【130论文翻译】TiAl基合金与钢的高频感应钎焊.pdf

1 tialtialtialtial 基合金与钢的高频感应钎焊基合金与钢的高频感应钎焊基合金与钢的高频感应钎焊基合金与钢的高频感应钎焊 t.noda*,t.shimizu, m. okabe,t.iikubo 大同钢铁公司特种钢研究所，日本，南新宿名古屋 457 号 摘要：研究了高频感应钎焊工艺，以期得到一种低成本、高强度的 tial 基合金与钢 的焊接接头。结构钢 aisi4340 和铸造钛铝基合金ti33.5al0.5cr1nb0.5si 作为母 材，分别用银基钎料 63ag35.2cu1.8ti（cusil-aba）和钛基钎料 70ti15cu15ni （ticuni）做钎料进行焊接试验。钎焊温度比钎料液相线温度高 15k，钎焊保温时 间为 30s。研究表明，ticuni 钎料熔化后与母材的反应比 cusil-aba 钎料更激烈； 此外，采用 cusil-aba 钎料焊接时，结构钢与钎料反应，在结构钢一侧形成碳化物 层，因此钎焊接头强度远高于 ticuni 钎料的接头强度。采用 cusil-aba 钎料进行 高频感应钎焊，在室温下，接头强度可达 320mpa，在 773k 温度下，接头强度为 310mpa。 关键词：接头强度；tial 基合金；高频感应钎焊；cusil-aba；ticuni 1 1前言前言 各种金属间化合物中，tial 基合金是已发现的最轻的耐热材料。tial 基合金已 广泛应用于航空航天和汽车零部件产业1,2。tial 基合金在零部件的实际应用中，高 频感应钎焊技术的研究对合金成分设计、零件加工、表面处理和焊接等技术有重要的 意义。因此，研究发展 tial 基合金和具有优良的耐磨性和韧性结构钢高频感应钎焊 技术很有必要。 已报道的文献中关于 tial 基合金的焊接技术有： （1）钎焊：真空钎焊1和红外线 钎焊3； （2）摩擦焊3,4； （3）扩散焊5； （4）熔化焊：电子束焊6和电容储能焊7。 但是，这些方法大多只是用于 tial 基合金同种金属的焊接，没有用于 tial 基合金与 钢的焊接。这些方法中，只有真空钎焊和摩擦焊已用于 tial 基合金和钢的焊接1,4， 但是，摩擦焊焊接 tial 基合金和钢时，焊后冷却过程中，由于马氏体相变产生的内 应力导致接头在界面处产生脆性断裂。 tial 基合金与钢的焊接的关键问题是如何在接 头处避免脆性相的生成以及如何减小应力。钎焊过程中，钎料的存在缓冲了应力的作 用，因此，tial 基合金与钢可采用钎焊连接。tial 基合金与钢的真空钎焊研究表明， tial 基合金是一种活泼材料， 从工业生产的角度看， 尤其是对汽车行业， 由于成本高， 采用真空钎焊是不切实际的。为了得到一种低成本、高强度的 tial 基合金与钢的焊 2 接接头，本文对高频感应钎焊8技术进行了研究。 2 2试验方法试验方法 2.12.1 实验材料实验材料 由于铸造 tial 基合金 rnt004（ti33.5al0.5cr1nb0.5si）受铸造条件限制， 经过离子体铸造炉熔炼和铸造成 5 kg 的淀坯，在用电火花切割成 10mm 直径的钢筋。 选用 13mm直径的轧钢aisi4340(fe0.4c0.7mn0.2si1.8ni0.8cr0.2mo)作为结构 钢母材。这些材料加工成直径为 8.15mm，长 45mm 的棒材，连接表面用型号为 c80 的砂轮研磨机打磨。 2.22.2 钎料钎料 在该试验中， 选用两种钎料。 一种是用于金属和陶瓷连接的活性银基钎料cusil， 另一种是用于钛合金连接的钛基钎料 ticuni。目前 ticuni 已成功的应用于同种 tial 基合金的焊接3。 钎料的成分和液相线温度如表 1 所示。 cusil - aba 和 ticuni 钎料形状分别为 50 微米和 100 微米厚的薄片。 2.32.3 高频感应钎焊高频感应钎焊 高频感应钎焊示意图如图 1 所示。该方法的特点是加热快和冷却快。把钎料放在 两母材之间并施加一点压力压紧钎料， 用高频感应器迅速加热接头到钎焊温度并保持 在这个钎焊温度下加热。在试样周围通入氩气防止在钎焊试样被氧化。钎焊温度比钎 料液相线温度高 15k，钎焊保温时间为 30s。 表 1钎料成分及其液相线温度 agagagagtitititininininicucucuculiquidus(k)liquidus(k)liquidus(k)liquidus(k) cusil-abamass%63.01.835.21088 mol%49.73.047.3 ticunimass%7015.015.01233 mol%74.813.112.1 2.42.4 质量评估质量评估 接头试样加热至 873k，保温 1800s 消除接头的应力，然后在进行测试。通过光 学显微镜和扫描电镜(epma)观察接头的显微组织。在室温和 773 k 温度下，对 5mm 直径的试样进行拉伸试验，测量其接头强度。 3 3.3. 结果与讨论结果与讨论 3.13.1钎料的润湿性钎料的润湿性 接头外观如图 2 所示。有研究表明，熔化钎料润湿 tial 后从接头内部被挤出。 图示表明， 两种钎料对 tial 基合金具有良好的润湿性， 而对结构钢 aisi4340 不润湿。 3.23.2接头微观组织接头微观组织 接头的光学显微组织如图 3 所示。在 10-20微米倍数下观察 cusil-aba 钎焊的 接头钎缝，在 20-30 微米倍数下观察 ticuni 钎焊的接头钎缝。这两个接头均为显示 任何孔洞缺陷和裂纹，接头成形良好。 3.33.3 cusil-abacusil-aba钎料钎焊的接头组织钎料钎焊的接头组织 cusil-aba 钎料钎焊接头的电子显微组织如图 4 所示。在钎缝中发现了两种相 组织： （1）在 aisi4340 一侧形成富银相 a，相 a 含有铜和少量 c 和 fe； （2）在 tial 一侧形成富铜相b，相 b 含钛和铝。很明显，在熔化的钎料反应，cusil，脱落酸， 与 aisi4340 和 tial 基发生。很明显，在熔化的 cusil-aba 钎料会与 aisi4340 和 tial 基合金发生反应。 然而， 熔化的 cusil-aba 钎料与 aisi4340 的反应弱于与 tial 基 合金 的反 应。 由富 银 a 相 的定 量分 析结 果得 知， 除了 c ， 其组 分为 图 2 接头外观示意图 (a) cusil-aba; (b) ticuni 图 1 高频感应钎焊 4 54ag33cu10fe2ti1al。除了铝和钛，在银，铜，铁三元相图中没有发现其他的 单一相9。在现阶段发现的只有一种银，铜，铁三元共晶相。因此，该富银 a 相推定 为三元共晶相。 另一方面， 对富铜相 b 进行分析， 其成分确定为 63cu24ti12al1ag （摩尔） 。从铝，铜，钛三元相图10看，其组成相是 alcu2ti 金属间化合物。 3.43.4 ticuniticuni钎料钎焊的接头组织钎料钎焊的接头组织 ticuni钎料钎焊接头的电子显微组织如图5 所示。 