A kind of high-strength corrosion-resistant die-casting aluminum alloy and its die-casting method

Abstract

The invention provides high-strength corrosion-resisting die-cast aluminum alloy and a die-casting method thereof. The high-strength corrosion-resisting die-cast aluminum alloy comprises the followingingredients in percentage by mass: 9.6 to 10.4 percent of Si, 0.4 to 0.6 percent of Mg, 0.3 to 0.5 percent of Fe, 0.1 to 0.3 percent of Ti, 0.01 to 0.03 percent of Tc, 0.002 to 0.006 percent of B, 0.01 to 0.03 percent of Ba, 0.005 to 0.015 percent of Ge and the balance of Al and inevitable impurities. The die-casting method of the high-strength corrosion-resisting die-cast aluminum alloy comprises the following steps: preparing materials; smelting aluminum alloy liquid; refining, degassing and deslagging; adding a grain refiner, an iron-rich phase modifier and a silicon phase modifier; stirring and performing die-casting formation. According to the die-casting method provided by the invention, main alloy elements Si and Mg are optimized, and moreover a modified Fe-rich phase, a co-crystallized Si phase and a primary Si phase are refined by means of micro-alloying treatment, so that the strength and plasticity of the die-cast aluminum alloy are improved. The die-cast aluminum alloy provided by the invention is applicable to die-casting formation of various aluminum alloy components and parts which have relatively high requirements on strength, plasticity and corrosion resistance.

Description

Technical field [0001] The invention belongs to the field of aluminum alloy die-casting, and particularly relates to a high-strength corrosion-resistant die-cast aluminum alloy and a die-casting method thereof. Background technique [0002] Al-Si-Mg die-casting aluminum alloy belongs to hypoeutectic aluminum-silicon alloy. Because it does not contain Cu element, it has excellent corrosion resistance and better thermal crack resistance, air tightness and fluidity. It is widely used It is suitable for the thin-walled die-casting parts with low load and complex shape, such as various instrument housings, automobile casings, gearbox oil pump housings, wheel covers, motorcycle crankcases, bicycle wheels, etc. With the development of lightweight vehicles such as automobiles and motorcycles, aluminum alloy die-casting parts continue to develop thinner, which requires die-cast aluminum alloy to have higher strength and shape. Although the existing Al-Si-Mg die-cast aluminum alloy has ex...

AI Technical Summary

Problems solved by technology

Although the existing Al-Si-Mg series die-casting aluminum alloys have excellent corrosion resistance, good thermal cracking resistance, air tightness and fluidity, the problems of generally low strength and poor shaping have become increasingly prominent , which greatly limits the application of Al-Si-Mg die-casting aluminum alloys

[0003] The reason for the low strength and poor plasticity of the existing Al-Si-Mg series die-casting aluminum alloys is that the Fe content of the die-casting aluminum alloy is high, and Fe is usually in the form of thick needle-shaped Al-Fe-Si series The Fe-rich phase exists in the aluminum alloy matrix. This coarse needle-shaped Fe-rich phase itself is a hard and brittle intermetallic compound phase, which will severely split the aluminum matrix and become the crack source and crack propagation direction of the aluminum alloy fracture.

Secondly, although the Al-Si-Mg die-casting aluminum alloy belongs to the hypoeutectic aluminum-silicon alloy, the Si content is relatively high. In addition to the presence of Si in the form of acicular eutectic Si in the aluminum alloy, a small part of Si is in the form of coarse The massive primary Si exists in the form of acicular eutectic Si and the coarse massive primary Si phase are both hard and brittle phases, which will also severely split the aluminum matrix and reduce the strength and plasticity of the aluminum alloy.

Therefore, the existing Al-Si-Mg series die-casting aluminum alloys and their die-casting methods still need to be improved and developed.