机械制造专业 铝合金电子束焊接工艺分析研究.doc

铝合金电子束焊接工艺分析 摘要 6082-t6 铝合金属于 AI-Mg-Si 热处理强化铝合金。大米由于其重量轻、强度高、挤出成形性好、耐腐蚀性好, 近年来在轨道交通行业, 特别是高速列车车身中得到了广泛的应用。由于铝合金在实际生产中大多用作焊接结构, 传统的焊接方法, 如 TIG 和 MIG, 容易造成焊接结构粗糙、孔隙率高、裂纹大等缺陷, 难以获得高焊接结构。质量焊接接头, 并在一定程度上限制其使用。相比之下, 真空电子束焊接具有能量密度高、热输入小、焊接变形小等特点, 在焊接602-t6 等铝合金方面具有很大的优势。在此基础上, 对厚度分别为8毫米和15毫米的602-t6 铝合金的 EBW 焊接工艺及其接头的微观结构和性能进行了研究。将不同焊接条件下获得的接头的微观结构、机械性能和耐腐蚀性与厚度为8毫米的 MIG 接头进行了比较。细等轴晶粒和枝晶, 具有明显的次生枝晶。晶界和枝晶边界有大量的共晶结构, 分布均匀。圆形扫描方法可以明显细化电子束焊接中的晶粒, 这是由于圆形扫描对熔池金属的强烈搅拌效果, 可以改善熔池金属。介质溶质元素的流动性降低了合金元素的偏析: MIG 焊接接头的焊接结构为粗等轴状和枝晶, 次生枝晶不明显。XRD 相分析表明, 焊缝金属主要为铝基体相, 含有少量的贝塔 (Mg2Si 强化相和元素硅)。EBW 关节和 MIG 关节的相组成基本相同。透射电镜观察和分析进一步证实, 焊缝中的强化阶段主要是贝塔 (MgzSi) 阶段。 显微硬度分布试验表明, EBW 接头焊缝的硬度低于 HAZ 和基体金属本身, haz 宽度较窄, 软化程度较轻。圆扫描法获得的 EBW 接头焊缝硬度最高, 其次是线性扫描, 无扫描法获得的接头焊缝硬度最低。MIG 焊接接头热影响区 (HAZ) 宽度较大, 软化区明显, 是焊接接头最弱的区域。 节点拉伸性能试验表明, 几个接头的焊接质量良好, 能满足实际工程结构的强度要求。EBW 接头的最高抗拉强度为贱金属强度的 84.1%, 而 MIG 接头的抗拉强度相对较低, EBW 接头的抗拉强度仅为贱金属强度的686%。拉伸断裂扫描表明, 接头的拉伸断裂表现出明显的韧性断裂特征。关节表面有大量的酒窝。酒窝的大小和深度各不相同, 在酒窝底部可以清楚地观察到第二相粒子。进一步的 EDS 分析表明, 这些二相粒子主要是 (Mg2Si) 相。 采用静态失重法和电化学试验法评价焊接接头的耐腐蚀性。结果表明, 对于8mm 厚602-T6 铝合金的焊接接头, 圆形扫描方法是获得接头 A5 耐腐蚀性的最佳途径。相比之下, MIG 焊接接头的耐腐蚀性较差。 总之, 在实验条件下, 8mm 厚6082-T6 铝合金 EBW 接头的整体性能高于 MIG 焊接接头, 最佳工艺参数为: 电子束 I = 105 mA, 焊接电压 U = 50Kv, 焊接速度 v = 1500 毫米: 最小, 圆形扫描;15mm 厚602-T6 铝合金的最佳 I 工艺参数为: 电子东流 I = 205mA, 焊接电压 U = 50kv, 焊接速度 v = 1500 mmmin ', 以及圆形扫描。形状扫描模式。 关键词: 6082-T6 铝合金，电子束焊，MIG焊，显微组织，力学性能，耐腐蚀性 Abstract The 6082-t6 aluminum alloy belongs to ai-mg-si heat-treatable aluminum alloy. Due to its light weight, high strength, good extrusion molding and corrosion resistance, it has been widely used in the rail transit industry in recent years, especially in the body of high-speed trains. As this aluminum alloy is mostly used as a welding structure in practical production, the use of traditional welding methods such as TIG and MIG will easily lead to defects such as thick weld structure, high porosity of weld seam and thermal crack, which makes it difficult to obtain high-quality welded joints and limits its use to a certain extent. In comparison, vacuum electron beam welding (EBW) has the characteristics of high energy density, small heat input, small welding deformation, etc., and has great advantages for welding of 6082-t6 aluminum alloys. Based on this, in this paper, the thickness of 8 mm and 15 mm respectively 6082 - T6 aluminum alloy EBW welding process and the joint microstructure and properties was studied, and the thickness of 8 mm, comparing the microstructure and properties of MIG welding head analysis under the condition of different welding technology for joint microstructure, mechanical properties and corrosion resistant properties of difference and its reason. Weld joint microstructure observation showed that the EBW joint organization for small isometric and dendrites, has obvious secondary branch, with a large number of grain boundary distribution in grain boundary and branches eutectic organization, and evenly distributed: using circular scanning of electron beam welding way can significantly refine the grain size, this is due to the circular scanning has strong stirring effect of molten pool of metal, and can improve the mobility of solute elements in molten pool of metal, reduce the segregation of alloying elements: the weld microstructure of MIG welding head for a bulky isometric and dendrites, secondary dendrite is not obvious. XRD phase analysis of the joint weld shows that the metal of the joint weld is mainly a-al matrix phase, and contains a small amount of (Mg2Si strengthening phase and elemental Si. In terms of phase structure, EBW joint and MIG welding joint are basically the same. By TEM observation and analysis, it is confirmed that the strengthening phase is mainly (MgzSi) phase. Joint distribution of microhardness tests show that the EBW joint weld hardness value is lower than the heat affected zone and base itself, heat affected zone width is narrower, the softening to a lesser degree, and adopts circular scanning method to obtain the highest hardness value of joint weld area, line scan times, did not add to scan for joint weld hardness value is the lowest. However, the width of heat affected zone of MIG welding joint is relatively large, and there is an obvious softening zone, which is the weakest area of welding joint. The test results show that the welding quality of several joints is good, which can meet the strength requirement of practical engineering structure. Among them, the tensile strength of EBW joint is up to 84.1% of the strength of the base metal itself, while the strength of MIG welding joint is relatively low, and its tensile strength is only 68.6% of the strength of the base metal itself. The scanning observation of the tensile fracture showed that the tensile fracture of the joint presented obvious ductile fracture characteristics, and there were a large number of dimples on the surface of the fracture, with different sizes and depths. Moreover, the