镁合金焊接接头的毕业设计论文.docVIP

摘 要 我国镁资源极为丰富，镁的储量、产量以及出口量均居世界第一。镁合金由于具有质轻、耐用、减震、可回收性强等众多优点，被公认为最有前途的轻量化材料及二十一世纪的绿色金属材料，将成为继铝合金后又一具有巨大市场的轻金属材料产业，在资源、环保成为经济发展瓶颈的今天，其应用前景十分广阔。特别是Mg-Al系列合金在汽车上有广阔的应用前景，是汽车上最具有减重潜力的部件。但是现有对镁合金材料性能的研究，几乎都是针对镁合金的准静态载荷，缺少高速冲击载荷下的镁合金动态性能数据，这无疑使得将镁合金作为防弹及汽车结构材料的设计缺少了依据。因此，研究镁合金在高速冲击载荷下的力学性能、断裂规律及失效形式可以为提高镁合金安全性设计方面提供理论依据。 本文综合应用了金相分析、断口形貌分析等手段研究了高应变速率下镁合金焊接接头的力学行为及微观组织演变。探索高速压缩载荷作用下的镁合金焊接接头变形与失效机制，以便最终提高材料的性能。 实验结果表明：在不同应变速率下变形时，两种焊接方法下（TIG焊和摩擦搅拌焊），AZ31 镁合金板材的焊接接头的应力—应变曲线几乎重合，说明AZ31 镁合金板材的焊接接头的应力对应变速率不敏感。动态压缩断裂方式均为准解理断裂.冲击试样横截面金相组织均有孪晶，镁合金打击后晶粒大小不均匀。 关键词：镁合金焊接接头；动态力学性能；摩擦搅拌焊；微观组织 Abstract Magnesium resources is very rich in China . Magnesium reserves, production and export volume ranked first in the world. Magnesium alloys have been recognized as the most promising lightweight materials and green metallic materials in the twenty-first century because of its light weight, durability, shock absorption, recyclable, and many other advantages. It will has a huge market after Aluminum Alloy. And its application has a bright future, in the present when resources, environmental protection has become the bottleneck of economic development. Magnesium alloys, especially Mg-A1 system, have been widely used as structural materials for automobiles to reduce weight. however, the dynamic mechanical properties of magnesium alloy have been studied rarely. It is a practical problem that researchers have not connected the dynamic mechanical properties of magnesium alloy with high-speed collision of the car. Therefore, the study of dynamic mechanical properties, fracture and failure mechanism of magnesium alloy can provide theoretical basis for safety design of magnesium alloy. The OM and SEM were used to analysis the microstructure evolution of Magnesium alloy welded joints after the high strain rate, the SHPB were used to study the dynamic deformation behavior of Magnesium alloy welded joints. The results shows that under different rain rate deformation，under two welding methods(TIG weldin