Al-Mg alloy The performance characteristics of Al-Mg al […]
The performance characteristics of Al-Mg aluminum alloys are: good room temperature mechanical properties; strong corrosion resistance; relatively poor casting properties, large fluctuations in mechanical properties, and wall thickness effects; long-term use, the plasticity of alloys due to aging effects. Decline, and even the phenomenon of cracking Die Casting; die castings have a greater tendency to stress corrosion cracking. The disadvantages of the Al-Mg alloy partially offset its advantages, making it somewhat limited in its application.
Al-Zn aluminum alloy die-casting can obtain higher mechanical properties after natural aging. When the mass fraction of zinc is more than 10%, the strength is significantly improved. The disadvantage of this alloy is its poor corrosion resistance, its tendency to stress corrosion, and its tendency to crack during die casting. The commonly used Y401 alloy has good fluidity and is easy to fill the cavity. The disadvantage is that the formation of pores has a large tendency. When the content of silicon and iron is small, it is easy to crack.
Al-Si alloyBecause Al-Si aluminum alloy has the characteristics of small crystallization temperature interval, large latent heat of solidification and large specific heat capacity of the silicon phase in the alloy, and relatively small coefficient of linear shrinkage, its casting performance is generally better than other aluminum alloys. Its filling capacity is also good, and the tendency of hot cracking and shrinkage is also relatively small. The Al-Si eutectic contains the least amount of brittle phase (silicon phase), with a mass fraction of only about 10%, so its plasticity is better than that of other aluminum alloy eutectics, and the remaining brittle phase can be further processed by modification. Improve plasticity. The test also shows that the Al-Si eutectic maintains good plasticity near its freezing point, which is not found in other aluminum alloys. Casting alloys often have a considerable amount of eutectic in order to ensure good casting performance; an increase in the number of eutectic alloys will make the alloy brittle and reduce the mechanical properties, there is a certain contradiction between the two. However, due to the good plasticity of Al-Si eutectic, both the mechanical properties and the casting properties can be satisfied. Therefore, Al-Si alloy is currently the most widely used die-cast aluminum alloy.