A5083铝合金焊缝缺陷涡流检测及缺陷评级

发布时间：2019-04-18 23:06

【摘要】：A5083铝合金及其焊接接头在工业中有着重要应用。目前常采用多道MIG焊进行焊接,焊接过程中不可避免产生各种缺陷。利用多频涡流检测技术可对这些缺陷信号规律进行研究。同时利用BS7910-2005标准对缺陷进行评定,判定焊接接头的质量等级,为含缺陷焊接接头结构设计提供基础数据。本论文首先采用多频涡流技术对不同接头型式(对接、搭接、角接)及不同表面状态(打磨、未打磨)焊缝中不同方向、不同深度缺陷进行检测,对缺陷信号的形态特征,信号幅值的变化规律进行了详细研究。同时,采用合理的方法,成功制造出含裂纹、含气孔的焊接接头,对接头质量进行检测判定。对于不同接头型式或不同表面状态的试样,表面缺陷基本呈现“叶轮”特征,近表面缺陷信号的“叶轮”形特征不明显,信号的不规则性更大,这是由于埋藏缺陷的加工精度影响所致。搭接、角接试件焊缝表面缺陷局部信号有明显缠结,而对接焊缝不存在上述情况。除表面打磨型材对接接头,其余不同型式,不同表面状态的接头纵向缺陷信号幅值变化更加集中,而横向缺陷幅值差异相对较大。槽深增加,缺陷信号幅值增大;横向埋藏缺陷信号幅值小于横向表面缺陷信号幅值。不同接头型式,除横向埋藏缺陷,对接焊缝的缺陷信号幅值最大,与搭接焊缝和角接焊缝缺陷信号幅值差异明显;不同表面状态试件的横向缺陷,焊缝打磨状态的信号幅值高于未打磨状态,而纵向缺陷信号呈现相反的规律。对标准试件、含裂纹试件、含气孔试件焊缝质量等级进行评定,结果分别为Q2, Q2, Q3。
[Abstract]:A5083 aluminum alloy and its welded joints have important applications in industry. At present, multi-pass MIG welding is often used, which inevitably leads to various defects in the welding process. The multi-frequency eddy current testing technique can be used to study the signal regularity of these defects. At the same time, the BS7910-2005 standard is used to evaluate the defects and determine the quality grade of welded joints, which provides the basic data for the structural design of welded joints with defects. Firstly, the multi-frequency eddy current technique is used to detect the defects in different weld joints (butt, lap, corner) and different surface states (grinding, unpolished) in different directions and depths, and the morphological characteristics of the defect signals are analyzed. The variation rule of signal amplitude is studied in detail. At the same time, the welding joint with cracks and pores was successfully manufactured by reasonable method, and the quality of the joint was tested and judged. For the samples with different joint types or different surface states, the surface defects are basically "impeller" characteristics, and the "impeller" shape characteristics of the near surface defect signals are not obvious, and the signal irregularity is greater. This is due to the influence of machining accuracy of buried defects. There is obvious entanglement in the local signal of weld surface defects in corner joints, but not in butt welds. In addition to the butt joint of surface grinding profile, the amplitude of longitudinal defect signal of joints with different surface states is more concentrated, while the amplitude difference of transverse defect is relatively large in different types of joints. With the increase of groove depth, the amplitude of defect signal increases, and the amplitude of transverse buried defect signal is smaller than that of transverse surface defect signal. In different joint types, except for transverse buried defects, the defect signal amplitude of butt weld is the largest, which is obviously different from that of lap weld and fillet weld. For transverse defects of specimens with different surface states, the signal amplitude of weld grinding state is higher than that of non-grinding state, while the longitudinal defect signal shows opposite rule. The quality grade of weld seam of standard specimen, crack specimen and gas hole specimen is evaluated. The results are Q2, Q2 and Q3.The results are as follows: Q2, Q3.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG115.28

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