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采用镶嵌异种材料作为标识材料的方法,用不同搅拌针形状的搅拌头,进行了搅拌摩擦焊试验.结果表明,搅拌针形状影响焊缝塑化金属流动的行为,导致焊缝截面形貌发生变化.搅拌针表面的反螺纹使搅拌针周围塑化金属向下流动,迫使搅拌针端部周边金属向上运动,焊核中心处于焊缝横截面下部;正螺纹使搅拌针周围塑化金属向上流动,迫使轴肩下方及周边金属向下运动,焊核中心处于焊缝横截面上部.改变搅拌针形状及长度,可以改变搅拌针下方及附近区域塑化金属的流动形态,从而改变焊缝底部的成形及包铝层进入焊缝的深度. 相似文献
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采用铝箔作为标示材料,用不同旋向、不同螺距的搅拌针进行了搅拌摩擦焊试验.结果表明,搅拌针的旋向决定塑性金属在厚度方向上的迁移方向,带左旋螺纹的搅拌针驱使搅拌针附近的塑化金属向下迁移,向下迁移的金属不断向焊缝底部积累并受到垫板的阻碍作用,迫使塑性金属挤压外围的材料向上迁移,右旋螺纹的搅拌针作用方式则相反;建立的"抽吸-挤压"模型能很好的解释塑性金属在焊缝厚度方向上的迁移方式;螺距较大的搅拌针有利于塑性金属在焊缝厚度方向上的迁移,但也容易使焊缝底部的包铝层卷入焊缝中. 相似文献
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研究了在铝合金薄板与铜箔交替叠加的多层板搅拌摩擦焊过程中焊缝金属的塑性流动行为.结果表明,用带螺纹的搅拌针焊接时,搅拌针周围金属沿螺纹在焊缝厚度方向产生剧烈的流动,在螺纹端部脱离搅拌针并向周围挤压母材,形成实心环形挤压区,与周围母材有明显的界面.洋葱瓣花纹是实心环形挤压区在焊缝横截面上的表现形式.搅拌针表面的螺纹提供金属在焊缝厚度方向流动的驱动力.搅拌头顺时针旋转时,用左螺纹搅拌针焊接的焊缝横截面上,洋葱瓣花纹的中心偏向焊缝底部;用右螺纹搅拌针焊接的横截面上,花纹的中心偏向焊缝表面. 相似文献
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利用超声波对金属塑性成形作用对LF21铝合金进行了超声搅拌摩擦焊接试验,并对常规搅拌摩擦焊与超声搅拌摩擦焊接头的微观组织、断口形貌进行了对比分析.结果表明,超声能量通过搅拌头有效地导入焊缝底部,在增加焊缝底部搅拌强度的同时,提高了搅拌针周围金属原子的运动和扩散能力,焊核区的金属组织有明显的晶粒细化和组织均匀化.超声搅拌摩擦焊断口韧窝数量与深度均不及常规搅拌摩擦焊,撕裂棱不明显;超声搅拌摩擦焊可以提高接头力学性能,但平均断后伸长率相比常规搅拌摩擦焊有所下降. 相似文献
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研究了20 mm厚2024-T4铝合金板材在搅拌摩擦焊过程中,搅拌针锥度与搅拌针表面螺纹头数对焊缝塑性金属在搅拌针周围迁移程度的影响.结果表明,随搅拌针螺纹头数增加,搅拌头旋转1圈时搅拌针螺纹所转移的高温金属量增加,焊核中塑性金属在前进边和返回边的轴向上迁移程度增加,宏观表现为焊核高度、宽度和面积增大;搅拌针锥度由25°减少至15°时,焊缝塑化金属量增加,焊核塑性金属在焊缝横截面上横向和轴向的迁移程度都增大,焊核面积增大.采用多头螺纹和较小锥度的搅拌针,可以改善厚板焊接时温度梯度大、焊缝金属流动不充分的问题,保证焊缝冶金质量. 相似文献
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The double-side image sensing of the keyhole puddle in the variable polarity plasma arc welding of aluminum alloys has been investigated in this paper, to extract the characteristically geometrical size of the keyhole and to realize the feedback controlling for weld formation in the welding process. Some geometrical sizes of the visible keyhole in the front and back images such as the width, height, area, etc. can be used to monitor both the keyhole puddle and the weld formation in the welding process. Under the condition of the varied heat sink, varied gap and misalignment, the trend from normal welding to cutting can be reflected from the variations of geometrical sizes of the keyhole puddle respectively. The keyhole area, the keyhole height and the shape parameters of the keyhole puddle are the key parameters which reflect the trend from normal welding to cutting when meeting the condition of the varied heat sink, varied gap and misalignment respectively. The algorithm for the image processing of the keyhole puddle and the periphery extracting of the visible keyhole developed in the paper can be used to determine real-timely the geometrical sizes of the visible keyhole. Artificial neural network is applied to establish the model for predicting the geometrical sizes of the back keyhole puddle. The inputs of the model are the geometrical sizes of the front keyhole puddle and the weld parameters, the outputs of the model are the geometrical sizes of the back keyhole puddle. The model can be used to control the stability of keyhole and the weld formation. 相似文献
