Heat treatment method for Al-Si-Cu-Mg casting alloy

Abstract

The invention relates to Al-Si-Cu-Mg casting alloy. The Al-Si-Cu-Mg casting alloy is formed by smelting electrolytic aluminum, silicon metal, pure magnesium and Al-Cu intermediate alloy and comprises, by weight, 5.5%-6.5% of Si, 1.8%-2.2% of Cu, 0.45%-0.55% of Mg and the balance Al, and the ratio of the Cu to the Mg is 4:1. The Al-Si-Cu-Mg casting alloy is subjected to two-stage solid solution treatment and two-stage aging treatment, it can be ensured that precipitated phases of the Al-Si-Cu-Mg casting alloy are all dissolved in a matrix through suitable solid solution temperature and time, and overburning of crystal boundaries cannot be caused; and then the characteristics and mechanical properties precipitated by the alloy phases are controlled through two-stage aging treatment, so that the tensile property of the Al-Si-Cu-Mg casting alloy obtained through the method is obviously improved in index compared with the tensile property of Al-Si-Cu-Mg casting alloy subjected to T6 treatment.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a heat treatment method for an Al-Si-Cu-Mg casting alloy. Background technique [0002] The typical heat treatment method for Al-Si alloy used in sand mold and gravity casting is T6 heat treatment, which mainly includes: [0003] 1. Solid solution treatment is carried out at a higher temperature to dissolve the formed Cu-rich and Mg-rich phase particles to obtain a highly uniform alloy composition. [0004] 2. Quenching treatment. Generally, quenching at room temperature is used to obtain a supersaturated solid solution of solid solution atoms and vacancies. [0005] 3. Age hardening treatment, at room temperature (natural aging) or elevated temperature (artificial aging), the strengthening phase is precipitated from the supersaturated solid solution. [0006] The temperature of solution treatment is generally selected close to the eutectic point temperature of the alloy, wh...

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Problems solved by technology

However, if the solid solution temperature is too high, it will lead to local over-burning of the alloy, and the mechanical properties of the alloy will drop sharply. Gradually, this contradiction has escalated into a barrier in the industry, so for Al-Si-Cu-Mg The ratio of element selection and the temperature and time parameters used for the corresponding two-stage solid solution and two-stage aging have become the main focus of alloy producers to improve product quality and save production costs.

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