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综述了焊缝金属强度匹配与扩散氢的关系。结果表明,常用焊接方法焊缝中氢的来源主要是焊接材料中的水分、坡口杂质及电弧周围的水气等。在焊缝中氢的影响因素中,GMAW方法扩散氢最低,电弧中除氢冶金反应取决于焊接方法,辅助除氢工艺作用不可小觑。高强钢采用低强匹配焊缝时,HAZ形成富氢带,是接头的薄弱环节;采用高强匹配焊缝时,HAZ富氢带不显著,而焊缝中的氢含量高,成为接头的薄弱环节。三种焊缝强度匹配与扩散氢关系的工程应用均获得了满意的工程质量;在马氏体耐热钢及其异种钢焊接中,高强匹配焊缝阻止HAZ形成富氢带的创新理论,尚需深入研究。 相似文献
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以TIG焊接电弧为对象,依据磁流体动力学理论构建电弧的数学模型,运用ANSYS有限元分析软件对二维稳态下轴对称的、氩氮混合气体保护的TIG焊接电弧进行了数值分析,得到了50%N2 Ar混合气体保护下焊接电弧的温度场、速度场的形态分布特征.并通过与纯氩气保护的TIG焊接电弧温度、压力以及等离子体速度等分布的比较,得出了加入氮气作为保护气体时,TIG焊接电弧能量及形态的分布变化.对比结果表明,加入氮气作为保护气体提高了TIG焊接电弧的电弧温度、等离子体速度和电弧压力,能得到更高能量密度的焊接电弧. 相似文献
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测定电弧温度对于深入理解焊接电弧在不同环境下的物理特性,从而寻求改善焊接质量的新途径有重要意义.笔者介绍了电弧等离子体光谱理论及光谱诊断方法,对TIG焊电弧光谱进行了采样分析.通过对光谱数据的分析指出钨元素谱线具有较好的利用价值.利用等离子体光谱诊断法对不同电流和不同弧长的电弧光谱和电弧温度进行了对比分析,并时其变化规律做出了解释.本研究工作对于输油管TIG焊接电弧物理的研究具有参考价值. 相似文献
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针对活性剂等离子弧焊焊接过程,对焊接电弧外形的变化,焊接电弧电压与活性剂之间的关系进行了研究,采用红外热像伪着色法测定了活性剂等离子弧焊焊接电弧温度场,并建立了活性剂等离子弧焊焊接电弧热流密度径向分布模型.研究结果表明,活性剂等离子弧焊焊接电弧收缩,弧尾翼消失,尾焰加大,电弧穿透力增强,电弧电压升高;活性剂等离子弧焊焊接电弧的温度分布比较紧凑,温度场外形窄,温度分布范围较集中,电弧径向温度梯度较大;电弧径向温度分布呈现正态Gauss分布模式;使用活性剂后的焊接接头性能与未使用活性剂焊接接头相当. 相似文献
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Abstract On the basis of plasma physics and optical spectroscopy theories, a new method named ‘Multilineal spectroscopy analytic solution’ for measuring welding arc plasmas is proposed. Using this method and the relevant measurement system, the radial distribution of hydrogen concentration is measured, together with the corresponding temperature and pressure in a TIG welding arc. The principles of the method and the relevant measuring system are described. Verification of the measured results is also given in this paper. The method is characterised by real time, quantitative and simultaneous measurement of multi-parameter space distributions. It can be applied to the measurement of various elements in a welding arc in principle, and may be considered as an effective way to solve many practical and theoretical problems in welding engineering. 相似文献
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本文介绍了一种新的焊接方法——真空磁压缩等离子弧焊接。真空磁压缩等离子弧是将低真空中的自由电弧用与电极同轴向的磁场压缩后获得的。实验表明,随着气压的降低,自由电弧会越来越扩展,弧根区的电流密度越来越低,直至产生“旁弧”,不能稳定燃烧而熄灭。而且这种低真空自由电弧难以用和普通等离子弧相似的机械方法压缩。采用轴向磁场可以有效地压缩真空电弧。磁压缩的效果随气压的降低趋于明显,气压低于1.33×10~2Pa 时,几十分之一特斯拉(T)的磁场就可获得略粗于电极、上下直径近似相等的弧柱,我们称之为真空磁压缩等离子弧。使用真空磁压缩等离子弧作为热源,可以焊接一般金属和活泼金属,其熔透工件的能力可超过大气氩弧,并可用调节磁场强度的方法,调节电弧的能量分布。与常规氩弧焊、等离子孤焊、电子束焊相比,真空磁压缩等离子弧焊接有其独到的优点,可望在不久的将来获得广泛的应用。 相似文献
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Xiao Xiao Xueming Hua Fang Li Yixiong Wu 《Journal of Materials Processing Technology》2014,214(11):2770-2776
The monochromatic images of 794.8 nm Ar I and 487.98 nm Ar II spectrums are obtained by high speed camera, and these images are normalized with respect to their relative maximum emission coefficient in a pure argon (single element) arc. The relative maximum emission coefficient of 487.98 nm Ar II is calculated based on Olsen-Richter diagram. Unlike other spectroscopic methods, the presented method does not require spectra scan or the maximum emission coefficient of non-argon elements. This technique