高级检索

钛/钢和钛/铜/钢复合板焊接接头组织和性能

褚巧玲, 王君尧, 杨聃, 王中莹, 曹齐鲁, YANCheng

褚巧玲, 王君尧, 杨聃, 王中莹, 曹齐鲁, YANCheng. 钛/钢和钛/铜/钢复合板焊接接头组织和性能[J]. 焊接学报, 2025, 46(2): 25-35. DOI: 10.12073/j.hjxb.20240826002
引用本文: 褚巧玲, 王君尧, 杨聃, 王中莹, 曹齐鲁, YANCheng. 钛/钢和钛/铜/钢复合板焊接接头组织和性能[J]. 焊接学报, 2025, 46(2): 25-35. DOI: 10.12073/j.hjxb.20240826002
CHU Qiaoling, WANG Junyao, YANG Dan, WANG Zhongying, CAO Qilu, YAN Cheng. Microstructure and mechanical properties of welded joint of titanium/steel and titanium/copper/steel composite plate[J]. TRANSACTIONS OF THE CHINA WELDING INSTITUTION, 2025, 46(2): 25-35. DOI: 10.12073/j.hjxb.20240826002
Citation: CHU Qiaoling, WANG Junyao, YANG Dan, WANG Zhongying, CAO Qilu, YAN Cheng. Microstructure and mechanical properties of welded joint of titanium/steel and titanium/copper/steel composite plate[J]. TRANSACTIONS OF THE CHINA WELDING INSTITUTION, 2025, 46(2): 25-35. DOI: 10.12073/j.hjxb.20240826002

钛/钢和钛/铜/钢复合板焊接接头组织和性能

基金项目: 国家自然科学基金资助项目(51904243)
详细信息
    作者简介:

    褚巧玲,博士,副教授;主要研究方向为新型焊接材料开发,焊接结构失效分析,焊接热应力计算;Email:chuqiaoling@xaut.edu.cn

  • 中图分类号: TG 457.11

Microstructure and mechanical properties of welded joint of titanium/steel and titanium/copper/steel composite plate

  • 摘要:

    采用电弧焊接方法(TIG/MIG)进行钛/钢(TA1/Q345)和钛/铜/钢(TA1/T2/Q345)复合板的对接焊接,借助SEM,EBSD,TEM,显微硬度、纳米压痕和拉伸试验系统研究了对接焊缝中的显微结构和力学性能. 结果表明,钛/钢对接接头中,Cu-V焊缝主要以铜基固溶体和铁基固溶体为主,局部生成的Fe2Ti相被韧性较好的铜基固溶体包围;Cu-V/ERTi-1焊缝界面处存在多种Cu-Ti和Fe-Ti金属间化合物;Cu-V焊缝与TA1/Q345界面处,存在Fe-Ti,CuTi2和β-Ti化合物. 钛/铜/钢对接接头中,Cu/ERTi-1焊缝界面处分布着多种Cu-Ti金属间化合物,分布范围较广. 钛/钢对接焊缝中Fe2Ti脆性相的硬度较高,为20.7 GPa,但由于其尺寸相对较小,因此接头的显微硬度分布与钛/铜/钢对接焊缝类似,高硬度区域均在铜基焊缝与ERTi-1焊缝界面处,达到400 HV0.3,两种对接接头中大量分布的Cu-Ti化合物的硬度处于8 ~ 11 GPa. 钛/钢异质接头的抗拉强度为440 MPa,钛/铜/钢异质接头的抗拉强度为225 MPa,断裂位置均在焊缝区域,并且铜基焊缝与ERTi-1焊缝界面处均是脆性断裂特征. 钛/钢对接焊缝中不可避免会存在Fe-Ti脆性相,虽然采用钛/铜/钢三层复合板的形式可以避免Fe-Ti脆性相的生成,但是接头中分布较广的Cu-Ti化合物仍旧是接头的一个薄弱区域.

    Abstract:

    The titanium/steel and titanium/copper/steel composite plates were butt joined by arc welding method. SEM, EBSD, TEM, microhardness, nanoindentation and tensile tests were applied to investigate the microstructure and mechanical properties. The results showed that in the titanium/steel butt joints Cu-V weld mainly consisted of Cu solid solution and Fe solid solution phases. Localized Fe2Ti intermetallics were surrounded by the soft Cu solid solution. Cu-Ti and Fe-Ti intermetallics were formed at Cu-V/ERTi-1 interface. Cu-V weld near the TA1/Q345 interface consisted of Fe-Ti, CuTi2 and β-Ti phases. A series of Cu-Ti compounds were widely distributed at Cu/ERTi-1 interface in titanium/copper/steel butt joints. Although Fe2Ti brittle intermetallics had high hardness (20.7 GPa), its limited size had less effect on the global microhardness distribution. These two butt joints had similar microhardness distribution, where high hardness values (400 HV0.3) were located at the Cu-base weld/ERTi-1 interface. The Cu-Ti compounds with wide distribution showed the hardness around 8 ~ 11 GPa.The tensile strength of titanium/steel butt joint and titanium/copper/steel butt joint were 440 MPa and 225 MPa, respectively. Both samples were fractured at the weld metal regions and brittle fracture morphology was observed at the Cu-based weld/ERTi-1 interface regions. Fe-Ti brittle intermetallics were inevitable in titanium/steel butt joint. These brittle phases were suppressed in titanium/copper/stee butt joints. However, the widely distributed Cu-Ti compounds region was the weak region of such joints.

