Inconel718镍基合金与304不锈钢电子束焊接

Inconel 718镍基合金与304不锈钢电子束焊接李 宁1,2， 王 刚3， 王 廷1,2， 蒋思远1,2， 冯吉才1,2,3(1. 哈尔滨工业大学（威海） 先进焊接与连接国家重点实验室, 威海　264209；2. 哈尔滨工业大学（威海） 山东省特种焊接技术重点实验室, 威海　264209；3. 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)摘 要： 对Inconel 718镍基合金与304不锈钢进行了电子束焊接试验，分析了接头显微组织及力学性能. 结果表明，焊缝区中部由枝晶及细小的等轴晶组成，在近镍侧及近钢的熔合线，都由向焊缝中心方向生长的树枝晶组成.各特征区域显微硬度值各不相同，焊缝区高于镍基合金侧，高于不锈钢侧. 当焊接束流为8 mA ，焊接速度为700 mm/min 时，接头的抗拉强度最高为722 MPa . 拉伸试样断裂发生于焊缝区内部，呈典型的延性断裂，断口可观察到明显等轴状韧窝.关键词： 电子束焊接；镍基合金；不锈钢；微观组织；力学性能中图分类号：TG 456.3 文献标识码：A doi ：10.12073/j .hjxb .20194000470 序 言镍基高温合金具有优良的高温力学性能和耐腐蚀性能[1]，而不锈钢同样具有良好的热稳定性好，且材料成本较低[2]. 将不锈钢与镍基合金焊接制成双金属结构，可以同时发挥两种材料的优异性能，降低成本. 因此对于不锈钢与镍基合金焊接方法的研究也日益受到了人们的关注. 有学者分别研究了镍基合金和不锈钢的钨极氩弧焊、激光焊及搅拌摩擦焊[3-5]. 真空电子束焊接热输入小、焊接变形小、焊缝纯洁度高、焊接参数再现性高，更适合于异种金属的焊接[6]. Ramkumar 等人[7]研究了Inconel 625镍基合金和UNS 32205不锈钢的连接，焊缝区富Mo 相在枝晶间析出，镍侧热影响区无明显的晶粒粗化及第二相析出. 试样拉伸断裂发生在焊缝区域，最高抗拉强度达到850 MPa . Christopher 等人[8]进行了625镍基合金与9%Cr 钢的真空电子束焊接工艺试验. 结果表明焊接接头在625 ℃产生蠕变，应力水平在100 ~ 156 MPa 之间，蠕变断裂发生在钢侧热影响区.通过对Inconel 718镍基合金与304不锈钢电子束焊接特性进行分析，揭示两种合金在电子束焊接后组织与性能变化，为镍/钢异种金属接头的工程应用提供试验基础.1 试验方法试验材料为304不锈钢和Inconel 718镍基合金薄板，母材成分如表1和表2所示. 试验前采用电火花线切割成51 mm × 26 mm × 1.6 mm 试板，使用超声波丙酮清洗备用. 焊接参数为：真空度4 ×10−2Pa ，加速电压70 kV ，电子束流8 mA ，焊接速度700 mm/min ，表面聚焦.表 1 304不锈钢的化学成分(质量分数，%)Table 1 Chemical compositions of SUS304C Si Mn Cr Ni S P Fe0.071.02.017.0 ~ 19.08.0 ~ 11.00.030.035余量表 2 Inconel 718镍基合金的化学成分(质量分数，%)Table 2 Chemical compositions of Inconel 718Ni Cr Fe Nb Mo Ti Al Co50 ~ 5517 ~ 211.04.75 ~ 5.52.8 ~ 3.30.65 ~ 1.150.2 ~ 0.81.0沿焊缝垂直方向截取同时包含母材、焊缝以及热影响区的金相试样. 经过打磨、抛光至试样表面在光学显微镜下无明显划痕. 抛光后使用酒精冲洗，用新配制的10%草酸溶液进行电解腐蚀，腐蚀时间5 s . 采用日本OLYMPUS 光学显微镜以及MERLIN Compact 扫描电子显微镜(SEM)观察微收稿日期：2018 − 07 − 05基金项目：国家自然科学基金航天先进制造技术研究联合基金(U1637104)；山东省重点研发计划(2017GGX30110)第 40 卷 第 2 期2019 年 2 月焊 接 学 报TRANSACTIONS OF THE CHINA WELDING INSTITUTIONVol .40(2):082 − 085February 2019观组织及断口形貌，分析接头组织成分. 采用HV-1000-T 标准显微硬度计测试焊接接头金相试样显微硬度，载荷50 g ，加载时间10 s . 使用Instron5967型万能材料试验机测试接头抗拉强度，进行三组拉伸试验取平均值.2 试验结果及讨论2.1 微观组织接头横截面宏观形貌如图1所示，焊缝整体呈现“钉子形”. 但因718镍基合金熔点、热导率及比热容均低于304不锈钢母材，在电子束热源的作用下镍基合金母材熔化量相对较多，使得焊缝形貌呈现左右不对称现象.从图1中还可以明显发现，焊缝两侧组织分布存在一定的不均匀性. 依附于不锈钢侧生长的枝晶延续到焊缝中部，而镍基合金侧枝晶分布较为分散. 熔池凝固过程中两侧过冷度不同影响了焊缝内部组织形貌.HAZWZ718 镍基合金硬度及线扫位置304 不锈钢500 μm图 1 接头横截面宏观形貌Fig. 1 Cross section of joint根据显微组织特征的不同，接头横截面分为母材(BM)、焊缝区(WZ)、熔合区(FZ)和热影响区(HAZ)，分别对不同区域显微组织进行光学显微观察，如图2所示.718 镍基合金(b) 镍基合金侧热影响区杂质相50 μm50 μm(a) Inconel 718 镍基合金母材304 不锈钢50 μm(d) 不锈钢侧热影响区50 μm (c) 焊缝区图 2 典型区域微观组织Fig. 2 Macrostructure of typical region of the joinInconel 718镍基合金母材由明显的奥氏体晶粒构成，晶粒及晶界处弥散分布着如图2a 所示的杂质相. 经过电子束焊接热循环之后，镍基合金侧热影响区组织发生再结晶、晶粒长大，熔合区柱状晶与热影响区再结晶晶粒联生生长，柱状晶生长方向垂直于熔合线方向. 不锈钢侧熔合线两侧焊缝及母材分界清晰，熔合线附近枝晶依附熔合线向焊缝中心方向生长；焊缝区域内部及焊缝上部分布着一次和二次树枝晶及部分等轴晶.进一步分析焊缝组织，对接头内元素进行了线第 2 期李 宁，等：Inconel 718镍基合金与304不锈钢电子束焊接83扫描分析，结果如图3所示. 由图3可以发现，由于电子束焊接熔池的流动及Fe-Ni 之间较大的固溶度，使得Fe 元素和Ni 元素含量在焊缝中整体均匀分布，Fe 元素和Ni 元素含量相比不锈钢和镍基合金母材有明显降低，靠近镍侧焊缝区Ni 元素略高于Fe 元素，在焊缝中心和近不锈钢侧焊缝内Fe 元素含量略高于Ni 元素.5001 000 1 50020406080100 Cr Ni Fe 距离 d /μm元素含量 w (%)718 镍基合金304 不锈钢图 3 元素线扫描结果Fig. 3 Line scanning results焊缝区微观组织如图4所示，不同特征组织能谱分析结果如表3所示. 