SiC_w_6061Al复合材料无钎剂加压钎焊.pdf

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1、SiCw/6061Al复合材料无钎剂加压钎焊吕世雄1,于治水2,许志武1,闫久春1,杨士勤1,吴 林1(1.哈尔滨工业大学 现代焊接生产技术国家重点实验室,哈尔滨 150001;2.华东船舶工业学院 焊接研究所,镇江 212003)摘 要:提出一种新的钎焊方法 无钎剂加压钎焊,采用Zn-Al钎料进行了SiCW/6061Al复合材料的焊接试验,研究了温度、压力两工艺参数对接头强度及微观组织的影响规律,并初步分析了辅助工艺 机械刮擦的作用。试验发现,温度和压力是至关重要的钎焊工艺参数,当温度在400450,压力为30 MPa时,接头拉伸破坏于钎缝处,强度达到263.3 MPa,为母材抗拉强度的85

2、%90%。采用扫描电镜分析断口,发现其形貌为小韧窝+准解理+SiC晶须,还存在被拉伸拔掉的SiC晶须残留的凹坑,这证明了SiC晶须在钎缝中的强化作用。X射线衍射相结构分析表明,断口是由-Al(Zn)固溶体基体上均匀分布着SiC晶须组成,这同时表明钎缝主要有-Al(Zn)基体+SiC晶须组成。关键词:铝基复合材料;钎焊;压力;微观结构中图分类号:TG454 文献标识码:A 文章编号:0253-360X(2001)04-73-04吕世雄0 序 言近十多年来,铝基复合材料的研究及应用取得了很大进展,由于该材料比一般铝合金具有更高的比刚度、比强度及更好的耐磨性,在航天航空及交通领域具有更好应用前景。但

3、是,铝基复合材料结构件的应用受到缺乏可靠、方便的连接方法的限制。熔化焊因本身高温熔化使铝基复合材料中的增强相与基体合金发生较强烈的界面反应,恶化母材性能,并因焊缝中增强相的偏聚进一步恶化接头性能1。在固相扩散焊中,必须施加较大压力使被焊表面的氧化膜破碎,固相扩散焊方能顺利进行。但仅依靠存在浓度梯度作为相互扩散动力,扩散时间较长,且在焊缝/母材界面处存在增强相偏聚现象,使接头抗拉强度不尽人意2。在钎焊方法中,使用低熔点Al-Ge,Zn-Al钎料及较高熔点Al-Si钎料3。Al-Ge,Zn-Al钎料虽然使钎料温度低于450,但由于钎缝中较多Al-Ge,Zn-Al合金存在,其本身强度不高,而且在钎缝

4、/母材界面处也存在SiC晶须偏聚现象,而Al-Si钎料虽然本身强度较高,钎焊铝合金时强度也高,并与SiC晶须有较好的润湿性,但用Al-Si钎料钎焊SiCW/6061Al复合材料时,钎焊温度高,易使SiC晶须与合金发生反收稿日期:2001-04-02应,且也存在SiC晶须偏聚现象3。在瞬时液相扩散焊(TLP)中,采用了Cu,Ag,Ni,Al-Si,Al-Ge等中间层连接铝基复合材料4,5。在这些研究中,由于TLP方法焊接温度一般为500550,铝基复合材料已经软化了,所以只能采用较小的焊接压力,较长的保温时间使钎料熔化并与母材溶解、扩散、均匀化等过程实现连接,并要在真空或氩气保护下进行焊接。为此

5、,本文提出一种新的无钎剂加压钎焊方法连接SiCW/6061Al复合材料,时间短,不需要保护环境,研究了在钎焊过程中焊接温度、压力对接头性能及微观组织的影响规律,该结果将为提高此类材料的钎焊焊接质量奠定基础。1 试验材料及方法本文所用材料是经挤压铸造制备的SiCW/6061Al铝基复合材料,SiC晶须体积分数为20%,平均直径为0.5m,长度为30100m,抗拉强度为280310 MPa。试件加工成棒状,规格为10 mm40 mm,被焊表面需露出金属光泽。所用钎料成分如表1所示,其固-液相线温度为383.0399.4。在焊接之前,加热被焊工件使Zn-Al钎料熔化并铺展于工件表面上,机械刮擦液态Z

