Research Of The Fluidity And Mechanical Properties On Anodized Al-Mn Casting Aluminum Alloy

Aluminum alloy has low density and high specific strength,it is widely used in the industry of information appliances(3C products),automobile parts and other fileds.At present,3C products are mainly produced by the aluminum alloy which has excellent anodized properties.But the processing efficiency and raw material utilization ratio is relatively low when using the CNC method.Casting has the characteristics of high efficiency and high material utilization,but there is no casting aluminum alloy with excellent anodizing performance.Therefore,the development of anodized casting aluminum alloy has become an urgent demand in the field of 3C products.Fluidity is the main influence factor of alloy casting property.Therefore,Mn and Co was chosen as the research subject,because they can get a good solidify range when the elment content is relatively low.The results of fluidity and microstructure observation showed that when Mn content was between 0.6~2.7 wt.%,the fluidity of Al-Mn binary alloy increased first and then decreased with the increase of Mn content.The fluidity of Al-1.9Mn alloy was the 90% of ADC12 aluminum alloy,and Mn was mainly dissolved in aluminum.When the content of Mn increased to 2.7 wt.%,a large number of Al-Mn primary phases formed during the solidification of the alloy,the fluidity decreased.In Al-Mn-Co alloy,Co was hard to dissolve in aluminum and mainly existed in the form of the second phase.The fluidity of the alloy decreased with the increase of Co content.Thermal analysis results showed that the addition of Mn and Co can prolong the eutectic reaction time,reduce the solidification interval and dendrite coherency temperature,fluidity can be improved in the theory.But in the alloy solidification process,Mn and Co existed in different forms,so the change trend of the fluidity of the alloy was different in Al-Mn and Al-Mn-Co alloy.Inspired by the national standard 6-series aluminum alloy,Mg and Si can effectively improve the strength of aluminum alloy,but will not deteriorate the anodization of aluminum alloy.Therefore,we tried to add Mg and Si elements in Al-Mn alloy.The results showed that whether add the Mg and Si alone,or add Mg/Si at the same time,the eutectic reaction platform will shorten and the solidification interval will increase,resulting in the decrease of fluidity of alloy.In addition,when the total alloy element was less than 3%,the tensile strength of the alloy reacheed 196 MPa,which was 72% higher than that of Al-1.9Mn.In order to verify the anodizing performance of the casting aluminum alloy,the thickness,microstructure and color uniformity data of Al-Mn-Mg-Si alloy after anodizing were analyzed.The results showed that when the content of Mg/Si was between 0.28 wt.% and 0.84 wt.%,the thickness of oxide film of Al-Mn-Mg-Si alloy changed between 12~13 μm,the film layer was continuous and uniform,and formed clear porous structure.In addition,the film was white and bright,which had little influence on the subsequent coloring treatment.