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    摘  要 钢/铌复合焊接结构可以提高航空发动机工作温度、减轻其重量，使航空发动机具有更高的推重比，在航空航天领域具有广阔的应用与发展前景，是当今学术界研究的热点。本文采用激光焊对钢/铌进行连接，利用光学显微镜、EDS、XRD 及能谱仪观察并分析焊接接头的组织和成分。 研究结果表明，在一定的工艺参数下，激光焊可以实现钢和铌的连接。铌和 304不锈钢直接焊接后，在焊缝中会产生金属间化合物层。由于金属间化合物层的存在，会加大焊接接头的开裂倾向，使焊缝强度降低，甚至导致断裂。正因为直接焊的接头容易产生金属间化合物，本文研究在焊缝中加入过渡层。在焊缝中添加Ag-V过渡层可以实现铌和304 不锈钢的连接。研究表明，加入过渡层后，焊缝中存在的金属间化合物很少。通过在焊缝中添加了过渡层，减少了焊缝中的金属间化合物，减小了焊接接头的开裂倾向，实现了连接。其中，Ag-V 过渡层的接头的强度比 Ag-Mo、Cu-V、Cu-Mo 过渡层得到的接头的强度高。58970   
    毕业论文关键词：钢/铌；激光焊接；金属间化合物；Ag-V过渡层     Abstract Steel/niobium compound welding structure can improve operating temperature of the aircraft engine,reduce its weight and make the aircraft engine with higher thrust to weight ratio.Steel/niobium compound welding structure  has broad application and development prospects  in the aerospace field.It  is the hot spot of academic research. In this paper,the laser welding is used to connect the steel and niobium.The microstructure and composition of the welded joint were observed and  analyzed  by optical microscope,EDS,XRD and energy spectrometer.  Research results show that  laser welding can realize the connection of steel and niobium under certain technological parameters. Intermetallic compound layer will be produced in the weld metal  after the direct welding of niobium and 304 stainless steel.  Because of the existence of the intermetallic compound layer, the cracking tendency of the welded joint can be increased  and  the strength of the weld is reduced.The intermetallic compound layer  can  even lead to fracture.Because of the direct welding joint is easy to produce intermetallic compounds,this paper studies adding the filling layer in the weld.The connection of niobium and 304 stainless steel can be realized by adding Ag-V filling layer in the weld.The research shows that there are few metal compounds in the weld after adding the filler layer.Because the filling layer is added in the weld,the metal compound in the weld is reduced.The cracking tendency of the welding joint is reduced and  the connection is realized.The strength of joints of Ag-V filled layer is higher than that of Ag-Mo,Cu-V,and Cu-Mo filling layer.   
    Key words: steel /niobium; laser welding; intermetallic compound; Ag-V filling layer

    目录

    第一章绪论.....1

    1.1课题的背景和意义.....1

    1.2不锈钢与铌的焊接性...2

    1.2.1根据物理性能分析不锈钢与铌的焊接性.....2

    1.2.2根据冶金学分析不锈钢与铌的焊接性.3

    1.3不锈钢与铌的焊接研究现状...5

    1.3.1熔化焊...5

    1.3.2钎焊.....6

    1.3.3熔钎焊...7

    1.3.4爆炸焊...8

    1.4金属间化合物....9

    1.5课题主要研究内容.....10

    第二章实验材料、设备和方法.....11

    2.1实验材料11

    2.2激光焊接设备...12

    2.3激光焊接实验..13

    2.3.1焊前准备13

    2.3.2施焊....13

    2.4分析测试方法..14

    2.4.1焊接接头拉伸试验....14

    2.4.2微观组织分析..14

    2.4.3断口形貌分析..15

    2.4.4相组成分析....15

  1. 上一篇：搅拌摩擦焊接过程振动与受力特征分析
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