铝合金多层结构整体连接工艺研究

发布时间：2018-03-30 10:25

  本文选题：铝合金多层结构　切入点：钎焊　出处：《南京理工大学》2017年硕士论文

【摘要】：目前,国内外雷达天线和散热器广泛采用铝合金薄壁复杂多层结构。铝合金多层结构具有形状复杂、通道壁薄、焊接面狭窄、尺寸形位精度要求高及制造难度大的特点,所以铝合金多层结构普遍存在焊接质量不稳定、成品率不高的问题。本文本文采用了钎焊、钎接-扩散复合焊接和扩散焊方法连接铝合金多层结构,通过研究焊接接头的界面组织结构,分析了不同工艺参数对接头界面、力学性能及变形量的影响,并通过ANSYS有限元分析软件,从而有效地指导了控制零件焊接变形的试验,最终获得了比较理想的焊接接头。采用Al-Si-Mg钎料对3A21铝合金多层结构进行了钎焊试验,在钎焊温度610℃,保温时间10min条件下获得最佳接头,强度可达72 MPa。采用Al-Si-Mg钎料对3A21铝合金多层结构进行了钎接-扩散复合焊接试验,在钎焊温度610℃,保温时间10 min,扩散焊温度560℃,压力0.5 MPa,扩散时间60 min下,获得理想接头,强度达到81 MPa。由于钎焊后的扩散焊使得钎焊中容易出现的未焊合和空洞等缺陷得以消除,元素扩散更充分,因此钎接-扩散复合焊接所得接头质量明显好于钎焊接头。对3A21铝合金多层复杂结构焊接接头焊缝进行了EDS分析,两种方法的钎料与母材的元素均均匀扩散,且钎接-扩散复合焊接元素扩散更均匀。焊缝都主要包括蜂窝状的Al基体、块状富Si相和初晶Si等。另外还出现Mg和Si形成Mg2Si强化相,提高了接头性能。采用直接扩散焊焊接了 6061铝合金多层结构,在焊接温度560℃,焊接压力为4 MPa,保温时间为60 min下所得的最佳接头强度达到140 MPa;加Al-Si中间层扩散焊,在焊接温度为580℃,焊接时间为30min,焊接压力2MPa,焊接温度为520℃,焊接时间为60min,焊接压力为1MPa下所得接头具有更好的接头质量和更高的接头强度,强度达到150 MPa。对6061铝合金多层复杂结构扩散连接接头焊缝进行了元素与组织分析,焊缝都主要包括α-Al基体相、Al4Si相、单质Si相和Mg2Si强化相等。采用分段加压的方法显著减小了变形量,变形率比只采用恒定压力的变形率减小了 0.3%。在有限元模拟结果的指导下,有针对性的设计和优化了焊接方法及工艺参数,从而有效地控制了零件的焊接变形。
[Abstract]:At present, aluminum alloy thin wall complex multilayer structure is widely used in radar antenna and radiator at home and abroad. Aluminum alloy multilayer structure has the characteristics of complex shape, thin channel wall, narrow welding joint, high precision of dimension and position and high difficulty in manufacturing. Therefore, the welding quality is unstable and the product rate is not high in the multilayer structure of aluminum alloy. In this paper, brazing, brazing and diffusion welding are used to connect the multilayer structure of aluminum alloy. The influence of different process parameters on the interface, mechanical properties and deformation of welded joints is analyzed by studying the interface structure of welded joints, and the ANSYS finite element analysis software is used to guide the experiment of controlling welding deformation effectively. Finally, an ideal welding joint was obtained. The multilayer structure of 3A21 aluminum alloy was brazed with Al-Si-Mg filler metal. The best joint was obtained under the condition of brazing temperature 610 鈩，

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