  • 钛及其合金具有优良的耐腐蚀性能,在航空航天、石油化工、海洋工程等领域具有广阔的应用前景[1-2],但是单独采用钛制备压力容器、石油管线等大型结构件,虽可解决设备腐蚀问题,耗资巨大.以钛为覆板、以低合金钢为基板,借助炸药的爆轰作用实现高速斜碰撞而结合起来的钛/钢双金属层状复合结构,兼有钛的耐腐蚀性和钢的高强度特点,是工程实际中更为经济的选择[3-6]. 爆炸焊接方法由于可焊材料组合广泛、成本低、效率高,是大尺寸金属层状复合结构制备的主要方法[7-8],采用爆炸焊接制备的钛/钢复合板在进行后续加工时,常需要进行对接焊接,比如将复合板制备成复合管、筒体等结构件. 然而,由于钛和钢易形成脆性的Fe-Ti金属间化合物,使得钛、钢异种金属之间的对接焊接难度较大[9]. Kundu等人[10]进行了TA1和17-4PH直接扩散焊接,发现接头中存在Fe2Ti,FeTi和σ脆性相;Li等人[11]采用激光焊在TC4基体上进行了316L不锈钢的熔覆,熔覆层直接出现开裂,界面存在大量的Fe-Ti脆性相. 为了抑制其开裂,Li等人设计了TC4→V→Cr→Fe→316L过渡模式,接头中Fe-Ti脆性相被有效抑制,开裂也得到了防止;Xia等人[12]采用Ti33.3Zr16.7Cu50-xNix非晶材料作为过渡层进行了TC4和316L之间的钎焊,发现接头中依旧会存在Fe2Ti,FeTi和FeCr多种脆性相,因此,提高钛、钢异质接头的可靠性,添加过渡层是可行的途径;Adomako等人[13]采用V过渡层进行了TC4和17-4PH之间的电子束和激光焊接,配合优化的焊接工艺参数可以有效抑制焊缝中Fe-Ti脆性相的产生,但是V中间层的加入会生成σ脆性相;Wang等人[14-15]采用Cu和Cu-V复合过渡层进行了钛和钢之间电子束焊接,发现采用复合过渡层可以有效减少焊缝中Fe-Ti和其他脆性相的产生,且得到的接头强度更高,类似结果在Lee等人[16]的研究中也有报道. 因此,钛和钢异种材料的焊接采用合适的过渡层是提高接头质量的关键. 上述研究基本都是针对简单的钛和钢对接接头形式,对于钛/钢复合板这种层状结构的焊接,前期通过大量研究发现即使采用过渡层也无法避免钛和钢的局部熔化. 优化过渡层材料和焊接坡口形式,可以起到减少脆性相的含量,改变其分布模式,但是无法抑制脆性相的产生[17-20]. 鉴于此,文中提出了局部三层钛/铜/钢复合结构代替钛/钢双层复合结构进行对接焊接的思路,并设计了对接焊接坡口形式和焊接顺序.

    文中通过对钛/钢爆炸复合板的对接接头进行系统的分析和总结,确定接头的组织组成及性能薄弱区域,并进行钛/铜/钢三层复合板的对接焊接,系统分析接头各个区域的显微结构特征和力学性能,建立焊缝相组成、力学性能之间的依存关系,为异种金属层状复合结构件的推广应用提供新思路.

    文中的钛/钢、钛/铜/钢复合板均通过爆炸焊方式制备,对钛/钢、钛/铜/钢复合板进行坡口加工后,进行复合板的对接焊接,如图1图2所示,材料化学成分见表1. 钛层均选择ERTi-1焊丝进行焊接,钢层均采用ER50-6焊丝进行焊接;钛/钢复合板过渡层焊接时,选择研制开发的铜基药芯焊丝(Cu-V)进行焊接;钛/铜/钢三层复合板的铜层、钛/铜过渡层均采用ERCuSi-A焊丝(标记为Cu)进行焊接,表2为相应的焊接工艺参数.

    图  1  钛/钢复合板坡口形式及焊接顺序
    Figure  1.  Groove type and welding sequence of titanium/steel composite plate. (a) groove type; (b) welding sequence
    图  2  钛/铜/钢复合板坡口形式及焊接顺序
    Figure  2.  Groove type and welding sequence of titanium/copper/steel composite plate. (a) groove type; (b) welding sequence
    表  1  焊接材料的主要化学成分(质量分数,%)
    Table  1.  Main chemical composition of the welding materials
    焊丝CSiMnTiCuFeV
    ER50-60.080.891.51余量
    ERTi-10.03余量0.10
    ERCuSi-A3.01.0余量
    Cu-V0.010.300.50余量22.02
    下载: 导出CSV 
    | 显示表格
    表  2  焊接工艺参数
    Table  2.  Welding experiment paraments
    焊丝焊接方法焊接电流I/A电弧电压U/V焊接速度v/(cm·min−1)保护气体
    ER50-6MIG150 ~ 18020 ~ 246 ~ 780%Ar + 20%CO2
    ERTi-1TIG100 ~ 12020 ~ 223 ~ 4100%Ar
    ERCuSi-AMIG200 ~ 24020 ~ 246 ~ 7100%Ar
    Cu-V焊丝TIG140 ~ 16020 ~ 243 ~ 4100%Ar
    下载: 导出CSV 
    | 显示表格

    采用线切割制备接头组织观察试样,依次采用水磨砂纸和金刚石抛光液进行研磨、抛光处理,最后采用直径约为0.04 μm的二氧化硅悬浮液进行机械 + 化学抛光. Q345母材及ER50-6焊缝采用4%硝酸酒精溶液进行侵蚀,其余母材和焊缝采用2 mL HF + 6 mL HCl + 92 mL H2O溶液进行侵蚀;借助场发射扫描电子显微镜SEM(JEOL 7100F, SEM)和EDS能谱仪进行焊缝组织观察和成分分析;采用电子背散射衍射仪EBSD(Oxford)对相组成进行检测;采用聚焦离子束FIB(FEI Quant 3D 200)进行透射试样的制备,制备好的透射试样借助场发射透射电子显微镜TEM(JEOL 2100)进行观察及选区电子衍射测定.