is applied to the measurement of radial profile of temperature and gas composition of argon–helium arc plasma in gas tungsten arc welding (GTAW), significant demixing occurs in the argon–helium arc plasma. Helium concentration in arc plasma is higher than that in original gas mixture, and it decreases as the point moves away from the axis along radial direction and increases as the point gets closer to the cathode. The calculated arc temperature and gas composition are compared with the data obtained using conventional method where a spectrometer is used for spectral line intensity measurement and two-line relative intensity method for calculation. Very good agreements have been observed. That means, the developed technique measures arc temperature and gas composition as accurate as the conventional spectroscopic methods. With the usage of a high speed camera, the developed technique enables measurement of arc temperature and gas composition distribution in a dynamic arc such as arc ignition, pulsing arc. 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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《Science & Technology of Welding & Joining》2013,18(1):80-86
AbstractThis work presents a new method for through the arc estimation of welding parameters in gas metal arc welding based on signature images. The method is generally applicable and makes use of a novel data fitting procedure. The work covers unassisted through the arc estimation, without auxiliary techniques such as welding head oscillation. The technique is demonstrated for both pulse and short circuiting welding, with estimation of position relative to an overlap joint and a narrow gap weld, and estimation of the width of a 'V' groove. The accuracy of the technique is affected by how closely the welding signatures match the fitting data and the signature image quality match provides a valuable check which shows when through the arc estimates cannot be relied on. Overall, the results demonstrate that through the arc measurements can have application in specialised situations, although accuracy is ultimately limited by phenomena that affect the arc and are not correlated with the measurement. 相似文献
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SONG Yonglun 《中国焊接》1997,(2)
0IntroductionRadiationisanimportantphenomenonofarcweldingprocess.Essentially,itreflectsthephysicalprocessesoccUrringinthearcregion.Ithasbeennotedthattheinformationconcerningthearcprocess,suchastemperature.componentsandtheirdistributions.canberealizedthroughtheobservationofradiationbyarcself-emissionl'.ZI.Therefore,moreknowledgeaboutthefeatUresoftheradiationisneededtoenhancetheunderstandingofti)eldingarc.Inthisarticle.somephenomenaofweldingarcradiation,suchaspossiblewavelengthrangeoftheradiat… 相似文献
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等离子弧焊接SiCp/Al基复合材料焊缝“原位”合金化分析 总被引:11,自引:2,他引:11
采用等离子弧焊焊接SiCp/Al基复合材料,以Ar+N2为离子气,并以Ti作为合金化填充材料,研究了焊缝“原位”合金化元素Ti对焊缝显微组织的影响。结果表明,采用焊缝原位合金化方法焊接SiC颗粒增强铝基复合材料(sicp/A1MMCs),可以有效抑制焊缝中针状脆性相Al4C3的形成,并且由于耶的加入,改善了增强相和Al基体之间的润湿性,形成了稳定的熔池,得到以均匀分布的TiN、AlN等为增强相的新型铝基复合材料焊缝,焊接性能得到有效提高。同时还研究了Ti的添加量对焊缝显微组织的影响,结果发现,随着耶含量的增加,焊缝中还生成如Ti5Si3等新的增强相。焊缝“原位”合金化等离子弧焊接是焊接SiCp/Al基复合材料的一种新方法。 相似文献