焊缝组织主要由Fe-Ni 基树枝晶组成，枝晶间有断续的富Nb 相析出.Silva 等人[9]的研究发现镍基合金焊缝在凝固过程中，Laves 相和复合碳化物(NbTi)C 组成的二次相会以氮化钛为核心析出. Aghajani 等人[10]也认为氮化钛在镍基合金焊缝凝固过程中，是M23C6碳化物或Laves 相等二次相的形核核心. 富Nb 相的析出形成网状增强相，对接头力学性能具有一定增强作用.2.2 焊接接头的力学性能2.2.1 抗拉强度与断口形貌母材和接头的抗拉强度如表4所示. 从表中的结果可以看出，接头的抗强度接近304不锈钢母材的强度，达到96%. 说明采用电子束焊接方法可以很好地实现718镍基合金和304不锈钢的连接. 同时焊接接头保留了母材具有的一定塑性，提高了接头的综合力学性能. 在焊缝区组织以Fe 基或Ni 基固溶体为主，未观察到的连续分布的脆性相生成，保证了接头的连接强度和韧性.拉伸试样的断裂位置及断口形貌如图5所示.表 4 母材及焊接接头抗拉强度Table 4 Mechanical properties of matrix and weldingjoint材料抗拉强度R m /MPa断后伸长率A (%)Inconel 718镍基合金96530304不锈钢752⩾40焊接接头72215表 3 图4中典型位置化学成分(原子分数, %)Table 3 Chemical compositions of typical positions inFig. 4位置Nb Cr Fe Ni A 020.6245.8833.50B8.8218.9035.8036.47AB10 μm图 4 焊缝微观组织形貌Fig. 4 Microstructure morphology718 镍基合金304 不锈钢500 μm50 μm(a) 拉伸件宏观断裂(b) 拉伸断裂位置微观形貌(c) 拉伸断口形貌图 5 焊接接头断口形貌及断裂位置Fig. 5 Tensile fractography and fracture position84焊 接 学 报第 40 卷图5b 表明焊件拉伸试样均断裂在焊缝区，为韧性剪切断裂，焊缝存在明显的塑性变形.由图5c 所示，断口可观察到明显韧窝. 接头受外拉应力过程中，枝晶间富Nb 的第二相与基体分离，由于焊接接头的塑性较好，会在第二相质点处发生应力集中，并在外加应力的作用下，基体与第二相质点发生分裂形成孔洞，并使位错塞集的大部分进入孔洞，使孔洞不断长大，最终以颈缩的方式断开而使微孔联通，造成失效.2.2.2 显微硬度分析截面水平方向进行显微硬度测试，结果如图6所示. 焊缝沿水平方向，焊缝区域硬度值较均匀分布在295 ~ 322 HV 之间；镍基合金侧硬度值分布在280 ~ 300 HV 之间，略低于焊缝硬度；不锈钢侧母材硬度较低，分布在225 ~ 255 HV 之间. 可以发现焊缝区域硬度明显高于两侧的Inconel 718镍基合金和304不锈钢母材. 焊缝中网状分布的富Nb 二次相对于接头硬度提高起到了一定作用. 焊缝内Ni 元素含量较高的镍基合金侧硬度高于Fe 元素含量略高的焊缝中部及不锈钢侧.−1.0−0.500.5 1.0220240260280300320340距离焊缝中心距离 s /mm显微硬度 H (H V )718 镍基合金304 不锈钢图 6 焊缝水平方向显微硬度Fig. 6 Horizontal distribution of microhardness of thewelded joint3 结 论(1) 通过电子束焊接可以获得Inconel 718镍基高温合金与304不锈钢成功连接、无缺陷的焊接接头，接头强度达到最高722 MPa ，达到不锈钢母材的96%.(2) 镍/钢电子束焊缝组织主要由Ni 基和Fe 基枝晶组成，枝晶间有富Nb 相析出.(3) 拉伸试样断裂发生于焊缝区内部，呈典型的延性断裂，断口可观察到明显等轴状韧窝.(4) 焊缝区域硬度高于两侧母材，Ni 元素含量较高的区域硬度高于Fe 元素含量较高的焊缝区域.参考文献：吴　冰, 李晋炜, 毛智勇, 等. 镍基高温合金电子束焊接接头疲劳性能[J]. 焊接学报, 2013, 34(8): 109 − 112.Wu Bing, Li Jinwei, Mao Zhiyong, et al . Fatigue properties of electron beam welded joints of Nickelbase superalloy[J]. Transac-tions of the China Welding Institution, 2013, 34(8): 109 − 112.[1]张志强, 荆洪阳, 徐连勇, 等. 双相不锈钢多层多道焊接接头微观组织表征[J]. 焊接学报, 2017, 38(5): 79 − 82.Zhang Zhiqiang, Jing Hongyang, Xu Lianyong, et al . Microstruc-ture characterization of duplex stainless steel multi-pass welded joint[J]. Transactions of the China Welding Institution, 2017,38(5): 79 − 82.[2]Kangazian J, Shamanian M, Ashrafi A. Dissimilar weldingbetween SAF 2507 stainless steel and Incoloy 825 Ni-based alloy:the role of microstructure on corrosion behavior of the weld met-als[J]. Journal of Manufacturing Processes, 2017, 29: 376 − 388.[3]Chen J, Khalifa A, Xue L, et al . Laser weldability of Zr-2.5Nb al-loy to AISI 410 stainless steel with Ni filler[J]. Journal of Materi-als Processing Technology, 2018, 255: 184 − 194.[4]Rodriguez J, Ramirez A J. Microstructural characterisation of fric-tion stir welding joints of mild steel to Ni-based alloy 625[J]. Ma-terials Characterization, 2015, 110: 126 − 135.[5]冯吉才, 王　廷, 张秉刚, 等. 异种材料真空电子束焊接研究现状分析[J]. 焊接学报, 2009, 30(10): 108 − 112.Feng Jicai, Wang Ting, Zhang Binggang, et al . Research status analysis of electron beam welding for joining of dissimilar materi-als[J]. Transactions of the China Welding Institution, 2009,30(10): 108 − 112.