| Aluminum alloy has been widely used in the rail transportation equipment. With the speeding-up of the train track, the demands of modern rail equipment lightweight are continually increasing. Recently, fusion welding technique is still the main dominant connection technology in rail trains at China, but the aluminum alloy bodywork welding process stability are still problems, when there are fluctuations in the quality, seriously affect the pass rate, caused some difficulties in the development of lightweight trains. Looking for a new alternative technologies and lighter materials become the new exploration target. However, magnesium alloy is known as the21st century green structural materials with high specific strength, stiffness, renewable cycle and a series of advantages. Magnesium alloy has been widely used in the aerospace, automotive.3C. and other fields. But the track transportation equipment has just started. Therefore, it is necessary to adopt a new welding method alternative to fusion welding technology; comparative study of the safety and reliability of magnesium alloy welded joints with rail transit vehicles commonly used aluminum alloy welded joint.In this paper, the AZ31magnesium alloy and rail transit train commonly used aluminum alloy5083is the studying materials. Studying the FSW and MIG welded joints mechanical properties. FSW welded joints fatigue behavior, and Welding life cycle cost evaluation analysis. Reached the following conclusions:The test results show that the mechanical properties of the FSW welding technology can replace MIG welding technology for the safety of the welded joints of AZ31magnesium alloy and aluminum alloy5083-H111welding process.5083-H111FSW welded joints reliability better than AZ31magnesium alloy. The mechanical properties of6mm rolled AZ31magnesium alloy plate FSW welded joints at the rotation speed of1200r/min and the welding speed of100mm/min is better than other welding parameters. Its tensile strength is240MPa and reached92.3%to the base metal. The mechanical properties of6mm rolled5083-H111aluminum alloy plate FSW welded joints at the rotation speed of800r/min and the welding speed of200mm/min is better than other welding parameters. Its tensile strength of318MPa and reached the base metal of99.4%.The fatigue test results of5083-H111aluminum alloy and AZ31magnesium alloy plate FSW comparatively good welded joints show that the fatigue strength is better equivalent to the parent material approximately135MPa and HOMPa. Magnesium alloy is more sensitive to loading stress. As the stress level increases, the fatigue life dropt rapidly. It’s found that the fatigue strips of magnesium alloy are wider than aluminum alloy. The fatigue strips of magnesium alloy are brittle. The fatigue strips of aluminum alloy are toughness. Analysis of fatigue fracture found that the second-phase particles near or at the surface easy to become a fatigue source. State of high stress levels can find many fatigue sources.This paper defines the welding cycle cost (WCC), established the welding cycle cost evaluation model (WCCA). What an example to AZ31magnesium alloy and5083-H111aluminum alloy welding for cost and reliability evaluation. The results show that:FSW can substitute MIG welding applied to track trains.5083-H111aluminum alloy welded joint is more secure than AZ31magnesium alloy. AZ31sheet can substitute5083-H111sheet applicant on the track when its strength can satisfy the design request. |
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