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材料为ZG310-570的铸钢件因承受冲击载荷的频繁作用导致其内孔磨损失效,是该类铸钢件最主要的失效形式。利用粉末等离子弧喷焊技术对铸钢件受损内孔进行修复,并利用火花直读光谱仪、金相显微镜、布氏硬度计、冲击试验机和扫描电子显微镜分别对喷焊层外观质量、显微组织和力学性能进行分析。分析结果表明,采用粉末等离子弧喷焊修复方法使铸钢件内孔尺寸得到恢复;喷焊层与基体为冶金结合,结合线清晰;喷焊层的硬度值为267.5 HBW,优于基体材料的180.2 HBW,修复后的内孔冲击吸收功为15.40 J,满足技术要求;喷焊层的断口存在大量撕裂,说明喷焊层具有一定的冲击韧性。 相似文献
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According to the strategy of controlled pulse key-holing, a new sensing and control system was developed for monitoring and controlling the keyhole condition during plasma arc welding (PAW). Through sensing and processing the efflux plasma voltage signals, the quantitative relationship among the welding current, efflux plasma voltage and backside weld width of the weld was established. PAW experiments show that the efflux plasma voltage can reflect the state of keyhole and backside weld width accurately. The closed-loop control tests validate the stability and reliability of the developed keyhole PAW system. 相似文献
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硅钢片是变压器铁芯的主要原材料,在变压器铁芯加工过程中,难免有部分原材料在尺寸上不能满足要求,只能做废品处理,造成大量浪费。本文论述了微束等离子弧焊接的特点,介绍了一种硅钢片微束等离子弧焊接工艺,并通过试验得出了常用硅钢片的合理焊接工艺参数。实践证明,硅钢片经过焊接以后,可以继续使用,为企业节约了原材料,降低了加工成本。 相似文献
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分析了脉冲电弧焊技术在铝合金及薄板、异种材料连接、不锈钢、镁合金的最新应用,研究了脉冲占空比、脉冲电流和基值电流、脉冲频率等参数对焊接工艺性能的影响,并指出脉冲焊技术应实现一脉一滴的熔滴过渡,建立各参数之间对应的函数关系,才能为发展自动化脉冲焊接设备提供可靠的技术支持。 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):362-368
AbstractPulsing of the welding current is one approach for refining the fusion zone microstructure in materials joined by fusion welding. The effect of current pulse frequency on weld bead microstructure, tensile strength, and hardness in joining of powder metallurgical steel preform sheets to wrought copper was studied. Considering weld strength as the quality characteristic in the selection of process parameters, the Taguchi method is used to analyse the effect of each process parameter individually and of their interaction on weld strength, and subsequently to determine the process parameters leading to optimum weld strength. The application of pulsed current causes iron dendrites to become more equiaxed and uniformly distributed owing to dendrite fragmentation. Further, there was an optimum frequency range over which the microstructural refinement was maximal. The same optimum frequency range corresponded to maximum tensile strength. Enhanced fluid flow and reduced thermal gradients are thought to be responsible for refining the solidification structure and the resulting stronger welds. 相似文献
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电弧等离子体行为对焊接接头组织结构和性能具有决定性作用,开展气流再压缩等离子弧特性研究对于指导先进材料的气流再压缩等离子弧焊接工艺和提高焊接接头质量具有重要意义. 针对气流再压缩等离子弧焊接新工艺,基于流体动力学和电磁理论,建立气流再压缩等离子弧数值分析模型,采用ANYSYS Fluent软件,通过C语言进行二次开发,定量计算等离子弧温度分布、流场分布、电势分布,分析压缩气对等离子弧温度场、流场、电弧电压的影响规律. 模拟结果表明,压缩气对喷嘴内的等离子弧温度分布基本没有影响,压缩气对喷嘴外的等离子弧具有拘束压缩作用;压缩气对等离子弧流场分布基本没有影响;压缩气能够提高电弧电压. 相同电流条件下,与常规等离子弧焊接相比,气流再压缩等离子弧焊接电弧穿透能力有望提高. 相似文献
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研发了一种单电源双脉冲混合调制VPPA(variable polarity plasma arc,VPPA)焊接系统,在典型VPPA焊接基础上加入高低频调制脉冲,可输出1~5 kHz高频脉冲,1~2 Hz低频脉冲及高低频混合脉冲. 以3003铝合金为试验对象,采用脉冲VPPA焊接方法,对其进行焊接试验,并通过焊接接头拉伸性能测试、显微相组织分析及断口扫描电镜等手段对铝合金的焊接质量和接头性能进行了分析. 结果表明,由于高低频混合脉冲电流的周期性变化,对熔池产生搅拌、冲击作用,从而提高了焊接接头抗拉强度,细化焊缝晶粒组织,断口韧窝趋于均匀且密度增加,提高了铝合金焊缝质量. 相似文献
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提高电弧穿透能力是等离子弧焊接领域的重要课题.自主设计并搭建了金属粉末再压缩等离子弧焊接新工艺试验平台,采集焊接过程电信号、视觉信号、弧光光谱信号等,并从焊缝成形、电弧电压、熔融金属过渡、弧光光谱等方面对金属粉末再压缩等离子弧焊接过程进行了初步的研究.在相同焊接电流195 A条件下,与常规等离子弧焊接工艺相比,金属粉末再压缩等离子弧焊接焊缝熔深增加1.29 mm、熔宽减少1.65 mm、电弧电压升高0.63 V.在波长为230 ~ 270 nm范围内,与常规等离子弧焊接相比,金属粉末再压缩等离子弧焊接中Fe和Cr元素的特征谱线明显增多. 结果表明,在相同电流条件下,与常规等离子弧焊接相比,金属粉末再压缩等离子弧焊接电弧穿透能力增强. 相似文献