[6]Ramkumar K D, Sridhar R, Periwal S, et al . Investigations on thestructure – property relationships of electron beam welded Incon-el 625 and UNS 32205[J]. Materials & Design, 2015, 68: 158 − 166.[7]Wiednig C, Lochbichler C, Enzinger N, et al . Dissimilar electronbeam welding of nickel base alloy 625 and 9% Cr steel[J]. Pro-cedia Engineering, 2014, 86: 184 − 194.[8]Silva C C, Miranda H C D, Motta M F, et al . New insight on thesolidification path of an alloy 625 weld overlay[J]. Journal of Ma-terials Research & Technology, 2013, 2(3): 228 − 237.[9]Aghajani A, Tewes J, Parsa A B, et al . Identification of Mo-RichM23C6, Carbides in Alloy 718[J]. Metallurgical & Materials Transactions A, 2016, 47(9): 4382 − 4392.[10]第一作者简介：李　宁，男，1995年出生，硕士研究生.主要从事于电子束焊接工艺方面的研究. 发表论文1篇. Email:771790741@qq .com通信作者简介：王　廷，男，副教授. Email: fgwangting@第 2 期李 宁，等：Inconel 718镍基合金与304不锈钢电子束焊接85Cu interlayer. There are obvious indentations on the surface of NiTi welding due to the effect of sonotrode tip. Well bonding could be observed at the weld interface, and no intermetallic compound was formed. Ultrasonic welding NiTi shape memory alloy showed a reversible phase transition process. The strength of NiTi memory alloy joints reached 65% of the base material, and the fracture surface showed ductile fracture characteristic. Ultrasonic welding method conlat solve the problem of brittle intermetallic compounds produced by traditional fusion welding method, which provides a new solution for the connection of NiTi shape memory alloys.Key words: shape memory alloy；ultrasonic welding；weld morphology；mechanical propertiesAnalysis of beam scattering and weld morphology in helium protected by ultra-low vacuum electron beam welding CHEN Jian， LENG Bing， ZHENG Hong， SU Jinhua (Harbin Welding Institute Limited Company, Harbin 150028, China). pp 68-72Abstract:In order to solve the problems of melting depth and melting width reduction, and unstable welding process caused by severe scattering of electron beam in low vacuum and local vacuum electron beam welding. The variation of electron beam and weld morphology with the acceleration voltage of 100 kV, beam current of 60 mA and vacuum of 133.32 ~ 1 333.2 Pa was studied. A coaxial helium shielded welding process is proposed. During the welding of low carbon steel, the whole process is stable. The weld penetration is 30 ~ 40 mm, and the electron beam welding joint with large aspect ratio is obtained.Key words: electron beam；beam scattering；ultra-low vacuum；helium protectionEffect of surfactant on TC4 sheet with back reflection induced synergistic laser welding WANG Hongyu1，DING Rui1， CHAO Shuan2， LI Le1 (1. School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China；2. Agricultural Mechanical Technology Promotion Station of Zhenjiang, Zhenjiang 212013, China). pp 73-76Abstract: In order to explore the way to reduce energy threshold in X-shape welding formation of TC4 sheet, the influence of surfactant type, coating thickness and coating position on back reflection induced synergistic laser welding was systematically analyzed in this paper. The results