    根据国家标准GB/T 2651—2008《金属材料焊缝破坏性试验 横向拉伸试验》进行焊接接头拉伸试样制备. 室温力学性能测试在万能试验机(MTS810)上进行,应变速率为2 mm/min,每种焊接接头制备3个平行试样,拉伸试验结束后,采用扫描电镜进行断口形貌观察.

    根据国家标准GB/T 27552—2021《金属材料焊缝破坏性试验 焊接接头显微硬度试验》在HV-50硬度计上进行显微维氏硬度测试,测试时相邻两点之间的测量间距为0.2 mm,加载力为2.94 N,加载时间为15 s.

    材料微观尺度下的力学性能测试在纳米压痕仪(Hysitron Triboindenter TI-950)上进行,采用金刚石材质的Berkovich压头测试,测试过程中选择力加载模式,加载速率为300 μN/s.

    图3为钛/钢复合板焊接接头的显微结构,表3图3中典型区域EDS能谱. 从图3(a)可以看出,Cu-V焊缝与底部的ER50-6焊缝结合良好;图3(b)为Cu-V焊缝中部区域的显微结构,结合表3中的数据可知,深色无规则的块状区域(谱图2)主要由铁基固溶体和少量的Fe2Ti金属间化合物组成,周围的浅色区域(谱图1)主要是铜基固溶体;图3(c)为Cu-V中部区域的相分布图,Fe2Ti金属间化合物被铁基固溶体(α-Fe)和铜基固溶体所包围,呈现断续分布模式.

    图  3  钛/钢复合板对接接头显微组织
    Figure  3.  Microstructure of titanium/steel butt joints. (a) ER50-6/Cu-V interface; (b) the central of Cu-V weld; (c) the phase map in the central of Cu-V weld; (d) Cu-V/ERTi-1 interface; (e) the high magnification image of Cu-V/ERTi-1 interface; (f) the phase map at Cu-V/ERTi-1 interface; (g) TA1/Cu-V/Q345 interface; (h) the high magnification image of TA1/Cu-V/Q345; (i) the phase map at TA1/Cu-V/Q345; (j) adjacent to Q345; (k) adjacent to TA1; (l) the phase map adjacent to Q345
    表  3  钛/钢复合板对接接头典型区域EDS能谱(原子分数,%)
    Table  3.  EDS results of the typical regions in titanium/steel butt joints
    区域FeCuVTi主要相组成
    谱图10.8095.603.60Cu
    谱图281.049.640.299.03Fe + Fe2Ti
    谱图366.535.222.5125.74Fe2Ti
    谱图411.1963.020.5025.29Cu2Ti + Cu3Ti2
    谱图525.7820.860.7152.64FeTi + β-Ti
    谱图69.7514.952.0973.21β-Ti + CuTi2
    谱图751.0719.214.0025.72Fe2Ti
    谱图828.5822.133.6845.61FeTi + Cu
    谱图910.5137.410.5951.48CuTi + FeTi
    谱图105.6030.200.8563.35CuTi2
    下载: 导出CSV 
    | 显示表格

    图3(d) ~ 图3(f)为Cu-V焊缝与ERTi-1焊缝界面处组织分布,该处界面的组织呈现连续过渡.底部靠近Cu-V焊缝的组织以亮色的铜基固溶体为主,靠近ERTi-1焊缝处,观察到Fe2Ti相(谱图3)被铜基固溶体所包围,随着与ERTi-1距离的靠近,这些铜基固溶体逐渐转变为Cu2Ti + Cu3Ti2化合物,在ERTi-1焊缝中部,组织组成转变成CuTi2和β-Ti组织,如图3(f)所示.

    图3(g) ~ 图3(i)为Cu-V焊缝与TA1/Q345复合板界面处的组织分布,该处界面呈现三角区域特征;从图3(h)高倍形貌可以看出,靠近TA1/Q345界面处以不规格块状组织为主. 结合表3可知,这些块状组织主要含有Fe,Cu和Ti元素(谱图5),根据Cu-Fe-Ti三元相图可知,组织主要为FeTi + β-Ti,这些块状组织分布在Ti元素含量较高的基体组织中(谱图6),组织主要为β-Ti + CuTi2图3(i)为该处区域对应的EBSD相分布图,富FeTi相分布在β-Ti基体上.

    图3(j)为靠近Q345基体处的组织,该处Fe2Ti(谱图7)、FeTi + Cu(谱图8)分布在铜基固溶体上;图3(l)为该区域对应的相分布图,Fe2Ti金属间化合物含量较高;图3(k)为Cu-V焊缝靠近TA1的组织,紧挨着TA1处(谱图10),Ti和Cu元素含量较高,主要为CuTi2金属间化合物,该区域宽度约为10 μm.靠近Cu-V焊缝处,由于Cu元素含量的升高,其组织呈现出柱状特征,主要为CuTi + FeTi(谱图9).在Cu-V焊缝中部区域,Cu元素含量占主导,组织主要为铜基固溶体,该处焊缝中虽然观察到了Fe2Ti和FeTi脆性相,但是其被韧性较好的铜基固溶体所包围,抗开裂能力强. Wang等人[14-15]的相关研究结果指出,脆性相的分布、含量对接头性能有重要影响. 当不可避免会产生脆性相时,其尺寸分布特征是一个重要的控制参数,这在激光焊和电子束焊方面均有相关的报道[13-15].

