Hypereutectic cast aluminum-silicon alloy modification method

Abstract

The invention discloses a hypereutectic cast aluminum-silicon alloy modification method. The method comprises the following steps that material preparation is prepared with the following elements of,by mass, 6.000%-12.600% of Si, 0.001%-0.150% of Sr, 0.020%-0.122% of La or RE, 0.001%-0.150% of B, and the balance Al, wherein the mass ratio of the Sr to the B is not larger than 1.351, the mass ratio of the La to the B or the RE to the B is within 1-5, then smelting and casting are conducted through the processes of melting, refining and degassing, feeding and heat preservation casting to obtainan aluminum-silicon alloy, wherein the modification grade is 4-6 grades, and the modification period is 2-3 hours. According to the method disclosed, the total feeding amount of the Sr, the La and the B is reduced by 62.3%-72.5%, the sum of the mass fractions of the modified elements is only 0.022%-0.237%, that the production time is shortened by 37.5%-52.0%, and only reaches 60-100 minutes, andthe method has extremely high economic value.

Description

technical field [0001] The invention relates to a preparation method of Al-Si casting alloy, in particular to a chemical modification treatment method of Al-Si casting alloy, which is applied in the technical field of aluminum alloy smelting. Background technique [0002] For hypoeutectic Al-Si casting alloys, the mechanical properties of castings, especially the elongation, are obviously affected by the shape, size and distribution of eutectic silicon. For cast aluminum-silicon alloys with a silicon mass fraction greater than 6%, modification must be carried out. Usually The chemical modification method is used to modify the hypoeutectic cast aluminum-silicon alloy, that is, the purpose of changing the morphology and size of the eutectic silicon phase is achieved by adding a modification agent to it. Commercial hypoeutectic Al-Si alloy modifiers mainly include Na salt modifiers and Al-Sr master alloy modifiers. Sr-containing modifiers are more environmentally friendly and h...

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Problems solved by technology

[0006] 3. The existing technology does not conduct relevant research on whether the addition of the rare earth element La can achieve synergistic effect with Sr to improve the metamorphic effect without damaging the grain refinement effect, which limits the application occasions of this technology;

[0007] 4. According to the applicant's recent research, the influence of Sr, La, and B mass fractions on the effect of modification and grain refinement is only a superficial phenomenon, and the real decisive factors are the mass ratio of Sr / B and La / B or RE / B mass ratio, the prior art does not provide this technical feature, and no relevant research has been carried out

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