【作者】 李金宝；

【导师】 孙大千；

【作者基本信息】 吉林大学 ， 材料加工工程， 2006， 硕士

【摘要】 本文采用钨极氩弧焊(TIG)对AZ91D镁合金进行了焊补试验和熔化极氩弧焊(MIG)对AZ31B镁合金进行了对接试验,研究了镁合金焊接接头的组织及力学性能,探讨了焊接工艺参数和焊丝成分对焊接接头组织和力学性能的影响规律及镁合金焊接裂纹特点。研究表明,镁合金的焊接接头包括焊缝区、热影响区和母材区,焊缝区的晶粒细小,而热影响区的晶粒较为粗大。AZ91D、AZ31B镁合金母材和焊缝的相结构均为镁固溶体(α-Mg)和金属间化合物(β-Al12Mg17)。焊丝成分和工艺参数对镁合金焊接接头组织和力学性能影响较大。在镁合金焊接过程中,最常见的是弧坑裂纹,有时也看到沿焊缝中心的纵向裂纹,镁合金焊接裂纹主要为结晶裂纹。控制焊缝中低熔点共晶体的含量,降低接头拉伸应力可能是改善镁合金焊缝结晶裂纹敏感性的有效措施。更多还原

【Abstract】 It has become a higher request for weight saving and recycle of materials to reduce the energy consumption and pollution with the rapid development of aerospace, automobile and electron industries. Magnesium alloys, the lightest structural material, have many advantages such as high strength ratio, good castability, high damping capacity and recycleable characteristic, which are praised as the most potential materials to achieve weight saving and recycle. They have been attracting increasing interest. Society’s demands promote basic theory research and production technical level of magnesium alloys, then promote the applications of magnesium alloys in industry fields. The application of any advanced material not only depends on its own properties, but also relies on the technologies of material manufacturing. Besides, manufacturing techniques such as welding and joining play an important role in exploiting the new fields of applications. It is difficult to bond magnesium parts, because magnesium alloys are extremely easy to form the oxide film. Furthermore, during welding there are also pore and crack, which reduce the mechanical properties of welded joints. However, up to now, the information on welding metallurgy, weldability and welding process of magnesium alloys is still limited, and many welding theoretics and technologies of magnesium alloys have not been solved. It has become one of main problems for welding of magnesium alloys.Effects of weld composition and welding parameters on microstructures and mechanical properties of tungsten inert gas (TIG) and metel inert gas (MIG) welded magnesium alloy joints have been investigated. Microstructures and compositions of the joints were investigated by optical and scanning electron microscopy (SEM) equipped with energy-dispersive spectrometer (EDS), X-ray diffraction (XRD) and an image analysis system. Besides, the characteristics of weld crack have been investigated. By analyzing the experimental data, some conclusions have been drawn as follows:更多还原