    为了进一步确定上述焊缝中的显微结构,采用TEM进行分析,结果如图4所示. 图4(a)为Cu-V焊缝的明场像形貌,在Cu-V焊缝中观察到粗大的Fe晶粒和Cu晶粒,其中在Fe晶粒内部可以观察到纳米尺寸的Cu析出相,如图4(b)所示. 根据Cu-Fe二元相图可知,Cu在Fe中的固溶度随着温度的降低而降低. 由于焊接非平衡凝固的特点,在高温下固溶于Fe中的Cu在降温过程中出现析出,由此形成了文中观察到的纳米尺寸的Cu析出相.

    图  4  钛/钢复合板对接接头TEM结果
    Figure  4.  TEM results of titanium/steel butt joints. (a) ER50-6/Cu-V interface; (b) Cu-V weld; (c) the diffraction of A region; (d) TA1/Cu-V/Q345 region; (e) the diffraction of B region; (f) the diffraction of C region

    图4(d)是TA1/Cu-V/Q345三角区域的明场像,结合TEM-EDS检测结果和衍射花样,确定该区域主要由FeTi相组成,其上面分布着直径约为200 ~ 400 nm的β-Ti晶粒.

    图5为钛/铜/钢对接接头的显微组织,表4为典型区域的EDS能谱,由于铜/钢一侧的组织分布较常规,重点研究钛/铜复合板一侧的焊缝组织. 图5(a)和图5(b)为Cu焊缝与ER50-6焊缝界面形貌,Cu焊缝与底部ER50-6连接良好,在靠近界面处出现深色的颗粒状物质(谱图2),结合EDS能谱数据可知,其主要为Fe基固溶体;图5(c)为T2与Cu焊缝界面形貌,Cu焊缝晶粒粗大,Cu焊缝与T2、复合板界面(T2/Q345)均结合良好.

    图  5  钛/铜/钢复合板对接接头显微组织
    Figure  5.  Microstructure of titanium/copper/steel butt joints. (a) ER50-6/Cu interface; (b) the high magnification image of ER50-6/Cu interface; (c) T2/Cu interface; (d) Cu/ERTi-1 interface; (e) the high magnification image of Cu/ERTi-1 interface; (f) ERTi-1 weld; (g) TA1/Cu/T2 interface; (h) the high magnification image of TA1/Cu/T2 interface; (i) the high magnification image of region near ERTi-1
    表  4  钛/铜/钢复合板接头典型区域EDS能谱结果(原子分数,%)
    Table  4.  EDS results of the typical regions in titanium/copper/steel butt joints
    区域FeCuSiTi主要相组成
    谱图10.1098.500.40Cu
    谱图287.7811.770.45α-Fe
    谱图352.1547.85CuTi
    谱图446.1753.83CuTi + CuTi2
    谱图532.7067.30CuTi2
    谱图653.1146.89CuTi + Cu4Ti3
    谱图712.9187.09β-Ti + CuTi2
    谱图822.8377.17CuTi2 + β-Ti
    下载: 导出CSV 
    | 显示表格

    图5(d)为Cu焊缝与ERTi-1焊缝界面处组织分布,靠近界面处主要由CuTi化合物组成(谱图3).逐渐深入ERTi-1焊缝,Ti元素含量升高,组织组成转变为长条状的CuTi + CuTi2(谱图4),如图5(e)所示;在ERTi-1焊缝中部区域,Ti元素含量进一步升高,组织组成主要为CuTi2金属间化合物(谱图5),如图5(f)所示.

    图5(g)为Cu和ERT-1焊缝与TA1/T2界面处组织分布,紧挨着Cu焊缝处,形成了一层宽约50 μm的CuTi + Cu4Ti3化合物带,紧挨着过渡层大量分布着CuTi2组织(谱图6);图5(i)为远离界面处组织分布,以亮色的网状组织为主,结合EDS结果可以发现,网状组织(谱图8)和其分布的基体组织(谱图7)均主要含有Ti和Cu元素,组织组成均为CuTi2 + β-Ti,其中网状组织中Cu元素含量较基体组织高.

    对比前面钛/钢复合板接头,铜基焊缝与ERTi-1焊缝界面处均以多种Cu-Ti化合物为主,并且这些化合物的分布范围较广. 前期采用Cu-Nb和Cu-V-Ag焊丝焊接钛/钢复合板时,靠近钛侧焊缝处也均以CuTi和CuTi2化合物为主. Ning等人[21]采用激光焊进行了CP-Ti/Q235对接连接,钢焊缝和钛焊缝之间采用铜焊缝进行过渡,在铜焊缝和钛焊缝处也发现了多种Cu-Ti相.

    为了进一步确定上述焊缝中的显微结构,采用TEM进行分析,结果如图6所示. 图6(a)为铜焊缝与ER50-6焊缝界面处的明场像;图6(b)为对应的暗场像,结合TEM-EDS能谱和该处的衍射花样,发现图中这些纳米尺寸的Fe晶粒在铜基体晶粒中析出;图6(d)和图6(e)为铜焊缝与ERTi-1焊缝界面处明场像,结合TEM-EDS和选区电子衍射,该处粗大的基体晶粒主要为CuTi2相,其上分布着直径约为300 ~ 500 nm的β-Ti晶粒.

    图  6  钛/铜/钢复合板对接接头TEM分析
    Figure  6.  TEM results of titanium/copper/steel butt joints. (a) the bright field image of Cu/ER50-6 interface; (b) the dark field image of Cu/ER50-6 interface; (c) the diffraction of A region; (d) Cu/ERTi-1 interface; (e) the high magnification image of Cu/ERTi-1 interface; (f) the diffraction of B region

    图7为钛/钢复合板接头和钛/铜/钢复合板接头显微维氏硬度分布云图. 从图7(a)钛/钢复合板对接焊缝的硬度分布可以看出,Cu-V/ERTi-1界面在ERTi-1一侧硬度较高,处于300 HV0.3以上,最高为400 HV0.3;Cu-V焊缝整体硬度较低,处于70 ~ 100 HV0.3,Cu-V焊缝在靠近TA1/Q345复合板界面处硬度较高,局部高硬度点达到400 HV0.3;TA1和Q345母材硬度较低,Q345硬度为40 HV0.3,TA1母材硬度为80 HV0.3.

