| In view of the shortcomings that low room temperature strength and poor plastic in the research status of magnesium alloy,based on the research of AZ80 magnesium alloy,this paper improved the integrated mechanical properties of AZ80 magnesium alloy by using the methods that micro-alloying(included the alloying of single element Nd,and the alloying of complex elements Nd,Sn),solution ageing treatment,rolling plastic deformation,annealing treatment and so on.The influence of alloying element,rolling and annealing process on the microstructure evolution and mechanical properties of AZ80 magnesium alloy was also studied,and this paper had obtained a kind of alloy composition with excellent comprehensive properties finally.The results show that:(1)Respectively adding rare-earth element Nd can significantly refine coarse β-Mg17Al12 phase in the as-cast structure of AZ80 magnesium alloy.When addition amount of Nd is 0.6wt.%,the β with tiny dispersion distribution is combined with the rare earth phase together,and the tensile strength of as-cast alloy is up to 200 Mpa,the elongation is 7.67%.In the aging treatment,the Nd element has the effect of inhibiting the precipitation of the β-Mg17Al12 phase in the discontinuous precipitation of the lamellar layer,and prolonging the time required for the alloy to reach the peak aging.The tensile strength of aging AZ80-0.6% Nd alloy is up to 221 MPa and the elongation is 4.1%.(2)The Sn element with different content is compounded when addition amount of fixed Sn is 0.6wt.%.While the Sn element is added in an amount of 1.0 wt.%,the solid solution strengthening effect of the Sn is remarkable,and the tensile strength of alloy is up to 204 MPa,the elongation is 7.3%.In the treatment of T6,when the content of Sn is 1.0wt.%,the non-continuous precipitation of β-Mg17Al12 precipitated with elongated strip firstly;When the content of Sn is 2.0wt.%,the Mg2 Sn particles precipitate firstly,and the morphology of the precipitated non-continuous precipitated β-Mg17Al12 phase is affected.The β-Mg17Al12 phase has a short rod shape,and the higher content of Sn has the effect of non-continuous precipitation during aging.The tensile strength and yield strength of AZ80-0.6% Nd-1.0% Sn alloy are 241 MPa and 185 MPa respectively,and the elongation is 4.8%.(3)In the multi-pass and small deformation of the rolling process,the alloy structure consists of a large number of twins and a small amount of dynamic recrystallization.With the increase of Sn content,the tensile strength of the alloy increases firstly and then decreases,and the elongation of alloy decreases gradually.When the Sn content is 1.0wt.%,the tensile strength of alloy reaches a maximum of 345 MPa and the elongation is 4.9%.When the annealing temperature is 380℃ and AZ80-0.6% Nd-1.0% Sn alloy is annealed for 15 min,the original twins of the alloy almost completely occur the static recovery and recrystallization process,resulting in a small equiaxial new grain;When the AZ80-0.6% Nd-1.5% Sn alloy is annealed for 15 min,the static recovery and recrystallization process has been completed for some time,and some new grains have grown.With the increase of annealing time,the tensile strength of the two kinds of experimental alloys decrease gradually,and the elongation increase first and then decrease.After 15 min of annealing,the tensile strength of the two experimental alloys is 315 MPa and 293 MPa respectively,and the elongation is 11.2% and 9.3% respectively.After annealing for 30 min,the tensile strength of the two experimental alloys decreased by about 70 MPa. |
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