6、n-Al钎料/母 材界面,破碎母材表面氧化膜(通常为Al2O3),使第22卷 第4期2 0 0 1年8月焊接学报TRANSACTIONS OF THE CHINA WELDING INSTITUTIONVol.22No.4August2 0 0 1表1Zn-Al钎料的化学成分(质量分数,%)Table 1Chemical composition of Zn2Al filler metalElementsZnAlCuMgSiNiOthersContent89.34.23.220.82 0.8110.050.68液态Zn-Al钎料直接与母材中Al合金相互作用。一方面固态Al合金向液态钎料中溶解,一

7、方面液态钎料向固相Al合金中扩散、渗透。同时机械刮擦作用将会促使SiC晶须向钎料中过渡,并使其趋向均匀分布,使钎料成为含SiC晶须的复合材料,最后冷却。采用对焊接头,再对两试件的被焊表面进行二次加热,使钎料再次熔化,经搅拌、加压、保温、冷却后成为一个钎焊接头。第二次加热加压过程流程图如图1所示。图1 二次加热加压过程示意图Fig.1Illustration of procedure of secondaryheating and pressing1-heating,2-stirring,3-pressing and ejecting unwantedZn2Al solder,4-curing

8、micro2shrinkage voids andreducing stress concentration本文采用Instron-1186型电子万能拉伸机对钎焊接头进行了常温拉伸试验,拉伸速度0.5 mm/min;利用S-570扫描电子显微镜进行微观组织及断口分析;选用飞利浦X Pert Pw 3040型X衍射仪进行断口相结构的分析。2 讨论与分析2.1 钎焊温度当钎焊温度刚达到钎料的熔化温度时,钎料的流动性还未达到最佳状态,而且液态钎料向固态母材中的扩散系数及母材向前料中的溶解受温度的影响很大;但温度过高,超过550 时,母材有所软化,母材性能受到影响,因此本试验选择的钎焊温度范围为390

9、500。经第一次加热涂敷Zn-Al钎料的两个试件,再经火焰二次加热,并同时进行加压,使两试件连接在一起。在焊接压力为30 MPa时,不同的二次加热温度,对接头拉伸强度产生了不同的影响,其结果如图2所示。由于经一次加热涂敷Zn-Al钎料及刮擦后,此时钎料将是一种新成分的Zn-Al合金,并含有SiC晶须。由Zn-Al二元相图知,当Zn含量减小,Al含量增加时,固液相线温度升高,因此在390440 二次加热范围内,此新成分钎料正处于固液两相区,没有完全熔化,因而在随后冷却凝固过程中,组织不均匀,流动性变差,易产生微观缩孔,导致接头强度下降。因此,在390440 时,随温度升高,新成分钎料流动性增强,

10、液相多,固相少,冷却凝固时,微缩孔少,抗拉强度随之增加。当Tb=450 时,新成分钎料已完全熔化,在压力作用下,可更好地向微观缺陷处渗透、填充,冷却凝固时,得到致密钎缝,因而,当焊接压力为30 MPa时,接头抗拉强度可达到母材强度的85%90%。图2 钎焊温度对接头强度的影响Fig.2Effects of soldering temperature ontensile strength of soldered joint2.2 焊接压力图3是在Tb=450 时,压力对接头抗拉强度的影响。当焊接压力在030 MPa,接头抗拉强度随压力增加而增加,这是因为图1所示的加压过程中第3阶段钎料处于液态,

11、第4阶段钎缝合金逐渐由液固状态转变为高温固相状态。当在第3阶段,压力030 MPa,随压力增加,钎缝中液相Zn-Al钎料被挤出越来越多,原来的Zn-Al合金变成了Zn-Al合金+SiC晶须复合钎料,且随压力增加,被挤出的液态合金越多,使SiC晶须留在钎缝中的相对比例也越高,因而钎缝强度也增加;另外在第4阶段压力升高,有利于在固-液态治愈缩孔,使钎缝组织致密,也进一步提高接头强度。当压力达到30MPa时,接头强度达到最大为263.3 MPa。当压力达到50 MPa时,接头强度下降,并出现突出变形,这是因为压力太大,液态钎料挤出太多,使钎缝SiC47焊 接 学 报第22卷晶须比例大大增加,进而冷却