    图  7  接头显微维氏硬度云图
    Figure  7.  Microhardness contours of butt joints. (a) titanium/steel butt joint; (b) titanium/copper/steel butt joint

    图7(b)钛/铜/钢复合板对接焊缝的硬度分布可以看出,Cu/ERTi-1界面在ERTi-1一侧的硬度较高,普遍处于300 HV0.3以上,最高为400 HV0.3,与钛/钢接头的硬度分布趋势一致;铜焊缝的硬度值较低,处于70 ~ 100 HV0.3;ER50-6焊缝的硬度处于100 ~ 220 HV0.3;T2和TA1母材硬度较低, T2平均硬度值约为40 HV0.3,TA1平均硬度值约为80 HV0.3.

    通过上述显微组织观察和显微硬度测试,发现钛/钢和钛/铜/钢异种金属焊缝中存在多种相组成(Fe-Ti,Cu-Ti等),这些相的种类、组成方式不同,由此导致的显微硬度也不同. 为了进一步确定焊缝中相组成与性能之间的对应关系,采用纳米压痕测试手段对上述钛/钢对接焊缝进行测试. 焊缝中典型区域的纳米压痕测试结果如图8所示,从图8(a)可以看出,在Cu-V焊缝中,铜基固溶体的硬度较低,为2.4 GPa,深色的Fe + Fe2Ti化合物硬度相对较高,为6.5 GPa;图8(b)为Cu-V/ERTi-1界面处的纳米压痕测试结果,随着Ti元素含量升高,铜基固溶体转变为Cu2Ti + Cu3Ti2化合物,硬度为9.2 GPa,部分区域生成了Fe2Ti金属间化合物,硬度较高,为20.7 GPa. 对比图7(a)中的显微硬度测试结果(Cu-V焊缝整体硬度较低,处于70 ~ 100 HV0.3),发现焊缝中硬度较高的Fe2Ti脆性相对焊缝整体硬度分布影响较小,这主要是由于这些脆性相尺寸小、分布弥散.

    图  8  钛/钢对接接头纳米压痕测试结果
    Figure  8.  Nanoindentation results of titanium/steel butt joints. (a) Cu-V weld; (b) the Cu-V/ERTi-1 interface region near Cu-V; (c) the Cu-V/ERTi-1 interface region near ERTi-1; (d) Cu-V/Q345 interface; (e) TA1/Cu-V/Q345 interface; (f) TA1/Q345 interface

    图8(c)是Cu-V焊缝与ERTi-1焊缝界面处组织,该处块状CuTi2 + FeTi化合物硬度为8.1 GPa,随着Ti元素含量升高,组织转变成CuTi2 + β-Ti,硬度略有降低,为7.8 GPa;图8(d)为Cu-V焊缝与Q345母材界面处形貌,该处区域靠近TA1/Q345界面处,母材α-Fe硬度较低(3.8 GPa),焊缝中β-Ti + CuTi2硬度高于母材,为10.9 GPa;图8(e)为Cu-V焊缝靠近TA1/Q345界面处的组织形貌,该处焊接时TA1和Q345同时熔化,形成了多种Fe-Ti和Cu-Ti化合物,其中FeTi硬度较高,为17.3 GPa,生成的Cu + Cu4Ti化合物硬度为8.5 GPa,呈现共晶形貌特征;图8(f)为进一步靠近TA1/Q345界面处的组织形貌,该处主要由块状的FeTi + β-Ti组织和其分布的基体组织(β-Ti + CuTi2)组成,块状FeTi + β-Ti的硬度为15.4 GPa,较基体组织β-Ti + CuTi2(10.9 GPa)硬度高.

    为了确定钛/钢、钛/铜/钢异质接头的整体强度,制备板状拉伸试样进行强度测试,测试结果显示钛/钢异质接头的抗拉强度为440 MPa,钛/铜/钢异质接头的抗拉强度为225 MPa,断裂位置均在焊缝区域.制备上述接头的拉伸断口试样,对其进行形貌观察,如图9图10所示.

    图  9  钛/钢对接接头拉伸断口形貌
    Figure  9.  Tensile fracture of titanium/steel butt joints. (a) Cu-V weld; (b) Cu-V/ERTi-1 interface; (c) ERTi-1 weld
    图  10  钛/铜/钢对接接头拉伸断口形貌
    Figure  10.  Tensile fracture of titanium/copper/steel butt joints. (a) Cu weld; (b) Cu/ERTi-1 interface; (c) ERTi-1 weld

    图9(a)为钛/钢对接接头中Cu-V焊缝处的断口形貌,该处断口呈现出脆性断裂特征,断口表面有颗粒状和短棒状形貌,结合EDS能谱结果,确定其主要为Fe + Fe2Ti混合物,对应的组织特征为图3(b)中谱图2区域. Cu-V/ERTi-1界面处的断口形貌如图9(b)所示,为解理形貌,该形貌对应的相组成为CuTi2 + FeTi混合相;图9(c)为ERTi-1焊缝区域的组织形貌,断口表面可以观察到韧窝形貌,该处区域虽然远离Cu-V/ERTi-1界面,但是该处依旧可以检测到Cu元素,相组成主要为β-Ti + CuTi2,这也验证Cu是强β-Ti形成元素[18]. ER50-6焊缝处的断口形貌以韧窝为主,这里不进行展示,采用Cu-V焊丝所得接头的断口形貌与采用Cu-Nb和Cu-V-Ag焊丝焊接的类似[17-18,20,22].

