Preliminary Study On Integrated Calculation Of ZL201 Cast Aluminum Alloy Subframe

Automotive lightweight puts forward higher requirements for the comprehensive performance of sub-frame.The development trend of aluminum alloy sub-frame casting is mainly shown in three aspects,which are large-scale integration,strengthening and toughening and complex refinement.The advantages of ZL201 include low density and excellent corrosion resistance.It is used high strength castings in the manufacture.However,the poor fluidity leads to the problems by incomplete filling and hot cracking in the casting process.Based on integrated computing,the theoretical calculation is combined with the gold experimentgroup.The relationship between the“technology-microstructure-properties”for cast aluminum alloy is described quantitatively.The the process of casting defects is soluted,and the comprehensive performance is improved in ZL201 aluminum alloy castings.In this paper,three modules include alloy design,casting process and result validation,and the modules were described as follows:?1?Al,Cu,Mn and Ti were added into ZL201 cast aluminum alloy.Firstly,the binary alloys were analyzed with phase precipitation and the growth patterns of grain.Based on the simplest composition,the basic parameters were provided for the establishment of prediction model.Secondly,the nucleation sites of ternary alloys were determined by the experimental simulation results of binary system.Finally,the reasonable simulation parameters were applied to ZL201model,and the accuracy of simulation results was verified by experiments.The phase composition and phase content of ZL201 aluminum alloy were characterized by XRD,SEM and metallography.According to the phase structure characterization and theoretical calculation verification analysis,the results showed that e main alloy phases of ZL201 were Al₃Ti,?and Al-Cu-Mn phases.In the Al-5.0wt%Cu,Al-0.8wt%Mn,and Al-0.3wt%Ti binary alloy,the precipitation temperature of Al₃Ti was 742.8?,?phase was 548.6?,and the Al₆Mn was663.4?.In the Al-5.0wt%Cu-0.8wt%Mn and Al-5.0wt%Cu-0.3wt%Ti binary alloy,the precipitation temperature of?phase was not changed,the Al₃Ti was 652.4?,and the Al-Cu-Mn was 622.5?.A part of the Cu was dissolved with?-Al,and the solid solution phase increased the free energy and reduced the precipitation temperature for alloy system.At the z=0 surface,the growth patterns were dominated by Al-Cu,and the microstructure was a regular ribbed morphology.?2?The effects of different Cu contents on ZL201 cast aluminum alloy were studied by integrated computing.The elastic modulus,poisson's ratio and tensile strength of cast aluminum alloy were calculated by Pro CAST.The mechanical properties of ZL201 aluminum alloy sub-frame casting were characterized by nano-indentation.The mechanical properties of ZL201aluminum alloy tensile specimen and subframe casting were tested by tensile test.The results showed that the precipitation of the?phase was most obvious when the Cu content was 5.4wt%.Effects of Cu were most significant on mechanical properties and microstructure.The?strengthening phase was by formed by Al and Cu.The?phase improved tensile strength,yield strength,elastic modulus and other mechanical properties.The mechanical properties of Al5.0Cu0.8Mn0.2Ti tensile samples were significantly improved by heat treatment.The tensile strength was 221.74Mpa,the elongation was 4.77,the yield strength was 100.67Mpa,and the elastic modulus was 91.43Mpa.?3?ZL201 aluminum alloy sub-frame castings were prepared by sand mold gravity casting and metal mold low pressure casting.The process parameters were optimized by the theoretical modeling.The results showed that the optimum process parameters of gravity sand mold casting were as follows:the mold temperature was 250?,the casting temperature was 700?,and the casting time was 24s.The optimum process parameters of gravity sand mold casting were as follows:the mold temperature was 250?,the casting temperature was 720?and the pressure was 0.45Mpa.