Composition Design And Die-Casting Simulation Of Anodized Al-Mn-Mg Die-Casting Aluminum Alloy

Using die-casting technology to produce thin-walled 3C product shells can effectively improve production capacity,conserve energy and reduce emissions,which has significant economic and social benefits.Aluminum alloys with high fluidity(e.g.Al-Si alloys)is the key to produce thin-walled shells by die-casing.However,the Al-Si alloys cannot perform the decorative anodization required by exterior parts.As a eutectic alloy,Al-2Mn has good fluidity,and its anodic oxidation performance is much better than traditional die-casting aluminum alloys,which is a potential foundation system for the development of anodized die-cast aluminum alloy.Therefore,in this paper,the composition design on the basis of Al-2Mn alloy is carried out to study the influence of main additive element Mg and trace element Sc/Y on the fluidity,mechanical properties and anodic oxidation properties of the alloy,finally,the thin-wall die-casting molding capacity of the new alloy was verified with the help of numerical simulation software.The results are as follows:(1)After adding Mg,the solidification range and melt viscosity of the alloy increase significantly,the flow length of Al-2Mn-x Mg alloys decreases monotonously with the increase of Mg content.When Mg addition is less than 1.0 wt.%,the alloy's fluidity still maintain above 75% of ADC12.Due to solution strengthening and fine grain strengthening,the mechanical properties of Al-2Mn alloy are significantly improved after the addition of Mg.its yield strength,ultimate tensile strength and elongation increase with the increase of Mg content,the ultimate tensile strength of Al-2Mn-1Mg alloy reached 161.5 MPa,an increase of 49.5%.After anodizing,Al-2Mn-x Mg alloy can form a dense and uniform porous structure,and the dyeing effect is better.But when Mg content beyond 1.0 wt.%,the corrosion pit defects in the film layer increase,which will affect the roughness and corrosion resistance of the film.(2)Based on Al-2Mn-1Mg,Sc/Y was added to improve the properties of the alloy.After adding Sc and Y,the fluidity of the alloy is improved,the fluidity of Al-2Mn-1Mg-Sc/Y alloy reaches more than 80% of ADC12.Sc and Y are conducive to the improvement of mechanical properties,of which Sc has the most significant effect,the alloy tensile strength reached 208.2 MPa after adding 0.3 wt.% Sc alone,while the tensile strength of the alloy with Sc/Y composite addition is also more than 200 MPa.After adding Sc/Y,the micro-morphology of the alloy's anodic oxidation film did not change significantly,the coloring effect of the film layer was good,and the corrosion resistance was improved.(3)Based on Al-Mn-Mg die-casting aluminum alloy,a three-factor three-level orthogonal simulation experimen was designed to optimize die-casting process,and the optimal parameters was determined: injection speed is 3.5 m/s,die-casting temperature is 680 ?,the mold temperature is 200 ?.Under this process,the liquid filling of the alloy is stable,defects such as gas entrainment,cold partition and insufficient pouring cannot found,and the temperature field distribution during solidification is reasonable,the shrinkage defects were reduced.The final die-casting trial results are basically consistent with the mold flow analysis results,which shows that the new Al-Mn-Mg aluminum alloy can be adapted to high-pressure die casting with a minimum wall thickness of 0.6 mm.