show that the effect of different kinds of surfactant were different. Among them, coating NaCl and NaF is conducive to the formation of back reflection plume effects, while coating TiO2 has some weak effect. At the same time, the back reflection plume effect was further enhanced the increase of the surfactant coating thickness NaF was more sensitive to the coating thickness than NaCl. In addition, there is little effect when coating surfactant on the back of weld. It is concluded that the effect of surfactant on the back reflection induced synergistic laser welding of TC4 sheet is mainly due to the gain of laser energy absorption.Key words: titanium alloy sheet；laser welding；back reflection plume effect；surfactant；welding appearanceRecognition of weld seam for tailored blank laser welding based on least square support vector machine ZOU Yuanyuan1,2， ZUO Kezhu1,2， FANG Lingshen3， LI Pengfei1,2 (1. School of Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China；2. National-Local Joint Engineering Laboratory of NC Machining Equipment and Technology of High-Grade Stone, Shenyang 110168, China；3. Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China). pp 77-81Abstract: Accurate recognition of weld seam was the key for structural-light visual inspection of weld quality with high precision in tailored blank laser welding. Because of the problem that when the distortion of laser stripe was not obvious in the image and the welding seam cannot be recognized accurately, a recognition method according to the texture information of weld seam based on least squares support vector machine was proposed in this paper. Firstly, the textural features of the image were analysed and the textural features which had obvious difference between weld seam region and non-welded region were extracted. Secondly, the least square support vector machine model was trained and the coarse recognition of weld seam was accomplished. Finally, a fine recognition was achieved by Laws texture filter and threshold segmentation. The recognition experiments were carried out for weld seam in different welding parameters and the results showed that the weld seam can be recognized effectively by this method.Key words: weld seam recognition；image segmenta-tion；least square support vector machine；tailored blank laser weldingWeldability of Inconel 718 and 304 stainless steel by electron beam welding LI Ning1,2， WANG Gang3，WANG Ting1,2， JIANG Siyuan1,2， FEN Jicai1,2,3 (1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology at Weihai, Weihai 264209, China；2. Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China；3. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China). pp 82-85Abstract:The electron beam welding test of Inconel 718 nickel-based superalloy and 304 stainless steel was carried out, and the microstructure and mechanical properties of the joint were analyzed. The results show that the middle of the weld zone is composed of fine equiaxed grains, and in the near-nickel side and near-steel fusion lines, there are some growth directions. The hardness of the joints is