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Plasma arc welding was used to join SiCp/ml composite with titanium as alloying filler material. Microstructure of the weld was characterized by an optical microscope. The results show that the harmful needle-like phase Al4C3 is completely eliminated in the weld of SiCp/Al metal matrix composite(MMC) by in-situ weld-alloying/plasma arc welding with titanium as the alloying element. The wetting property between reinforced phase and Al matrix is improved, a stable weld puddle is gotten and a novel composite-material welded joint reinforced by TiN, AlN and TiC is produced. And the tensile-strength and malleability of the welded joints are improved effectively because of the use of titanium. 相似文献
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本文对脉冲等离子焊接锅炉管系的研究工作中一些主要结果进行了论述,如焊接参数对焊接熔池控制的影响,主要焊接参数的匹配及主控参数的选定,焊接缺陷与消除方法及其在生产使用中的情况。还讨论了取等离子弧穿透时产生的音响讯号作为工艺适应控制讯号的问题。 相似文献
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利用福禄克RAYPi20HTRC红外热像仪,获取焊接熔池的红外热成像图像,通过软件对焊接熔池热成像图像进行处理,依据焊接熔池温度梯度分布对当前时刻焊接成型和焊接质量进行判断,识别和判断焊接缺陷,利用算法和程序对焊接质量进行评估,并记录当前的焊接时间和焊接点位,生成焊接记录。系统经过油气管道激光/电弧复合焊接应用试验具有运行稳定、质量评价与缺陷判定准确的特点,可以为现场焊接质量监测和后续焊接质量检测提供重要参考,具有重要工程应用意义。 相似文献
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文中针对常规水下湿法焊接过程中焊缝力学性能低的问题,设计了超声振动辅助水下湿法焊接的方法. 通过超声辐射端将超声振动能量施加在电弧前方的待焊区域,进而通过工件将超声能量传递到熔池中,对比研究了超声振动对焊缝成形、微观组织及力学性能的影响. 结果表明,超声振动能够减小焊缝截面不对称,增加焊缝深宽比,使熔池发生强烈的搅拌作用,具有细化晶粒的作用,并降低熔合区处柱状结晶的倾向. 与常规水下湿法焊接相比,超声振动辅助水下湿法焊接抗拉强度明显提高,达到母材的92.4%;焊缝区显微硬度升高,热影响区硬度值变化较小. 相似文献
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R. Cao S.S. Zhu W. FengY. Peng F. JiangW.S. DU Z.L. TianJ.H. Chen 《Journal of Materials Processing Technology》2011,211(4):759-772
This work investigated the variations of Charpy V toughness which was measured in various parts of welding joints of a 980 MPa steel. The welding joints were composed of multi-pass weld metal, heat affected zones (HAZs) and base metal. Two types of weld metals, one with inferior toughness and the other with comparable toughness to the base metal, were used to reveal the effects of weld metal property and fraction on the toughness of the welding joint as a whole. The notches of Charpy V specimens were located at various sections of the welding joints where the ligaments comprised various fractions of weld metal. The results revealed that the weld metal with inferior toughness, even in a fraction as low as 20%, caused remarkable deterioration on the impact toughness of the welding joint. The weld metal with comparable toughness had little effect on the properties of the welding joint. The microstructures and fracture surfaces were observed to analyze the mechanism of the inferior toughness in a MAG weld metal. 相似文献
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本文研究了焊前清理和处理对气孔形成的影响,进行了改变焊接速度和氩弧点焊试验以观察熔池存在时间对气孔形成的影响。用扫描电镜对带气孔焊缝断面和气孔内表面进行观察,发现多数气孔内表面上有直径约1μ的微气泡和个别固体质点。分析了气孔的形成过程,根据前人的工作和我们的工作发展了气孔形成的“气孔核”观点,认为上述微气泡和固体质点起到“气孔核”作用,其中以微气泡的怍用为主。把气孔分为熔合线气孔和焊缝中部气孔,讨论了两类气孔形成过程的差别。焊前清理和热处理减少气孔是由于减少了“气孔核”的结果。上述观点完满地解释了前人难以解释的现象。 相似文献
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采用Nd:YAG激光对强度为800MPa,厚度为1.2mm的TRIP钢板进行焊接.研究焊接速度对焊缝外观和截面成形的影响及接头的组织特点、硬度、强度和成形能力.激光功率相同,焊接速度较低时焊缝易产生气孔,速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝组织主要由马氏体构成,从焊缝、热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝中出现马氏体,接头的塑性和韧性降低,板材的冲压成形能力下降. 相似文献