在钎缝中发现了三种相组织： （1）在 aisi4340 一侧形成富钛相 a，相 a 含有铜和少量 ni 和 cu； （2）在 tial 基 合金中含富钛相b，相 b 含大量的钛和和少量的铝；且钎缝 tial 基合金侧含少量的 ni 和 cu。 （3）aisi4340 和富钛相 a 之间的碳化物层和富钛相 a 与 b 之间的碳化物 (b) ticuni 图 3 接头的光学显微组织 (a) cusil-aba 图 4cusil-aba 钎料钎焊接头的电子显微组织 5 球。这些相的形成表明，特别是碳化物相，与 cusil aba 相比，钎焊时熔化的 ticuni 钎料与 aisi4340 和 tial 基合金很反应强烈。这种现象是由于 ticuni 的钎焊温度比 cusilaba 的钎焊温度高以及高温下钛钎料固有活性高。扫描电镜能 谱分析表明，除了 c，富钛相 a 和 b 的成分分别为 53ti-27fe-13al-4ni-3cu（mol） 和 62ti-22al-12fe-2ni-2cu（mol） 。除了少量的 ni 和 cu，可用tialfe 三元相图 来确定这两个相的成分11。由相图可知，富钛相 a 和 b 分别是 fe ti, alti 和ti3al， ti3fe。由tifec 三元相图分析， 在 cusil aba 钎缝金属中没有观察到的碳化物 相，可能是 tic 碳化物的硬质合金。 3.53.5 接头强度接头强度 图 6 所示是两接头及母材 aisi4340、 tial 基合金的拉伸强度。在室温和 723k 温 度下，尽管 cusilaba 钎焊的接头拉伸强度比 ticuni 高，但接头强度都没有达到 母材 tial 基合金和 aisi4340 的拉伸强度。采用 cusilaba 钎焊时，室温接头强度 可达 320mpa，在 773k 温度下，接头强度为 310mpa，等于或高于同种 tial 基合金 真空钎焊1和扩散焊5的接头强度。实际应用中都应充分考虑这些优点。 图 5ticuni钎料钎焊接头的电子显微组织 6 两接头的断裂都发生在接头界面处。在室温下，接头断裂截面的电子显微形貌如 图 7 所示。这些图像表明，使用 cusilaba 钎焊的接头的断裂发生在 aisi4340 和 钎缝金属界面处及 tial 基合金与钎缝金属界面处。而使用 ticuni 钎料钎焊时，接 头沿着富钛相 a 与 aisi4340 之间的碳化物层发生断裂。这表明，碳化物层导致 ticuni 钎料钎焊接头强度低。钛对碳具有强烈的亲和力，从而形成碳化物。结果表 明，适合同种 tial 基合金钎焊的钛基钎料并不适合 tial 基合金与结构钢的钎焊3。 因此，与结构钢相互反应不产生碳化物层的 cusilaba 钎料可用来 tial 基合金与 结构钢的钎焊。 图 6接头拉伸强度 图 7 接头断裂截面的电子显微形貌：(a, b) cusil-aba；(b, c) ticuni 7 4.4. 结论结论 以银基钎料 cusil-aba 和钛基钎料做钎料，进行了 tial 基合金和结构钢的高 频感应钎焊研究。结果表明： （1）ticuni 钎料熔化后与母材的反应比 cusil-aba 钎料更激烈。结果， cusil-aba 钎缝金属中没有观察到碳化物相，而在 ticuni 钎缝金属与结构钢的界 面处形成了碳化物相。 （2）使用 cusil-aba 钎料焊接时，结构钢与钎料反应，在结构钢与钎缝金属 界面一侧形成碳化物层，钎焊接头强度高于 ticuni 钎料的接头强度。 （3）使用 cusil-aba 钎料进行高频感应钎焊，在室温下，接头强度可达 320mpa，在 773k 温度下，接头强度为 310mpa。 参考文献 1y.nishiyama,t.miyashita, s. isobe,t. noda,in:s.h. hang et al. (eds.), high temperature aluminides andintermetallics,tms,warrendale,pa,1990, p. 557. 2k. maki, a. ehira, m. sayashi,t.noda, m. okabe, s.i sobe, sae technical paper no. 960303, 1996, p. 117. 3c.a. blue, r.a. blue,r.y.lin, process.adv.mater. 9 (1994)141. 4h. horn,in:proc. eurojoin1:1st eur. conf. on joining technology, institut de soudure, paris, france, 1991, p. 441. 5y.nakao, k. shinozaki, m. hamada, isijint. 31 (1991) 1260. 6r.a. patterson, b.k. damkroger,in:proceedings of weldability of materials,asm international, materials park, ohio 44073,usa, 1990, p. 259. 7r.d.wilson, d.e. alman, j.a. hawk,in:materials research society symposium proceedings, vol. 364, materials research society, pittsburgh,pa,usa, 1994, p. 237. 8d.l. olsen, t.a. siewert, s. liu, g.r. edward,asm handbook 6, 1993, p. 333. 9p.villars,a. prince, h. okamoto,in:handbook of ternaryalloys phasediagrams, vol. 3, asm international, materials park, oh, usa, 1995, p. 2283. 10p.villars,a. prince, h. okamoto,in:handbook of ternaryalloys phasediagrams, vol. 3, asm international, materials park, oh, usa, 1995, p. 3372. 