different among WZ 304 stainless and Inconel 718 and the handless of WZ is higher than that of Inconel 718 and 304 stainless steel. When the welding beam is 8 mA and the welding speed is 700 mm/min, the tensile strength of the joint is 722 MPa. Tensile studies showed that the fracture occurred at the weld zone. TheIV TRANSACTIONS OF THE CHINA WELDING INSTITUTION2019, Vol. 40, No. 2fracture featured a typical ductile fracture, consisting of the dimple of the isoaxial shape.Key words: electron beam welding；Ni-based alloy；stainless steel；microstructures；mechanical properties Microstructure and property of laser welded joint with high frequency micro-vibration process ZHANG Cheng1， LU Qinghua1,2， CAI Zunwu1， ZHANG Peilei1,2 (1. School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China；2. Shanghai High Strength Laser Intelligent Processing Equipment Key Technology Research and Development Center , Shanghai 201620, China). pp 86-90Abstract:Based on high frequency micro-vibration platform, the 316L stainless steel was welded by laser welding with vibration. The microstructure and property of laser welded joint with high frequency micro-vibration process had been investigated. The results indicate that good welding surface could be got under vibration. No spatters could be found. No collapse and excess weld metal existed. Weld width form uniformly in the back weld. Grain refinement is related to resonant vibration frequency during solidification in the weld. The smallest grain size and the most conspicuous grain refinement were obtained at the resonant frequency of 1 467.5 Hz. In addition, the particles spreaded and dispersed between the austenite grains. The new phase and the large particles were reduced with vibration. With the increase of the vibration frequency, weld microhardness increased, especially with the higher resonance frequency. At the resonant frequency of 1 467.5 Hz, vibration acceleration of 160 m/s2, the average microhardness value of weld is 206 HV, which was increased by 5.6% compared with that with no vibration condition.Key words: high-frequency micro-vibration；laser welding；grain refinement；microhardnessCharacteristics of tensile process in double-sided laser beam welded T-joints of Ti-6Al-4V alloy MA Xuyi，DUAN Aiqin， LU Wei， YANG Jing (Science and Technology on Power Beam Processes Laboratory, AVIC Manufacturing Technology Institute, Beijing 100024, China). pp 91-97Abstract: T-joints of Ti-6Al-4V alloy were fabricated by double-sided synchronized laser beam welding with homologous filler wire. The influence and characteristics of the weld defects such as undercut, lack of fusion, and porosity defects during tensile process were investigated by the method of infrared thermal imaging. Results show that the temperature increased at the base metal on both sides of the skin. The stress concentration of T-joint was obvious with the increasing of deformation. The temperature and plastic deformation increased at the zone of stress concentration where the fracture occurred finally. The lack of fusion and porosity defects were located