12、凝固时出现了较多微缩孔,导致接头强度反而下降。图3 压力对接头抗拉强度的影响Fig.3Effects of soldering pressure ontensile strength of soldered joint图4是不同焊接压力下钎焊接头的电镜扫描照片。由图4a可看到pb=1 MPa的钎缝全貌,发现钎缝比图4c的宽,而且从图4a中可看到在钎缝中有微缩孔(图中左右两侧为母材,中间白亮带为钎缝),这表明Zn-Al钎料层并不致密。正如文献6所述,对焊接头在焊合过程中,界面处由于固态SiC晶须的存在,使此处新成分合金流动性变差,在随后冷却凝固过程中新成分Zn-Al合金存在二相区。当固相多时,流

13、动性进一步恶化,因此在钎缝冷却过程中由于钎缝各部分收缩率不同而又无充足的金属液填充微区域的冷凝收缩。且该过程的焊接压力pb=1 MPa也较小,无法治愈缩孔,因而钎缝中出现较多缩孔。当pb增加时,加压有利于通过流变、蠕变及塑性变形治愈凝固过程中产生的缩孔,使钎缝致密,宏观表现为钎缝厚度减小。另外压力还可促进钎缝中Al与SiC晶须之间发生半共格润湿,进而通过Al/SiCw界面润湿及结合提高复合材料综合性能7。这有利于Zn-Al/SiCw复合钎料自身强度提高,并最终导致钎缝、钎缝/母材界面致密,使接头强度提高。如图4b、4d分别为pb=1 MPa、pb=30MPa钎缝/母材界面。很明显,pb=30

14、MPa的钎缝组织要比pb=1 MPa的致密。在本试验中,当pb=30 MPa时,可得到致密钎缝。2.3 刮擦作用分析由图4b、4d还可以看出,无论是焊接压力pb=1 MPa还是pb=30 MPa的母材/钎缝界面,其界面结合都非常紧密,钎料层中分布着相当数量的SiC晶须。这表明第一次加热过程中的机械刮差,使相当数量的SiC晶须过渡到钎料层中,钎料已变成含SiCw的复合钎料。晶须在钎缝的存在一方面可发挥其对钎缝的增强作用,改善钎缝强度;另一方面使钎缝组织更加接近母材组织(或一致),因而钎缝的物理特性(如热胀系数等)和化学特性(如抗腐蚀性等)与母材的更接近,这对获得具有优良综合性能的钎焊接头大有裨益

15、。图4 不同焊接压力下钎焊接头的SEM照片Fig.4SEM photographs of soldered joint underdifferent soldering pressure2.4 断口分析图5是焊接压力pb对接头拉伸断口形貌的影图5 不同焊接压力下的接头拉伸断口SEM照片Fig.5SEM fractographs of soldered joint underdifferent soldering pressure57第4期吕世雄,等:SiCw/6061Al复合材料无钎剂加压钎焊响,图5a是pb=1 MPa时的拉伸断口,主要有小韧窝+准解理+少量SiC晶须+拉拔掉SiC晶须残留凹

16、坑。断面的SiC晶须很少,其强化作用不明显,所以接头强度较低。图5b是pb=30 MPa时的拉伸断口,主要有小韧窝+准解理+较多SiC晶须+拉拔掉SiC晶须残留凹坑,SiCw与基体结合紧密,SiC晶须数量增多,增强作用明显,所以接头抗拉强度提高。其断口经X衍射相结构分析为-Al(Zn)固溶体+SiC晶须,没有发现Al4C3等金属间化合物。3 结 论本文提出了一种无钎剂加压钎焊SiCw/6061复合材料的新方法,采用Zn-Al钎料进行了焊接试验。工艺试验结果表明,当Tb=450;pb=30MPa时,接头抗拉强度b=263.3 MPa,为母材强度的85%90%;刮擦工艺有助于液态Zn-Al钎料/母