11p.villars,a. prince, h. okamoto,in:handbook of ternaryalloys phasediagrams,vol. 3, asminternational, materials park,oh, usa, 1995, p. 3628. materials science and engineering a239240 (1997) 613618 joining of tial and steels by induction brazing t. noda *, t. shimizu, m. okabe, t. iikubo special steel research department, research and de6elopment di6ision, daido steel ltd., minami-ku, nagoya457, japan abstract in order to develop the joining technology of tial and structural steels which gives a low cost and high strength joint, rapid induction brazing was investigated. the active silver based fi ller metal of 63ag35.2cu1.8ti mass% (cusil-aba) and the titanium based fi ller metal of 70ti15cu15ni mass% (ticuni) were selected. as joining materials, the structural steel aisi4340 and cast tial with composition of ti33.5al0.5cr1nb0.5si (mass%) were employed. brazing temperature and holding time were fi xed at 15 k above the liquidus temperature of the fi ller metals for 30 s. the reactions of the molten fi ller metal of ticuni with the base metals were stronger than that of cusil-aba. in addition, a carbide layer, not observed in the brazed metal of cusil-aba, was formed at the interface of aisi4340 and the brazed metal. the strength of the joint using ticuni was inferior to that of cusil-aba due to the formation of the carbide layer at the interface of aisi4340 and the brazed metal. by rapid induction brazing using cusil-aba fi ller, a joint strength of 320 mpa at room temperature and 310 mpa at 773 k was obtained. 1997 elsevier science s.a. keywords:joining; tial; brazing; induction; cusil-aba; ticuni; strength 1. introduction in various intermetallic compounds, tial has been focused on as the most practical light weight heat-resis- tant material. studies of the practical application of tial for components in aerospace and automobile in- dustries have been carried out 1,2. in the practical application of tial to the components, technology developments not only in alloy design but also in processing, surface modifi cation and joining are neces- sary. particularly, the technical development of the joining of tial and structural steels with excellent wear resistance and toughness is required. reported joining techniques concerning tial in liter- ature are (1) brazing involving vacuum brazing 1 and infrared welding using a fi ller metal 3; (2) friction welding 1,4; (3) diffusion bonding 5; (4) fusion weld- ing such as electron beam welding 6 and capacitance discharge welding 7. however, most of them did not deal with the joining of tial and steels but with joining of the same tial. the techniques applied to the joining of tial and steels were vacuum brazing 1 and friction welding 1,4 only. moreover, the friction welding of tial and a structural steel was not successful because of cracking at the brittle interface of a joint due to the internal stress induced by the martensitic transforma- tion of the structural steel on cooling after joining. the key point of joining tial and structural steels is how to avoid the formation of brittle phases and alleviate the stress at the interface of the joint. in brazing, the direct joining of tial