    图10(a)为钛/铜/钢对接接头中铜焊缝的断口形貌,主要以韧窝为主,说明铜焊缝韧性较好;图10(b)为Cu/ERTi-1界面处断口形貌,可以观察到众多小的解理台阶,相组成主要为CuTi2相;图10(c)为ERTi-1焊缝处的断口形貌,该处以细小的韧窝形貌为主,相组成主要为β-Ti + CuTi2,对应着图5(i)谱图7区域的组织.

    对于钛/钢复合板,当对其进行对接焊接时,由于钛板和钢板之间是通过爆炸焊接的方式直接连接,所以其对接接头中不可避免会出现局部钛和钢母材的熔化,这种现象即使采用高能束焊接方法(比如激光和电子束焊)也是无法避免的[21],所以钛/钢复合板对接接头中不可避免会有Fe-Ti脆性相的生成. Fe2Ti脆性相的硬度较高,当其尺寸较大时,将导致焊缝的直接开裂,相关研究结果在文献[11]中进行了系统报道.当优化过渡层焊接材料和焊接工艺时,比如采用文中的Cu-V焊丝,这些脆性的Fe-Ti金属间化合物中大部分可以被铜基固溶体所包围,焊后的接头不会出现裂纹,然而这种接头的拉伸断口是以脆性断裂形貌为主.为了解决这一问题,尝试采用铜为中间层制备钛/铜/钢三层复合板.当对钛/铜/钢三层复合板进行对接焊接时,由于铜中间层的加入,对接接头中Fe-Ti脆性相被彻底抑制.然而,根据Cu-Ti二元相图可知,两者可以生成多种Cu-Ti化合物,并且由于Cu是强β-Ti生成元素,导致铜在钛焊缝中的分布范围较广,对应的拉伸断口同样显示出了脆性断裂特征.即使阻断了Fe-Ti脆性相的产生,由此所生成的Cu-Ti化合物相,仍旧是接头的薄弱区域.因此,真正实现钛/钢复合板的高质量直接熔焊连接,仍是一个需要攻克的难题.

    (1)钛/钢接头显微结构观察显示,Cu-V焊缝以铜基固溶体和铁基固溶体为主,局部存在的Fe2Ti脆性相被韧性较好的铜基固溶体包围;Cu-V/ERTi-1界面处存在多种Cu-Ti和Fe-Ti金属间化合物;Cu-V焊缝与TA1/Q345界面处,存在Fe-Ti金属间化合物和CuTi2,FeTi,β-Ti化合物.

    (2)钛/铜/钢接头显微结构观察显示,Cu/ERTi-1焊缝界面处分布着多种Cu-Ti金属间化合物;Cu,ERT-1焊缝与TA1/T2界面处,分布着CuTi,Cu4Ti3和CuTi2化合物.与钛/钢对接接头相比,由于铜中间层的加入,钛/铜/钢对接焊缝中不再出现脆性的Fe-Ti相,但是Cu-Ti相的分布形式及规模与钛/钢复合板接头类似.

    (3)钛/钢复合板接头显微硬度结果显示,Cu-V/ERTi-1界面在ERTi-1一侧硬度较高,处于300 HV0.3以上;Cu-V焊缝整体硬度较低,处于70 ~ 100 HV0.3,Cu-V焊缝在靠近TA1/Q345复合板界面处硬度较高,局部高硬度点达到400 HV0.3.

    (4)钛/铜/钢复合板接头显微硬度结果显示,Cu/ERTi-1界面在ERTi-1一侧硬度较高,处于300 HV0.3以上,与钛/钢对接接头的硬度分布趋势一致;铜焊缝的硬度较低,处于70 ~ 100 HV0.3;ER50-6焊缝的硬度处于100 ~ 220 HV0.3.

    (5)纳米压痕测试结果确定了焊缝中典型相的硬度分布:Fe-Ti相硬度较高,Fe2Ti为20.7 GPa,FeTi为17.3 GPa,FeTi + β-Ti的硬度为15.4 GPa;Cu-Ti化合物硬度处于8 ~ 11 GPa之间.

    (6)钛/钢异质接头的抗拉强度为440 MPa,钛/铜/钢异质接头的抗拉强度为225 MPa,断裂位置均在焊缝区域,两者断口形貌中均出现韧窝和解理形貌.

  • 图  1   钛/钢复合板坡口形式及焊接顺序

    Figure  1.   Groove type and welding sequence of titanium/steel composite plate. (a) groove type; (b) welding sequence

    图  2   钛/铜/钢复合板坡口形式及焊接顺序

    Figure  2.   Groove type and welding sequence of titanium/copper/steel composite plate. (a) groove type; (b) welding sequence

    图  3   钛/钢复合板对接接头显微组织

    Figure  3.   Microstructure of titanium/steel butt joints. (a) ER50-6/Cu-V interface; (b) the central of Cu-V weld; (c) the phase map in the central of Cu-V weld; (d) Cu-V/ERTi-1 interface; (e) the high magnification image of Cu-V/ERTi-1 interface; (f) the phase map at Cu-V/ERTi-1 interface; (g) TA1/Cu-V/Q345 interface; (h) the high magnification image of TA1/Cu-V/Q345; (i) the phase map at TA1/Cu-V/Q345; (j) adjacent to Q345; (k) adjacent to TA1; (l) the phase map adjacent to Q345

    图  4   钛/钢复合板对接接头TEM结果

    Figure  4.   TEM results of titanium/steel butt joints. (a) ER50-6/Cu-V interface; (b) Cu-V weld; (c) the diffraction of A region; (d) TA1/Cu-V/Q345 region; (e) the diffraction of B region; (f) the diffraction of C region

