Effect Of Modification On Conductivity Of Casting Al-Si-Mg Alloy

The status of Al-Si-Mg alloy research and it application in actual production weredescribed in the article. The factors that affect its electrical conductivity and reinforcementmethods were analyzed. The effect of modification on the mechanical properties andelectrical conductivity of cast aluminum alloy was also investigated.The chemical composition of the alloy is10wt%Si,0.3wt%Mg,0.2wt%Mn, and Al.Through modification treatment, it is expected to obtain optimal solution of complexmodification. Through observing the alloy microstructure as well as changes in mechanicalproperties and electrical conductivity, optimal modification treatment program is hopefullyto be obtained.The modification effort of Na salt is good with incubation period. The alloy has goodmodification effect when the heat preservation for5min. And it is better when for20min.But Na salt modification recession is serious. When it lasts for45min, the effort is worse.At the end of1hour, there is almost no modification effort. The effort of Sr is very goodbut the incubation is long. The good modification effort will appear when it lasts for1hour.Little effect on the hardness of the alloy has been brought through Sr modification becauseof their hydrogen storage, and it is improved by12.86%, tensile strength is reached154.31MPa, the same to the unmodified. But elongation is significantly enhanced to reachto11.3%. Conductivity is also increased more, at casting improved to37.6%IACS, T6states is raised to43.7%IACS. It has different modification effect between RE and Sr、Nasalt modification. The Si phase is changed into tiny flakes and α-Al is refined. Thehardness is improved32.94%, tensile strength is increased to161.08MPa and elongationrate is increased to9.4%. The grain refinement makes the electrical conductivity of thealloy declined to31.62%IACS, but after T6heat treatment the conductivity is significantlyenhanced to40.95%IACS.The experimental results show0.02wt%Sr+0.2wt%RE effect of modification isoptimal, and improvements of the mechanical properties and electrical conductivity are obvious. The group of modifier has a long-term nature, the time of metamorphism reachedabout6h long. The incubation period is short for0.5h below, and has good effect ofmodification, grain has been refined, the decreased velocity of density is slowed down withthe holding time, when modification time is for1h, the hardness of alloy is improved to35.48%compared with non-modification, tensile strength is improved to174.28MPa,elongation rate is improved to7.6%. After T6heat treatment, conductivity and mechanicalproperties of the alloy reached a higher level in the similar alloys, and the alloy can reachthe requirements ofAl-Si-Mg alloy for high strength conductors.