and structural steels is possible because a fi ller metal acts as the buffer for the stress. the reported brazing of tial and structural steels was car- ried out in vacuum because tial is an active material. from an industrial point of view, especially for the automobile industry, vacuum brazing is impractical due to its high cost. in this study, in order to develop low cost joining techniques for tial and structural steels with high joint strength, rapid induction brazing 8, being a high effi ciency brazing method, was investi- gated. 2. experimental procedure 2.1.materials as the base metal of tial, rnt004(ti33.5al 1.0nb0.5cr0.5si mass%) tailored for cast alloy was employed in as-cast condition. after melting and cast-* corresponding author. 0921-5093/97/$17.00 1997 elsevier science s.a. all rights reserved. piis0921-5093(97)00638-2 t. noda et al./materials science and engineering a239240 (1997) 613618614 table 1 composition and liquidus of two fi ller metals ticuliquidus (k)niag 1.835.21088cusil-abamass%63.0 47.3mol%49.73.0 15.015.01233ticuni70.0mass% 12.1mol%74.813.1 ing into 5 kg ingots by a plasma skull casting furnace, 10 mm diameter bars were cut out by edm. rolled barsofaisi4340(fe0.4c0.7mn0.2si1.8ni 0.8cr0.2mo, mass%) with 13 mm diameter were em- ployed as the base metal of structural steel. these materials were machined into 8.15 mm diameter and 45 mm long bars and their joining surfaces were fi nished by a grinding machine with c80 grinding wheel. 2.2. brazing fi ller metals in this study, two types of fi ller metals were selected. one is the active silver based fi ller metal, cusil-aba, tailored for joining of metals and ceramics. another is the titanium based fi ller metal, ticuni, used for the joining of titanium alloys. recently this fi ller metal was applied to the joining of the same tial and successful results were obtained 3. their chemical compositions andliquidustemperatureareshownintable1. cusil-aba and ticuni fi ller metals were in the form of sheets with thickness of 50 and 100 mm, respec- tively. 2.3.induction brazing the schematic illustration of the induction brazing is shown in fig. 1. this method is characterised by rapid heating and cooling. after a sheet of fi ller metal is placed between tial and aisi4340 under a slight pres- sure to hold the specimens, the joint position was rapidly heated up to and kept at brazing temperature by induction heating. in order to prevent oxidation of the specimens during brazing, ar gas was passed into a quartz tube around the specimen. the brazing tempera- ture and holding time were respectively fi xed at 15 k above the liquidus temperature of the fi ller metals and 30 s. 2.4.e6aluation before the evaluation tests, joined specimens were subjected to post-joining heat treatment at 873 k for 1.8 ks for stress relief of the joints. the microstructures of the joints were observed by an optical microscope and an electron probe micro-analyzer (epma). in or- der to evaluate joint strength, tension tests at room temperature and 773 k were carried out using the specimens with a guage section of 5 mm diameter. 