Increasing of founding properties of secondary aluminium alloys

• Main Author: O.V. Lyutova
• Format: Article
• Language: English
• Published: Dnipro National University of Railway Transport named after Academician V. Lazaryan 2013-06-01
• Series: Nauka ta progres transportu
• Subjects: secondary aluminum alloys; liquidity; linear shrinkage; porosity; modifier
• Online Access: http://stp.diit.edu.ua/article/view/14542/14184

Purpose. To study the influence of metallurgical factors of production on casting properties of secondary aluminum alloy АК9М2. Methodology. For the experimental melts shaving amount in a charge, iron content and the quantity of modifier additive were chosen as independent variables. The components of modifier were being changed in the intervals of 25…40 % Na2CO3, 12…20 % SiC, 3…8 % Ti, the other – S. The microstructure of alloys was investigated under a light microscope, using the method of quantitative metallography. Influence analysis of certain parameters of alloys was conducted by mathematical statistics methods. The influence of shaving additions, iron and modifier amount on liquidity and porosity of the resulting alloys was studied. Findings. The paper shows that the increase of shaving content in the charge from 1 to 19 % and iron content in alloy from 0.66 to 2.34 % resulted in the decline of alloy liquidity on 30…35 %. Simultaneously the linear shrinkage reduction for 18…20 % and the porosity increase from 0.5 to 2.5 points were observed. The presented changes of alloy casting properties are conditioned by the amount of intermetallic phases of unfavorable form and its capacity for aeration. Increase of modifier additive from 0.02 to 0.15 % resulted in the liquidity increase on 10…15 %, the increase of linear shrinkage on 30…35 % and porosity decline from 2.5 to 0.5 points. At the same time a change of form of intermetallic phases and increase of their evenness were observed. Originality. The increase of iron concentration in silumin composition is accompanied by the decline of its liquidity. Thus, the rate of decline of alloy liquidity is proportional to the amount of dissolved iron. The character of iron influence is caused by formation of high temperature intermetallic compounds of the type Al3Fe, Al5SiFe, which promote the metal viscidity. Practical value. Practical use of the obtained scientific results would develop the technical solutions oriented to the quality indicator increase of silumin alloy.