共查询到17条相似文献,搜索用时 62 毫秒
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分别利用直流冷金属过渡(CMT)和变极性CMT脉冲复合技术进行TC4和ER2319焊丝的堆积,实现钛/铝异种金属丝材+电弧增材制造,通过高速摄像及电信号采集系统进行电弧形态、熔滴过渡以及电流/电压信号的采集分析;利用OM、SEM、TEM、EDS、硬度实验以及拉伸实验等方法对钛/铝异种金属构件的微观组织与力学性能进行分析。结果表明,变极性CMT脉冲复合堆积铝合金过程包括正极性脉冲阶段和负极性CMT阶段。在正极性脉冲阶段,电弧集中且热输入较大;在变极性CMT阶段,热输入较小且对构件具有明显的冷却效果。钛/铝异种金属构件的反应层包括过渡层和界面层,Ti Al3界面层的厚度约为10μm。在界面层存在微裂纹;反应层的硬度介于钛合金和铝合金之间;钛/铝异种金属构件的平均抗拉强度为65 MPa,所有拉伸试样均在界面层断裂,断裂方式均具有脆性断裂的特征。 相似文献
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以ER4043的铝焊丝对6061铝合金和TA2纯钛进行CMT熔钎焊,采用金相显微镜、扫描电镜(SEM)和能谱分析仪(EDS)分析了焊接接头的微观组织特征,并通过拉伸试验对接头进行了力学性能的评定. 结果表明,焊接接头具有熔焊和钎焊双重性质:铝母材局部熔化,与熔化的焊丝金属混合后凝固形成焊缝;而没有熔化的钛母材通过Ti原子的扩散与焊缝金属形成金属间化合物结合层的钎焊界面. 钎焊界面处反应层可分为靠近钛板一侧的连续层Ti3Al和向焊缝内部生长的锯齿状的反应层TiAl3. 当钛板坡口角度为30°时,钎焊界面化合物生长均匀良好,接头会断裂在铝母材的热影响区,最高抗拉强度达到197.5 MPa. 相似文献
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利用ABAQUS有限元软件建立镁/钛异种金属搭接接头的有限元模型,对镁/钛异种金属冷金属过渡焊接过程的温度场进行模拟,分析温度场的变化规律,并通过试验验证模拟结果的准确性.比较了不同送丝速度下温度场的变化规律,并对特征点的显微组织进行比较.结果表明,镁、钛两侧的温度场呈不对称分布.距离焊缝中心相同的两点,镁板侧试件温度上升较快,达到的峰值温度比钛板侧高,且下降速度也快.随着送丝速度的增加,峰值温度变高,达到钛板的熔化温度,钛的熔化量也就随之增加,镁钛连接界面有较好的结合. 相似文献
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钛合金高强度、高耐热的特性决定了其在航空航天、船舶制造等领域的广泛应用,但由于钛合金的难加工性,使得传统锻造+机加的方式模具损耗严重、制造周期长。增材制造作为一种制造成本低、成形效率高的绿色化制造工艺,凭借其无需模具、直接成形的优势在钛合金制造领域受到国内外学者的广泛关注。电弧增材制造技术相较于其他增材工艺(如激光增材制造、电子束增材制造等)沉积效率更高,不受零件尺寸的限制,在大型和超大型结构件的制造中具有突出优势,其中基于冷金属过渡(Cold metal transfer,CMT)的电弧增材制造技术由于沉积过程更稳定、热输入量更低,已逐渐成为钛合金增材制造领域的研究热点。文中对基于冷金属过渡的钛合金电弧增材制造技术的研究现状进行综述,介绍钛合金打印件的微观组织和力学性能特征,总结分析了成形参数对打印件微观组织与力学性能的影响规律,并概述了形核条件调控、轧制和超声冲击等辅助技术对打印件微观组织与力学性能的影响机制,最后展望了钛合金CMT电弧增材制造的未来发展趋势。 相似文献
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激光增材制造技术具有柔性化程度高、适应性强、材料利用率高、近净成形等特点,被广泛的应用于兼具功能和结构作用的多孔金属的制备。多孔金属激光增材制造技术按孔形成机制的不同可分为直接成孔法、添加造孔剂法以及结构设计成孔法。在介绍多孔金属激光增材制造国内外研究现状的基础上,指出各制备工艺的特点,并展望了多孔金属激光增材制造技术的发展趋势。 相似文献
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采用冷金属过渡的方法对AZ31B变形镁合金和镀锌钢板进行搭接点焊试验,运用正交试验法优化工艺参数,同时利用光学显微镜、扫描电镜和万能拉伸试验机对焊接接头的微观组织和力学性能进行研究.结果表明,运用冷金属过渡方法能够获得成形美观和性能良好的焊接接头;工艺参数显著性顺序为镀锌钢板孔径大小、送丝速度、点焊时间;接头为典型的点熔钎焊接头,由钎焊结合区和熔焊结合区组成;接头的抗拉剪载荷可达3.12 kN,远大于相同尺寸下镁镁点焊试样的抗拉剪载荷,接头的断裂方式为剪切型断裂和撕裂型断裂. 相似文献
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A. Gomez Ortega L. Corona Galvan B. Mezrag S. Rouquette 《Science & Technology of Welding & Joining》2018,23(4):316-332
A 3D print device using a cold metal transfer arc welding station to melt a metallic filler wire is developed to build aluminium part by optimising the process parameters. First tests achieved using standard pre-recorded process parameters allow to study the effect of the travel speed and the average welding power on the geometrical characteristics of mono-layer deposits and on walls built by layers superposition. Finally, a parametric study of the effect of each process parameter controlling the shape of the arc current or voltage and the filler wire feeding is carried out in order to try to improve the geometrical regularity of the deposits, and to better understand the effect of each parameter on the melting of the filler wire, its transfer on the support plate, and the geometry of the formed bead. 相似文献