3. results and discussion 3.1. wettability of fi ller metals the outer view of joints are shown in fig. 2. it was observed that the fi ller metals discharged from the fig. 1. schematic illustration of the induction brazing. fig. 2. outer view of joints using two types of fi ller metals: (a) cusil-aba; (b) ticuni. t. noda et al./materials science and engineering a239240 (1997) 613618615 fig. 3. optical micrographs of joint cross-sections using two types of fi ller metals: (a) cusil-aba; (b) ticuni. that with tial. as a result of quantitative analysis of the ag-rich phase a, except for c, its composition was determined to be 54ag33cu10fe2ti1al (mol%). ignoring the small amounts of al and ti, no single phase corresponding to this composition is found in the agcufe ternary phase diagram 9. the only phase existing is a ternary eutectic consisting of ag, cu and fe solid solutions. therefore, this ag-rich a phase is presumed to be the ternary eutectic. on the other hand, the cu-rich phase b was analyzed and determined to be 63cu24ti12al1ag (mol%). from the alcuti ternary phase diagram 10, the compositionally corre- sponding phase was considered to be an alcu2ti inter- metallic compound. 3.4.brazed structure of ticuni the result of epma for the joint using ticuni is shown in fig. 5. in the brazed metal, three phases were observed: (1) a ti-rich phase a containing fe and a small amount of ni and cu at the aisi4340 side in the brazed metal; (2) a ti-rich phase b containing higher ti and lower al than that in tial and a small amount of ni and cu at the tial side in the brazed metal; (3) a carbide phase layer between aisi4340 and the ti-rich phase a and a spherical carbide phase between the ti-rich phases a and b. the formation of these phases, especially carbide phases, indicate that the strong reac- tions of the molten fi ller metal of ticuni with aisi4340 and with tial occurred during brazing, as compared with the case of cusil-aba. these reac- tions are considered to be attributed to the higher brazing temperature for ticuni than for cusil- aba and the inherent activity of the titanium based fi ller metal at high temperature. from the quantitative analysis of epma, except for c, the compositions of the ti-rich phases a and b were determined to be 53ti27fe13al4ni3cu (mol%) and 62ti22al 12fe2ni2cu (mol%), respectively. by ignoring the small amounts of ni and cu, the tialfe ternary phase diagram 11 can be applied to identify these two phases. from this phase diagram, the ti-rich phases a and b corresponding to the above compositions are considered to be (fe, al)ti and ti3(al, fe), respec- tively. the carbide phases, which were not observed in the brazed metal of cusil-aba, are estimated to be tic carbide from the tifec ternary phase diagram. 