한국주조공학회

The effects of Mg and Si contents on the microstructure and mechanical properties in Al-Mg alloy (ALDC6) were investigated. The results showed that phase fraction and size of Mg2Si and Al15(Fe,Mn)3Si2 phase in the microstructure of Al-Mg alloy were increased as the Mg and Si contents were raised from 2.5 to 3.5 wt%. With Si content of 1.5 wt%, freezing range of the alloy was significantly reduced and solidification became more complex during the final stage of solidification. While there was no significant influence of Mg contents on mechanical properties, Si contents up to 1.5 wt%, strongly affected the mechanical properties. Especially elongation was reduced by about a half with more than 1.0 wt%Si in the alloy. The bending and impact strength were decreased with increased amount of Si in the alloy, as well. The lowered mechanical properties are because of the growth of particle shaped coarse Mg2Si phase and precipitation of the needle like β-AlFeSi in the microstructure at the last region to solidify due to presence of excess amount of Si in the alloy.

Al-Mg alloy, Die casting, Mechanical property, Microstructure, Thermodynamic simulation, Alloying element effect