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Mg/Al dissimilar butt joint was produced by modified cold metal transfer process using wire AZ31 as filler metal. The energy input characteristics and the microstructure and mechanical behaviour of the joint were investigated. Microstructural analysis shows that a diffusion Mg–Al intermetallic compounds interface layer formed along the weld boundary near Al substrate. The interface layer consisted of three intermediate layers from Al substrate to weld metal: Mg2Al3 layer, Mg17Al12 layer and Mg17Al12?+?α-Mg solid solution eutectic layer. The tensile strength of the welded joint was 38.4?MPa, which was fairly dependent on the lowest strength of the three intermediate layers. The brittle fracture occurred primarily within the thinnest Mg2Al3 intermediate layer adjacent to Al substrate. 相似文献
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基于钨极氩弧焊的电弧增材制造(GT-WAAM)工艺,以6 mm厚Ti6Al4V合金为基板,直径1.2 mm的Ti6Al4V焊丝为材料,利用CO2进行层间冷却,得到成形均匀的沉积结构。通过对焊接过程热循环特点、沉积形貌、硬度分布及力学性能分析,获得沉积结构质量评价。结果表明,提高冷却速率可以细化沉积结构晶粒,得到针状的α′相,从而改善材料的硬度和抗拉强度;在沉积结构中,堆积高度增加产生的热积累效应,使冷却气体中的C和O元素存在与堆积金属发生潜在的化学反应的可能。采用层间冷却控制层间温度能有效改善沉积结构质量,可使制造效率提高80%以上。
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In the context of additive manufacturing processes, the influence of specimen deformation from different welding paths is conducted by using CMT-AM. A least-squares method was used to quantitatively measure specimen deformation. The values of S (i.e., the sum of the distance from each feature point in a plane to the ideal plane)from different welding paths had significant influence on deformation of deposited layer.With the value of S increasing, the deformation of deposited layer gradually increased. With this result, a suitable welding trace plan was ascertained, which was successfully used to acquire well-formed and densely organized specimens during the arc-welding additive manufacturing process. Our results provide a foundation for experiments based on deposited layer scanning trace planning. 相似文献
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《中国有色金属学会会刊》2021,31(12):3739-3751
The electrochemical dissolution and passivation of laser additive manufactured Ti6Al4V were investigated through Tafel polarization, potentiostatic polarization and AC impedance measurements. The results show that the solution treatment−aging (STA) process aggravates the element micro-segregation compared to the annealing process, leading to varied Al and V contents of the phases from different samples. It is proven that either Al-rich or V-rich condition can highly affect the electrochemical dissolution behaviors due to thermodynamical instability caused by element segregation. The dissolution rate in the metastable passivation process is controlled by the stability of the produced film that is affected by phases distribution, especially the difficult-to-dissolve phase. And then, the dissolution rate of the phases in the transpassivation region is consistent with the rank in the activation process because the dense film is not capable of being produced. Compared to the annealed sample, the higher dissolution rate of the STA sample is beneficial to the electrochemical machining (ECM) of Ti6Al4V. 相似文献
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以2 mm厚Q235镀锌钢板为基板,直径1.2 mm的4043铝合金焊丝为增材材料,利用BC-MIG焊工艺进行增材试验,得到了成形美观,性能优良的T型材结构. 采用金相显微镜、显微硬度仪、万能拉伸试验机对接头的组织形貌、硬度分布、剪切性能进行研究,获得了沉积层的组织和力学性能的变化规律. 结果表明,沉积层最底部靠铝一侧和靠钢一侧分别形成细长针状和带状Fe/Al化合物,沉积层中部由向上生长的树枝晶组成,而在沉积层顶部的组织没有定向生长的趋势. 剪切试验表明,铝/钢异种金属T型材最大可承受2 108 N的剪切力,剪切角达到13.5°时,受力一侧堆焊层根部发生断裂,堆焊层上无明显裂纹. 相似文献