AZ31镁合金、5083铝合金焊接工艺及接头力学性能研究

大连交通大学工学硕士学位论文AbstractAluminum alloy has been widely used in the rail transportation equipment.With thespeeding-up of the train track,the demands of modern rail equipment lightweight arecontinually increasing.Recently,fusion welding technique is still the main dominantconnection technology in rail trains at China,but the aluminum alloy bodywork weldingprocess stability are still problems,when there are fluctuations in the quality,seriously affectthe pass rate,caused some difficulties in the development of lightweight trains.Looking for anew alternative technologies and lighter materials become the new exploration target.However,magnesium alloy is known as the 21st century green structural materials with highspecific strength,stiffness,renewable cycle and a series of advantages.Magnesium alloy hasbeen widely used in the aerospace,automotive,3C,and other fields.But the tracktransportation equipment has just started.Therefore,it is necessary to adopt a new weldingmethod alternative to fusion welding technology;comparative study of the safety andreliability of magnesium alloy welded joints with rail transit vehicles commonly usedaluminum alloy welded joint.In this paper,the AZ31 magnesium alloy and rail transit train commonly used aluminumalloy 5083 is the studying materials.Studying the FSW and MIG welded joints mechanicalproperties,FSW welded joints fatigue behavior,and Welding life cycle cost evaluationanalysis.Reached the following conclusions:The test results show that the mechanical properties of the FSW welding technology canreplace MIG welding technology for the safety of the welded joints of AZ31 magnesium alloyand aluminum alloy 5083-H111 welding process.5083-H111 FSW welded joints reliabilitybetter than AZ31 magnesium alloy.The mechanical properties of 6mm rolled AZ31magnesium alloy plate FSW welded joints at the rotation speed of 1200 r/min and the weldingspeed of 100 mm/min is better than other welding parameters.Its tensile strength is 240MPaand reached 92.3%to the base metal.The mechanical properties of 6mm rolled 5083-H111aluminum alloy plate FSW welded joints at the rotation speed of 800 r/min and the weldingspeed of 200 mm/min is better than other welding parameters.Its tensile strength of 318MPaand reached the base metal of 99.4%.The fatigue test results of 5083-H111 aluminum alloy and AZ31 magnesium alloy plateFSW comparatively good welded joints show that the fatigue strength is better equivalent tothe parent material approximately 135MPa and 110MPa.Magnesium alloy is more sensitiveto loading stress.As the stress level increases,the fatigue life dropt rapidly.It's found that thefatigue strips of magnesium alloy are wider than aluminum alloy.The fatigue strips ofmagnesium alloy are brittle.The fatigue strips of aluminum alloy are toughness.Analysis of