17、材相互作用,并促进其相互扩散、溶解、迁移,使钎料成为新成分的Zn-Al合金,并含有SiC晶须的复合钎料。断口形貌分析表明,其拉伸断口为小韧窝+准解理+SiC晶须,当pb=30 MPa时,断口形貌中SiC晶须增加,X射线衍射相结构表明此断口由-Al(Zn)固溶体+SiC晶须构成。参考文献:1Ellis M B D,Gittos M F,Threadgill P L.Joining aluminum basedmetal compositesJ.Mater.World.1994,2(8):415417.2Wu X,Li H,Chandel R S,et al.Effect of mechanica

18、l vibration onTLP brazing with BNi22 nickel2based filler metal J.J.Mater.Sci.Lett.2000,19(4):319321.3Moshier W C,Ahearn J S,Cooke D C.Interaction of Al2Si,Al2Geand Zn2Al eutectic alloys with SiC/Al discontinuously reinforcedmetal matrix compositesJ.J.Mater.Sci.1987,22(1):115122.4Partridge P G,Dnford

19、 D V.The role of interlayers in diffusionbonded joints in metal-matrix compositesJ.J.Mater.Sci.1991,26(8):22552258.5Bushby R S,Scott V D.Liquid phase bonding of aluminum andaluminum/Nicalon composite using copper interlayersJ.Mater.Sci.Technol.1993,9(5):417423.6 刘黎明.铝基复合材料非夹层液相扩散焊机理研究D.哈尔滨:哈尔滨工业大学,2

20、000.7 崔 岩.SiCp/6061Al复合材料的制备及界面研究D.哈尔滨:哈尔滨工业大学,1997.作者简介:吕世雄,男,1957年9月出生,硕士,工程师。研究方向为铝合金焊接、铝基复合材料焊接。发表论文8篇,专利1项。(编辑:闫秀荣)欢迎订阅 敬请赐稿 欢迎刊登广告中国表面工程由中国机械工程学会主办的 中国表面工程 是促进我国表面工程学科发展,体现中华民族优秀文化传统,反映表面工程所具有交叉、综合、复合、系统的特点,并与国际表面工程行业交流的专业技术杂志。本刊综合报道国内外表面科学与工程发展方向及现状,刊登国内外表面工程的理论研究和实际应用成果,传播最新科技动态与实用信息,介绍应用表面工

21、程技术提高产品质量、解决维修技术关键、促进科技转化为生产力、增加企业效益的经验。力求学术水平高,创新性强。本刊坚持理论联系实践,研究、开发与推广应用相结合。读者对象是广大工程技术人员。本刊是大专院校、科研院所、工矿企业科技人员学术交流的园地,教学科研的助手,资料查询的知识库。本刊为季刊,大16开,52页,国内外公开发行。国内邮发代号:82-916国内发行处:北京报刊发行局国内定价:每期6.00元,全年24.00元。欢迎读者到当地邮局订阅,也可直接与本刊编辑部联系。编辑部地址:北京长辛店杜家坎21号 邮政编码:100072电 话:(010)6671887366719325传 真:(010)667

22、18871电子信箱:cse 广告经营许可证:京丰工商字第060189号国外发行代号:1393Q国外总发行:中国国际图书贸易总公司(北京399信箱)67焊 接 学 报第22卷LY12 alloy is 4mm,the diameter rate of rotation tool shoulder and the weld2ing pin with special profile is 3:1,the rate of the diameter of the pin and thethickness of welded material is 1:1,the welding speed is 37.