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To overcome the shortcomings of conventional plasma arc welding (PAW), the' controlled pulse key-holing' strategy is proposed and the keyhole PAW experiment system is developed. The efflux plasma voltage signal is detected in real-time to characterize the keyhole size and dimension. The welding current waveform for controlled pulse key-holing strategy is implemented, and two slow-decreasing slopes are added at the dropping point from peak current to base current to further reduce both heat input and arc force so that the controllability of keyhole dynamics is improved. Two kinds of PAW tests are conducted, and the different parameters of the controlled pulse current and the relevant efflux plasma voltage are measured in real-time to investigate the effects of welding current waveform parameters on the key-holing condition. 相似文献
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建立了等离子弧焊静止电弧的三维有限元数学模型,考虑等离子气、保护气的作用,利用ANSYS有限元分析软件对电弧的温度场、速度场、压力以及阳极工件表面的电流密度等进行了数值模拟,并与TIG焊进行了比较.结果表明,由于喷嘴的约束作用,等离子弧焊与TIG焊相比,电弧温度显著提高,焊接电流为150 A时电弧最高温度达到30 000 K.等离子弧焊的另一个显著特点是等离子体流速和电弧压力显著增大.通过计算马赫数、有效粘度和动力粘度之比,认为等离子体电弧处于层流不可压缩状态. 相似文献
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研究开发了一种适用于铝合金材料的新型超快速变换复合脉冲方波电流变极性电弧焊接方法,采用变极性TIG平板对接焊接工艺,分别对5A06,2A14和2219三种铝合金材料进行焊接,通过X射线探伤检测、接头拉伸性能测试以及断口扫描电镜等手段对铝合金的焊接质量和接头性能进行测试分析.结果表明,采用过零无死区时间且具有超快速电流上升沿和下降沿变化速率的复合超音频脉冲方波变极性TIG焊接工艺进行铝合金焊接,有利于改善和提高接头性能,获得满意的焊接质量. 相似文献
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Her-Yueh Huang 《Metals and Materials International》2010,16(5):819-825
A systematic study of the effects of activating flux in the weld morphology, arc profile, and angular distortion and microstructure
of two different arc welding processes, namely, Gas Tungsten Arc Welding (GTAW) and Plasma Arc Welding (PAW), was carried
out. The results showed that the activating fluxes affected the penetration capability of arc welding on stainless steel.
An increase in energy density resulting from the arc constriction and anode spot reduction enhanced the penetration capability.
The Depth/Width (D/W) ratio of the weld played a major role in causing angular distortion of the weldment. Also, changes in the cooling rate,
due to different heat source characteristics, influenced the microstructure from the fusion line to the centre of the weld. 相似文献
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《Science & Technology of Welding & Joining》2013,18(4):297-306
AbstractSoft variable polarity plasma arc welding technology has been proposed to solve the problems in horizontal position welding for aluminium alloys. Arc thermal field shape, arc pressure distribution and the characteristic of the weld pool, which are important for keyhole stability, have been changed compared with the ordinary variable polarity plasma arc. Its stability in application can be evaluated by the operational window. The thermal cycle curves, microstructures and microhardness of the horizontal position weld indicate the weld asymmetry. The influence of asymmetry as well as welding defects on tensile strength and fracture behaviour has been studied. The fundamental reason for the asymmetry was considered as the asymmetric fluid flow around the keyhole in the weld pool. 相似文献
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邓厚壁筒形件弧形缩口工艺设计进行讨论,认为采取等体积原则设计变薄引伸弧形模对壁厚进行预成形,完全可以保证最终产品缩口后的尺寸要求,从而取消铰内孔切削加工,该工艺方法在几个产品多年生产实践中应用,取得了较好的经济效益。 相似文献
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Aimed at plasma arc welding, a mathematic model was established according to the theory of magnetic fluid dynamics. The model was numerically analyzed by ANSYS software. The temperature, current density and plasma velocity distributions of normal arc had been simulated and compared with those of double arc. The results show that the appearance of double arc has made the temperature of the nozzle rise up to 5 000 K. The appearance of side arc could make the current density of the main arc decrease, and also make the maximal temperature of the arc reduce. 相似文献