    图  5   钛/铜/钢复合板对接接头显微组织

    Figure  5.   Microstructure of titanium/copper/steel butt joints. (a) ER50-6/Cu interface; (b) the high magnification image of ER50-6/Cu interface; (c) T2/Cu interface; (d) Cu/ERTi-1 interface; (e) the high magnification image of Cu/ERTi-1 interface; (f) ERTi-1 weld; (g) TA1/Cu/T2 interface; (h) the high magnification image of TA1/Cu/T2 interface; (i) the high magnification image of region near ERTi-1

    图  6   钛/铜/钢复合板对接接头TEM分析

    Figure  6.   TEM results of titanium/copper/steel butt joints. (a) the bright field image of Cu/ER50-6 interface; (b) the dark field image of Cu/ER50-6 interface; (c) the diffraction of A region; (d) Cu/ERTi-1 interface; (e) the high magnification image of Cu/ERTi-1 interface; (f) the diffraction of B region

    图  7   接头显微维氏硬度云图

    Figure  7.   Microhardness contours of butt joints. (a) titanium/steel butt joint; (b) titanium/copper/steel butt joint

    图  8   钛/钢对接接头纳米压痕测试结果

    Figure  8.   Nanoindentation results of titanium/steel butt joints. (a) Cu-V weld; (b) the Cu-V/ERTi-1 interface region near Cu-V; (c) the Cu-V/ERTi-1 interface region near ERTi-1; (d) Cu-V/Q345 interface; (e) TA1/Cu-V/Q345 interface; (f) TA1/Q345 interface

    图  9   钛/钢对接接头拉伸断口形貌

    Figure  9.   Tensile fracture of titanium/steel butt joints. (a) Cu-V weld; (b) Cu-V/ERTi-1 interface; (c) ERTi-1 weld

    图  10   钛/铜/钢对接接头拉伸断口形貌

    Figure  10.   Tensile fracture of titanium/copper/steel butt joints. (a) Cu weld; (b) Cu/ERTi-1 interface; (c) ERTi-1 weld

    表  1   焊接材料的主要化学成分(质量分数,%)

    Table  1   Main chemical composition of the welding materials

    焊丝CSiMnTiCuFeV
    ER50-60.080.891.51余量
    ERTi-10.03余量0.10
    ERCuSi-A3.01.0余量
    Cu-V0.010.300.50余量22.02
    下载: 导出CSV

    表  2   焊接工艺参数

    Table  2   Welding experiment paraments

    焊丝焊接方法焊接电流I/A电弧电压U/V焊接速度v/(cm·min−1)保护气体
    ER50-6MIG150 ~ 18020 ~ 246 ~ 780%Ar + 20%CO2
    ERTi-1TIG100 ~ 12020 ~ 223 ~ 4100%Ar
    ERCuSi-AMIG200 ~ 24020 ~ 246 ~ 7100%Ar
    Cu-V焊丝TIG140 ~ 16020 ~ 243 ~ 4100%Ar
    下载: 导出CSV

    表  3   钛/钢复合板对接接头典型区域EDS能谱(原子分数,%)

    Table  3   EDS results of the typical regions in titanium/steel butt joints

    区域FeCuVTi主要相组成
    谱图10.8095.603.60Cu
    谱图281.049.640.299.03Fe + Fe2Ti
    谱图366.535.222.5125.74Fe2Ti
    谱图411.1963.020.5025.29Cu2Ti + Cu3Ti2
    谱图525.7820.860.7152.64FeTi + β-Ti
    谱图69.7514.952.0973.21β-Ti + CuTi2
    谱图751.0719.214.0025.72Fe2Ti
    谱图828.5822.133.6845.61FeTi + Cu
    谱图910.5137.410.5951.48CuTi + FeTi
    谱图105.6030.200.8563.35CuTi2
    下载: 导出CSV

    表  4   钛/铜/钢复合板接头典型区域EDS能谱结果(原子分数,%)

    Table  4   EDS results of the typical regions in titanium/copper/steel butt joints

    区域FeCuSiTi主要相组成
    谱图10.1098.500.40Cu
    谱图287.7811.770.45α-Fe
    谱图352.1547.85CuTi
    谱图446.1753.83CuTi + CuTi2
    谱图532.7067.30CuTi2
    谱图653.1146.89CuTi + Cu4Ti3
    谱图712.9187.09β-Ti + CuTi2
    谱图822.8377.17CuTi2 + β-Ti
    下载: 导出CSV
  • [1] 杨培智, 张钧, 杨海欧. TC4钛合金混合制造技术的研究与进展[J]. 铸造技术, 2023, 44(11): 977 − 987.

    Yang Peizhi, Zhang Jun, Yang Haiou. Research and progress of the hybrid manufacturing of TC4 titanium alloy[J]. Foundry Technology, 2023, 44(11): 977 − 987.

    [2] 南榕, 蔡建华, 杨健, 等. 钛及钛合金腐蚀行为研究进展[J]. 钛工业进展, 2023, 40(5): 40 − 48.

    Nan Rong, Cai Jianhua, Yang Jian, et al. A review of corrosion resistance of titanium and titanium alloys[J]. Titanium Industry Progress, 2023, 40(5): 40 − 48.

    [3] 郑远谋. 爆炸焊接和金属复合材料及其工程应用[M]. 长沙: 中南大学出版社, 2002.

    Zheng Yuanmou. Explosive welding and metallic composite and their engineering application[M]. Changsha: Central South University Press, 2002.

    [4] 张保奇. 异种金属爆炸焊接结合界面的研究[D]. 大连: 大连理工大学, 2005.

    Zhang Baoqi. Investigation on bonding interface of explosive welding dissimilar metal[D]. Dalian: Dalian University of Technology, 2005.