23、5mm/min andthe rotation speed is 2000r/min,a joint of high quality is formed.The resulthas laid a theoretical and experimental foundation for further research forFriction Stir Welding.K ey words:friction stir welding;aluminium alloy;technological researchStudy on Elimination of Martensitic Shortness

24、 Layer for Dissimilar SteelWeldW ANG Ai2zhen(Zhengzhou Light Industry College,Zhengzhou450002,China),ZHANG T ai2chao,ZhAO Hong2yan.5862Abstract:In this paper the weldability of 1Cr18Ni9Ti and 15CrMosteels is analysed by magnetic recongnizer and scanning electromicroscope.Main factor of forming marte

25、nsitic shortness layer is discovered in the weld atnormal temperature and continuous high temperature.The effect law of dif2ferent welding material and technology on ingredient and microstructure andperformance of joint are discussed.And change law of martenstic shortnesslayer conent at different st

26、ate is also discussed.A effective method of pre2sur2faced 8 mm thick transition layer of pearlitic new R417 electrode,then de2positing austenitic A307 complex alloy on 15CrMo side beveled surface in1Cr18Ni9Ti and 15CrMo joint has been created.This method hasfully elimi2nated martensitic shortnesslay

27、er of dissimilar steel joint at the normal temper2ature and high temperature.It solved welding problemof pipeline joint in am2monia synthetic tower and provided some reference for joint in other chemicalpressure equipment.K ey words:austenitic steel;pearlitic steel;martensitic organization;shortness

28、 LayerJoining Mechanism of Field2assisted Diffusion Bonding of Borosilicate G lassto MetalsMENGQing2sen(Instituteof Weldingof XianJiaotong Uni2versity,Xian 710049,China),Yu Pin,Zhang Li2na,Xue jin.p6365Abstract:The features of microstructure in the boding interface arca offield2assisted diffusion bo

29、nding(FDB)of glass to metal have been studied,bonding mechanism and its influence factors have been analyzed by meams ofSEM,EDX and XRD,for which the bondingof electrolyte glass to moncrystalsilicon and aluminum has been used as examples.The models of“metal2ox2ides2glass”of joining structure and ion

30、s diffusion bonding are indicated.A spe2cial bonding machine is used,voltage is 400800 V,pressure is 0.051.0MPa,temperature is 250400.The present study concludes that the join2ingforming is contributed byprocessof oxygen ionsflowing and bonding withmetal ions and deposited in the interface;the volta

31、ge,temperature,pressureand surface roughnessof test wafers are influence factorsfor ionsflowing andbonding;the pillar shape microsturcture in the transitional area is favorable tobonding strength.K ey words:glass;metal;field2assisted difusion bonding;transitional ar2ca.Effects of Laser Shock Process

32、ing on The Mechanical Properties of WeldedJoints()ZOU Shi2kun(Beijing Aeronautical Manufacturing T echnologyResearch Institute,Beijing 100024,China),W ANG Jian,W ANG Hua2ming.p6668Abstract:The welded zones of GH30 and 1Cr18Ni9Ti were shock2pro2cessed bypulse laser in last paper,the results showed th

33、at the limit strengthofGH30 welded joints was increased by 12%but the effect on fatigue life wasnot obvious,at the meantime,the limit tensile strength of 1Cr18Ni9Ti weldedjoints was increased by only 5%but the fatigue life was increased by morethan 300%.For further investigations,the distribution of

34、 microhardness andresidual stress of welded zones were measured and the fatigue fractures wereanalyzed by SEM.After laser shock processing,the limit strength of GH30welded joints and the microhardness in the surface layer were increased,sur2face residual compress stress was improved.Fatigue initiati

35、on and crackgrowth were held back and crack growth rates were reduced in the strength2ened zones,but the shock spot did not cover the welded jointsor HAZentire2ly,unshocked zones did harm to the fatigue properties;martensite phase wasformed in plasma welding 1Cr18Ni9Ti,which reduced the effect of st

36、rain de2formation martensite induced by laser shock processingon the microhardness,so laser shock processing had less effect on the strength of 1Cr18Ni9Ti weld2ed joints,but the surface residual compress stress gained by laser shock pro2cessing could obviously improve the fatigue life of 1Cr18Ni9Ti