at center position of the hardening zone, the influence of strengthening effect for welded T-joint had little change. The temperature increased in base metal on one side of the skin because of plastic deformation, and the fracture occurred in base metal at the peak temperature.Key words: Ti-6Al-4V alloy；double-sided laser beam welding；infrared thermal imaging；tensile process；weld defect Microstructure and hardness of W alloy on 45 steel by electron beam scanning WEI Deqiang， REN Xulong，WANG Rong， LV Shaopeng (Guilin University of Electronic Technology, Teaching Practice Department, Guilin 541004, China). pp 98-103Abstract:The microstructure and properties of iron and steel materials can be improved by electron beam scanning surface alloying. In this paper, the surface of 45 steel is treated by cladding alloy by plasma spraying technology and electron beam scanning technique. The effect of electron beam scanning on the strengthened layer was investigated. The results show that 45 steel treated by surface alloying, the surface can be divided into alloying zone, heat affected zone and the base zone. The microstructure of the alloying zone was acicular martensite and tungsten carbide particles, the microhardness is 1 250 HV, which was 5 times of the substrate; the microstructure of the heat affected zone is acicular martensite and ferrite. The microhardness was 860 HV, which was 3 times of the substrate. The microstructure of the substrate was pearlite and ferrite. The technological parameters of the electron beam had great influence on microstructure and hardness of the strengthened layer. The thickness of the strengthened layer increased with the increase of the beam power, and decreased with the increase of the scanning speed.Key words: electron beam scanning；alloying；45 steel；microstructure；hardnessTracking algorithm for solid-liquid separation point of molten pool tail in GTAW-based additive manufacturing PI Yupeng1， XIONG Jun1， ZHAO Huihui2， CHEN Hui1 (1. Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610036, China；2. Shanghai Aerospace Equipments Manufacturer Co., Ltd., Shanghai 200245, China). pp 104-109Abstract:This study aims at the solid-liquid separation point detection of molten pool tail in GTAW-based additive manufacturing. Based on characteristics of a large fluctuation of molten pool edge and a small fluctuation of solidified metal edge, a tracking algorithm for solid-liquid separation point of molten pool tail was proposed through continuous image acquisition. The image preprocessing including denoising, Gaussian filtering, edge detection and threshold segmentation was performed on molten pool tail image. The coefficient of variation was calculated according to the pixels coordinates, and the pixel coefficient of variation curve was fitted by the polynomial function. Then, the first-order derivative of the curve was obtained, and the coefficient of variation curve break point was determined to define the solid-liquid separation point. The results show that the2019, Vol. 40, No. 2TRANSACTIONS OF THE CHINA WELDING INSTITUTION V。