| The application rate of magnesium alloys in industry is increasing fiercely these years;especially it is most widely used in the automotive field.With the advent of lightweight vehicles and new energy vehicles,magnesium alloys have great market prospects as lightweight materials.Compared with AZ91D magnesium alloys,AM series magnesium alloys have better comprehensive performance,and their applications in the automotive field are constantly increasing.At present,the development of AM series magnesium alloys auto parts by enterprises and universities has become a hot topic,thus it’s necessary to promote further exploration and research on AM series magnesium alloys in all aspects of performance.This article has three parts research AM series magnesium alloy,the main research work as follows:By adjusting the content of Al and Mn in AM60 magnesium alloy,and study how they influence the casting fluidity properties,microstructure,mechanical properties and corrosion properties of as-cast alloys.The results show that the alloy Mg-6.4Al-0.4Mn with higher Al content and moderate Mn content has better casting flow properties,finer grains,better mechanical properties and higher corrosion resistance.Examining microstructure of high pressure die casting AM50+1Ce and AM60magnesium alloys,Vickers hardness testing,static tensile/compressive mechanical properties,dynamic tensile mechanical properties and fracture analysis.The results show that the structure of AM50+1Ce is uniform and the Vickers hardness distribution is uniform.The static tensile/compressionyield strength,tensile strength,and total elongation of AM50+1Ce magnesium alloy are 147 MPa（134 MPa）,262 MPa（356MPa）,21.9%（22.5%）,and the static tensile/compression yield strength,tensile strength and total elongation of AM60 magnesium alloy are 150 MPa（122 MPa）,254 MPa（344MPa）,14.5%（23.6%）,respectively.In addition,we can get the tensile and compressive asymmetry CYS/TYS were 0.91 and 0.81.However,AM60 magnesium alloy has a more pronounced variability effect and a stronger strain rate hardening.The static tensil/compressive fracture cracks both nucleate and grow at the casting defects such as shrinkage pores and pores in the alloy,then extend to the surface of the alloy.The tensile fracture morphology is typical characteristic of ductile and brittle fracture.The dynamic tensile fracture presents a mixed fracture mechanism impacted with multiple fracture mechanisms,the fracture of alloy changes from ductile to brittle fracture with the strain rate increasing.The open circuit potential and corrosion potential are more negative for die casting AM50+1Ce magnesium alloy in 3.5 wt.%NaCl solution,the corrosion current density is greater and the AC impedance is smaller,indicating that the electrochemical activity is higher than AM60.The average hydrogen evolution rates of die casting AM50+1Ce and AM60 magnesium alloys after immersing in 3.5 wt.%NaCl aqueous solution 132 h were7.58?10-3 mL·cm-2·h-1 and 6.59?10-3 mL·cm-2·h-1,respectively.The average corrosion weight loss rates of the two after immersing for 648 h were 8.34 mg·cm-2·h-1 and 9.16mg·cm-2·h-1,respectively,and the average annual corrosion rates were 0.422 mm/y and0.462 mm/y,respectively.The corrosion of die casting AM50+1Ce magnesium alloy in3.5 wt.%NaCl solution is more uniform,while the pitting corrosion of AM60 is more severe,and the mechanical properties should be influenced greater.The residual strength after 648 h soaking is 199 MPa and 183 MPa,respectively. |
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