一般说来，钎缝间隙小比间隙大的钎缝的直线流动性更好，但也不是越小越好，钎缝间隙的最佳值在0.01～0.2mm之间，具体数值视母材的种类而定[5]。

在不影响钎料填充的前提下，钎焊间隙越小越好[6]。

此次试验银基钎料，钛合金焊接装配间隙取为0.05mm。

在钎焊温度下，一方面要使钎料熔化，在毛细管作用下填满接头间隙，并与基体金属进行合金化作用；另一方面使基体材料完成热处理程序中的某一步骤（固溶或淬火）[6]。

真空钎焊设备为“真空扩散焊机-6”；其最高加热温度为1650℃，压力为15ton，真空
度为1×10-5torr，钎焊工艺参数如表2。

焊接完成后，对钎焊试样进行拉伸试验；并对接头进行显微金相分析，同时用扫描电镜对钎焊界面的元素分布及组织结构进行分析。

2 试验结果及分析
2.1 拉伸试验分析在“cmt5
3.5微机控制电子万能试验机”上拉伸实验，四组钎接试样均从搭接接头（焊缝）边缘并靠近接头处断裂，如图2，这说明焊接接头处所能承受的最大拉力大于母材，按照此拉力核算，搭接接头处抗剪强度应在200mpa以上，由此可知，钎焊焊件的接头处总体的力学性能要优于母材，焊件总的力学性能较好，焊接情况优良。

2.2 金相分析对钎焊试件外观检查发现其变形很小，装配较好，焊接情况良好。

钎焊接头的金相试样经kroll 侵蚀剂
（2mlhf+5mlhno3+93mlh2o）进行侵蚀后，用xjp-2b型台式金相显微镜对钎焊接头进行金相观察，图3为钎焊焊缝100倍照片，从照片中可以看出，焊缝较均匀，没有出现污染变质等不良现象。

钎焊比较适合对钛合金进行焊接，就是由于钎料易于与钛合金基体合金化，但是这种合金化容易使焊缝变的硬而脆，使材料塑性和强度降低。

但是由图4不难看出，基体为细小α+β双相等轴晶体，钎焊缝中心浅灰色的为共晶的钎料组织，钎焊缝两侧是钎料向母材扩散形成的扩散层，在与基体相临的部位由于析出了弥散相，故易受腐蚀而呈深色。

从图中可以看出在钎焊焊缝处的钎料均以笋状的方式生长，较细小，这是由于有细小针状cu的固溶体析出；在焊缝中间处可能出现了ag-cu共晶；但没有发现明显的金属化合物，从而没有因为出现金属化合物而使接头处的塑性、韧性降低。

2.3 扫描电镜分析为了进一步对真空钎焊接头处的组织结构及元素分布情况进行研究，对真空钎焊接头用“camscan mx2600fe型热场发射扫描电子显微镜”进行扫描，并对部分区域及点进行能谱分析。

由图5可知元素分布具有较强的规律，母材和钎缝之间元素进行了扩散；如图6，笋状区域即为钎料生长扩散区域；但由于焊接保温时间较短（仅10min），钎料和母材之间的元素扩散不完全；结合图5和图6可以看出，在钎缝及钎料笋状生长扩散区域处ag、cu的谱线均成锯齿状，且ag的峰值对应cu的低谷，由此可知此区域形成了典型的ag-cu共晶组织，其灰黑色组织为cu基固溶体，白色相为ag基固溶体。

图7是在钎料生长扩散区域内的笋状钎料上所打的能谱，由（b）可以看出，cu的衍射强度较高，在此区域中cu形成的固溶体成细小的笋状，因为在这些元素中ag的原子序数最高，所以这个区域中可能有cu基固溶体中析出的富ag相，这需经过多次实验才能验证。

3 结论
①tc4合金板真空钎焊接头处所能承受的最大拉力大于基体，搭接接头处抗剪强度在200mpa以上，焊件接头处总体的力学性能优于母材，焊件总的力学性能较好。

②钎缝与基体相临的部位析出了弥散相，易受腐蚀；在钎焊焊缝处有cu的固溶体析出，均以笋状的方式生长并较细小，但没有发现明显的金属化合物。

③焊接接头中的主要元素ti、al、v、ag、cu呈规律性分布，钎缝及扩散区域得到ag基固溶体及以细小笋状的方式生长的cu基固溶体，是为ag-cu共晶组织。

④钎料生长扩散区域内的笋状钎料上的cu基固溶体中可能析出富ag相，这需后续多次实验才能验证。

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