    [5]

    Findik F. Recent developments in explosive welding[J]. Materials and Design, 2011, 32(3): 1081 − 1093. doi: 10.1016/j.matdes.2010.10.017

    [6] 张柯柯, 涂益民. 特种先进连接方法[M]. 哈尔滨: 哈尔滨工业大学出版社, 2012.

    Zhang Keke, Tu Yimin. Special advanced welding and joining technology[M]. Harbin: Harbin Institute of Technology Press, 2012.

    [7] 毕志雄, 李雪交, 吴勇, 等. 钛箔/钢爆炸焊接的界面结合性能[J]. 焊接学报, 2022, 43(4): 81 − 85.

    Bi Zhixiong, Li Xuejiao, Wu Yong, et al. Interfacial bonding properties of titanium foil/steel explosive welding[J]. Transactions of the China Welding Institution, 2022, 43(4): 81 − 85.

    [8] 张婷婷, 王文先, 袁晓丹, 等. Mg/Al 合金爆炸焊连接及其界面接合机制[J]. 机械工程学报, 2016, 52(12): 52 − 58. doi: 10.3901/JME.2016.12.052

    Zang Tingting, Wang Wenxian, Yuan Xiaodan, et al. Interface bonding mechanism of Mg/Al alloy explosive welded[J]. Journal of Mechanical Engineering, 2016, 52(12): 52 − 58. doi: 10.3901/JME.2016.12.052

    [9] 武通. 脉冲TIG焊接对钛/钢复合结构中爆炸焊界面影响研究[D]. 哈尔滨: 哈尔滨工业大学, 2021.

    Wu Tong. Research on the effect of pulse TIG welding on explosive welding interface in titanium/steel composite structure[D]. Harbin : Harbin Institute of Technology, 2021.

    [10]

    Kundu S, Ghosh M, Chatterjee S. Diffusion bonding of commercially pure titanium and 17-4 precipitation hardening stainless steel[J] Materials Science and Engineering A, 2006, 428: 18-23.

    [11]

    Li W, Yan L, Karnati S, et al. Ti-Fe intermetallics analysis and control in joining titanium alloy andstainless steel by laser metal deposition[J]. Journal of Materials Processing Technology, 2017, 242: 39 − 48. doi: 10.1016/j.jmatprotec.2016.11.010

    [12]

    Xia Y Q, Dong H G, Zhang R Z, et al. Interfacial microstructure and shear strength of Ti6Al4V alloy/316 L stainless steel joint brazed with Ti33.3Zr16.7Cu50- xNi x amorphous filler metals[J]. Materials and Design, 2020, 187: 108380. doi: 10.1016/j.matdes.2019.108380

    [13]

    Adomako N K, Kim J O, Lee S H, et al. Dissimilar welding between Ti-6Al-4V and 17-4PH stainless steel using a vanadium interlayer[J]. Materials Science and Engineering A, 2018, 732: 378 − 397. doi: 10.1016/j.msea.2018.07.015

    [14]

    Wang T, Zhang B G, Feng J C, et al. Effect of a copper filler metal on the microstructure and mechanical properties of electron beam welded titanium-stainless steel joint[J]. Materials Characterization, 2012, 73: 104 − 113. doi: 10.1016/j.matchar.2012.08.004

    [15]

    Wang T, Zhang B G, Chen G Q, et al. High strength electron beam welded titanium-steel joint with V/Cu based composite filler metals[J]. Vacuum, 2013, 94: 41 − 47. doi: 10.1016/j.vacuum.2013.01.015

    [16]

    Lee M K, Lee J G, Choi Y H, et al. Interlayer engineering for dissimilar bonding of titanium to stainless steel[J]. Materials Letters, 2010, 64: 1105 − 1108. doi: 10.1016/j.matlet.2010.02.024

    [17]

    Chu Q L, Tong X W, Xu S, et al. The formation of intermetallics in Ti/steel dissimilar joints welded by Cu-Nb composite filler[J]. Journal of Alloys and Compounds, 2020, 828: 154389. doi: 10.1016/j.jallcom.2020.154389

    [18]

    Chu Q L, Zhang M, Li J H, et al. Intermetallics in CP-Ti/X65 bimetallic sheets filled with Cu-based flux-cored wires[J]. Materials and Design, 2016, 90: 299 − 306. doi: 10.1016/j.matdes.2015.10.136

    [19]

    Chu Q L, Zhang M, Li J H, et al. Influence of vanadium filler on the properties of titanium and steel TIG welded joints[J]. Journal of Materials Processing Technology, 2017, 240: 293 − 304. doi: 10.1016/j.jmatprotec.2016.06.018

    [20]

    Chu Q L, Bai R X, Zhang M, et al. Microstructure and mechanical properties of titanium/steel bimetallic joints[J]. Materials Characterizaiton, 2017, 132: 330 − 337. doi: 10.1016/j.matchar.2017.08.025

    [21]

    Ning J, Zhang L J, Jiang G C, et al. Narrow gap multi-pass laser butt welding of explosion welded CP-Ti/Q235B bimetallic sheet by using a copper interlayer[J]. Journal of Alloy and Compounds, 2017, 701: 587 − 602. doi: 10.1016/j.jallcom.2017.01.129

    [22]

    Chu Q L, Xia T, Zhang L, et al. Structure-property correlation in weld metals and interface regions of titanium/steel dissimilar joints[J]. Journal of Materials Engineering and Performance, 2022, 31(8): 6509 − 6522. doi: 10.1007/s11665-022-06693-9

图(10)  /  表(4)
计量
  • 文章访问数:  100
  • HTML全文浏览量:  19
  • PDF下载量:  52
  • 被引次数: 0
出版历程
  • 收稿日期:  2024-08-25
  • 网络出版日期:  2024-11-28
  • 刊出日期:  2025-02-24

目录

/

返回文章
返回