3.5.joint strength fig. 6 shows the tensile strength of the two joints and the base metals of aisi4340 and tial. although the tensile strength of the joint using cusil-aba was higher than that of ticuni at room temperature and 723 k, its strength did not reach the tensile strength of the base metals of tial and aisi4340. however, the joining interfaces after the melting of them wetted the tial. this fact implied that both fi ller metals had good wettability not for aisi4340 but for tial. 3.2.joint microstructures the optical microstructures of the joints are shown in fig. 3. in the joint using cusil-aba, 1020 mm of brazed metal was observed. on the other hand, in the joint using ticuni, 2030 mm of brazed metal was seen. both joints did not show any defects such as voids and disconnected area and had sound joint interfaces. 3.3.brazed structure of cusil-aba the result of epma for the joint using cusil-aba is shown in fig. 4. in the brazed metal, two phases were observed: (1) an ag-rich phase a containing cu and a small amount of c and fe formed at the aisi4340 side; (2) a cu-rich phase b containing ti and al formed at the tial side. it is obvious that reactions of the molten fi ller metal, cusil-aba, with aisi4340 and with tial occurred. however, the reaction of the molten fi ller metal, cusil-aba, with aisi4340 was weaker than t. noda et al./materials science and engineering a239240 (1997) 613618616 fig. 4. results of epma for the joint using cusil-aba. fig. 5. results of epma for the joint using ticuni. strength of the joint using cusil-aba, 320 mpa at room temperature and 310 mpa at 773 k, was equal to or higher than that of the joints by the vacuum brazing 1 and by the diffusion bonding of the same tial 5. these strengths are considered suffi cient for practical applications. the fracture of both joints occurred at the interface of the joints. sem micrographs of the cross-section fractured surfaces of joints tested at room temperature are shown in fig. 7. these photographs indicate that the fracture of the joint using cusil-aba occurred at both the aisi4340/brazed metal and the tial/brazed t. noda et al./materials science and engineering a239240 (1997) 613618617 fig. 6. tensile strength of joints. 4. conclusion in order to join a cast tial and a structural steel, rapid induction brazing using the active silver based fi ller metal of cusil-aba and the titanium based fi ller metal of ticuni was investigated. results ob- tained in this study are as follows. (1) the reaction of aisi4340 with the molten fi ller metal of ticuni was stronger than that of cusil- aba. as a result of the reaction, the carbide phase layer which was not seen in the brazed metal of cusil-aba, was formed at the interface of aisi4340 and the brazed metal of ticuni. (2) the strength of the joint using ticuni was inferior to that of cusil-aba due to the formation of the carbide layer at the interface of aisi4340 and the brazed metal. (3) rapid induction brazing using cusil-aba gav