Study On The Microstructure And Properties Of Al-Mg-Si Multicomponent Aluminum Alloy Used For Autombile Swing Arm

With the development of modern automobiles industry,high requirement of performance of auto pars have been put forward.Aluminum alloy serves as the main structural components of automobiles,and the automobiles life and driving safety has close relationship with their properties.Al-Mg-Si aluminum alloys has been widely applied as auto pars component,because of the excellent characteristics,such as high specific strength,good machinability,and so on.So this paper makes research on the microstructure of Al-Mg-Si aluminum alloys under certain technological conditions;Improving its organization,and the mechanical properties of materials,have a great significance to meet the needs of practical engineering.This paper,takes the Al-Mg-Si multi aluminum alloys used in automobile swing arms as the study object,and with aids of metallographic microscope,scanning electron microscope,tensile testing machine and other analysis methods,the relationship of microstructure and property was discussed,especially the effects of solid solution and aging treatment on the microstructure and properties of the alloys during heat treatment.The main results and conclusions are summarized as follows:1.The microstructure of as cast alloy rods was thick,and the distribution of intermetallic compounds at grain boundaries.The microstructure of the samples were refined after extrusion,and the intermetallic compounds are broken and distributed along a certain direction.So in order to improve the performance of the organization,it's necessary to heat treatment.2.Firstly,the alloys were treated with solid solution at different temperatures.The results show that,the Mg₂Si phase dissolves into the matrix gradually and the?-?AlMnFeSi?mixed phase is retained with the solution temperature rising and solution time prolonging.And the alloy's tensile strength,brinell hardnes and microhardness all increase firstly and then decreasing.However,the lower or higher solution temperature will cause the growth of grains,thus resulting in the property deterioration.The over temperature sensitivity of the alloy is 570?,the appropriate solution process is 530?×4h.3.Subsequently,the aging treatment of aluminum alloys after solid solution treatment under different parameters were carried out.Al-Mg-Si aluminum alloy has a significant effect of aging precipitation strengthening.When the aging temperature is below 190?,along with the aging temperature rising and aging time prolonging,thetensile strength,brinell hardnes and microhardness of the alloy increase at first and then decrease gradually.When the aging temperature is higher than 190?,with the increase of aging temperature,the speed of aging strengthening accelerate,the shorter time to reach the maximum reinforcement effect.The appropriate artificial aging process parameter:170 ? × 10 h,at which the tensile strengthen is 372 MPa,the elongation is 12.17%,the hardness is 104 HB and the Vickers hardness is 111.4HV.4.The fracture toughness of T6 alloy is ductile fracture.When the aging temperature is too high,the fracture mode of the alloy shows the characteristics of ductile fracture and brittle phase.The coarse second phase at the bottom of the dimples are rich in Fe of the ?-?Al MnFeSi?mixed phase and small number of Mg₂Si strengthening phase,due to the presence of Fe rich inclusions,the brittleness of the alloy increase,which is harmful to its plasticity and toughness of the alloy.