37、welded joints.K ey words:laser shock processing;weldedjoints;microhardness;resid2ual stress;fatigue fractureThe Corrosion Behaviors of Welded Joints of 3C Carbon Hull StructuralSteelsW ANG Su2hua(Institute of Naval Aviation Engineering,264001,China),ZHU Mei2wu,KONG Xiao2dong,CHEN Xue2qun.p6972Abstra

38、ct:Two kindsof carbon hull structural steels(the 3C steel whichis Re2free and the 3C corrosion resistant steel which is modified by Re)andthree kinds of welding consumables are selected and made into six kinds ofwelded joint specimen.The difference of corrosion behaviors of six weldedjoint specimen

39、and distinct zones of the welded joint specimen have been in2vestigated by meansof laboratory stirringimmersion test,dry2wet intermittenttest and constant potential anodic dissolution test.Furthermore,conbined withthe metallurgical analysis,the reason which makes these corrosion results arediscussed

40、.The results indicate that the weld zone and base metal show morecorrosive than the heat2affected zone(HAZ),while the weld zone is easier tocorrode than the base metal.Not only is the corrosion resistance of structuralsteel improved itself with Re additions,but also the corrosion resistance of thest

41、eel welded joint is also improved correspondingly(compared to the samewelding consumable).For Both the 3C steels which are Re2free and the 3Ccorrosion resistant steel which is modified by Re,the corrosion resistance ofwelded joint using J422 consumable is higher than using other two weldingconsumabl

42、es.K ey words:carbon steel;welded joint;seawater;corrosionFluxless Pressure Soldering for SiCw/6061Al CompositesLShi2xiong(National Key Labortory of Advanced Welding Production T echnology,HIT150001,China),YAN Jiu2chun,XU Zhi2wu,YANG Shi2qin,WU lin,YUZhi2shui.p7376MAIN TOPICS,ABSTRACTS&KEY WORDS 200

43、1,Vol.22,No.4Abstract:A new soldering method2fluxless pressure soldering for SiCw/6061Al composites was presented,and welding experiments for the effects oftwo parameters:the soldering temperature and pressure related to solderedjoint strength and microstructure were carried out by using the Zn2Al f

44、illermetal.The contribution of assistant process222scrape was also discussed.Theexperimental results show that temperature andpressure are two key solderingprocess parameters,when the soldering temperature is in the range of 400450and the pressure is 30 MPa,the tensile strength of soldered jointreac

45、hes 252.0263.3MPa,which is up to 85%90%of that of base met2al.A number of microdimples,SiCwwhiskers,considerable quasicleavage to2gether with residual pits of SiC whiskers are observed on the fracture,whichidentifies the reinforcement of SiC whiskers to the soldering seam.Moreover,the resultsof X2ra

46、y diffraction analysisindicate that the soldering seam mainlyconsists of a2Al(Zn)solid solution and uniform SiC whiskers.K ey words:aluminum matrix composite;soldering;pressure;mi2crostructureThe Finite Difference Calculation of Carbon Migration in Disimiar MetalWeldmentsYANG Hou2jun(Central China P

47、ower Corporation Group,Wuhan 430077,China),SHI Gang,ZHANG Ying2lin,LU Wen2guang,CAOSheng.p7780Abstract:The analytic solution of carbon migration in dissimilar metalweldments(DMWs)had been researched by many researchers,because of theidealization of assumed conditions,it caused bigger difference betw

48、een the ana2lytic and testing result.In this paper,numerical solution of carbon diffusionwas solved and the finite difference method was used,inner boundary condi2tions of the meshes were treated using diffusional flux and carbons activity,the stability and the convergence equation were dissussed.Th

49、e systemof iden2tification indicated that the numerical results were accordant to the experi2mental results.K ey words:DMWs;carbon migration;finite difference method;calcu2latin.Mathematical Model and Simulation on Dynamic Process of Droplet ShortCircuiting T ransferZHANGJun2hong(Beijing University

50、of Aeronauticsand Astronautics,100083,China),HUANG Shis2heng.p8183Abstract:It is a difficult task to study the many controll parameters ofwaveform control method.In order to solve this problem,a methematicalmodel of the droplet short circuiting transfer dynamic process in CO2gasshielded arc welding