Improvement of Al-20%Sn Microstructure by Using New Rheocasting Process
journal of kerbala university,
2007, Volume 3, Issue 3, Pages 307-319
AbstractNew Rheocasting process is used to produce Al-20%Sn alloy for modernity of this alloy and its potential importance in industry, particularly the parts that need high wear resistance. A casting of dimensions 6x6x12 cm was chosen, having V/A ratio of 1.2 and mould inclination of 75º.The casting produced at different pouring temperatures ranging from Tm+10-50.The cooling was done from different temperatures within the freezing rang of the alloy between liquidus and solidus lines, to study the effect of their variables on the shape and size of grains. The microstructure shows the possibility of producing equiaxial grains along the cross section of the casting when the pouring temperature was 640ºC and cooling at 550ºC. The decreasing in the pouring and cooling temperatures helped to increase the refining degree of the grains to approach the equiaxid shape .The average size of the grains was 45 μm while the average volume fraction for the primary phase was 0.662-0.656 .The hardness test showed the casting produced by new rheocasting achieve higher hardness values of 37HB in comparison with gravity die castings refined by using Al–10Ti. This work appearances the development in ultimate tensile stress and elongation of the castings which achieved by new rheocasting processes (UTS 108 MPa & 13% Elongation) comparing to gravity casting (UTS 95 MPa & 8% Elongation).
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