For consumer products, commonly used alloy materials include aluminum alloy, zinc alloy and magnesium alloy. Titanium alloy is often used in the medical field due to its good biocompatibility. Today, let’s take a look at the characteristics of these alloy materials and make a comparison.
Of these four alloys, titanium alloy is the hardest and has the best strength. In terms of hardness, titanium alloy is much harder than the other three alloys. In terms of tensile strength, titanium alloy is stronger than zinc alloy, followed by magnesium alloy, and the lowest strength is aluminum alloy.
Strength and hardness comparison: Hardness: titanium alloy > zinc alloy > aluminum alloy > magnesium alloy Strength: titanium alloy > zinc alloy > magnesium alloy > aluminum alloy
However, for product structural design, weight also needs to be considered. If specific gravity is taken into account, zinc alloy has the lowest specific strength due to its highest density. Titanium alloy and magnesium alloy have high specific strength, but titanium alloy is expensive and has poor processability. Therefore, magnesium alloy is often used for structural parts that comprehensively consider weight and strength.
Aluminum alloy
The material composition is not listed here. The density of aluminum alloy is 2.63~2.85g/cm, with high strength (σb is 110~270MPa), specific strength close to high alloy steel, specific stiffness exceeds steel, good casting performance and plastic processing performance, good electrical and thermal conductivity, good corrosion resistance and weldability.
The fluidity of die-cast aluminum alloy is relatively good, and the melting point is 660℃. Aluminum alloy has the most abundant process application forms in product structure design, and the commonly used processing technologies are: die casting, extrusion molding, machining, stamping, and forging. Aluminum alloy profiles are widely used in building doors and windows, and aluminum profiles are also commonly used to build frames for mechanical equipment. There is also no shortage of aluminum alloys in the shells of electronic products and fast-moving consumer goods. The appearance requirements of such products are relatively high, and the more common processes are extrusion, machining, stamping, etc.
The shell of fast-moving consumer goods rarely uses die-cast aluminum, because die-cast aluminum alloy contains a high content of Si, so when doing Anodizing (anodizing), it directly reacts with the liquid medicine, and the surface effect after oxidation is relatively poor. Aluminum castings are often used for internal structural parts and parts with low requirements for appearance. The engine shell of a motorcycle requires a complex structure, which requires light weight and sufficient strength. Most of the rotating aluminum alloy die-casting is used as blanks.
Zinc alloy
Zinc alloy has low melting point, good fluidity and easy to weld. According to the manufacturing process, it can be divided into cast zinc alloy and deformed zinc alloy. Cast zinc alloy has good fluidity and corrosion resistance, and is suitable for die-casting instruments, automobile parts shells, etc. Deformed zinc alloy has good plasticity and ductility, and is mainly used as battery shells, printing plates, roof panels and daily hardware. The output of cast alloys is much greater than that of deformed alloys. For the structural parts of fast-moving consumer goods, deformed alloys are rarely used. Therefore, the following article only focuses on die-cast zinc alloys.
The density of zinc alloy is 6.3~6.7g/cm, the tensile strength σb is 280~440MPa, the melting point is low, it melts at 385℃, and it is easy to die-cast.
Zinc alloy has a high specific gravity, which is the largest among the four alloys described in this article. It also has the best fluidity and has good casting performance. It can die-cast complex and thin-walled precision parts, and the casting surface is smooth.
At room temperature, zinc alloy has good strength. It should be noted that zinc alloys should not be used in high and low temperature (below 0℃) working environments. Zinc alloys have good mechanical properties at room temperature. However, the tensile strength at high temperature and the impact performance at low temperature are significantly reduced. Zinc alloys have poor corrosion resistance. When the impurity elements lead, cadmium, and tin in the alloy composition exceed the standard, the castings will age and deform. Zinc alloy die castings have aging effects and aging phenomena, that is, the strength naturally decreases after a long time and becomes brittle. This is why many people complain that when replacing zinc alloy faucets, brittle fractures often occur, resulting in the faucet thread remaining in the water pipe and cannot be removed. Therefore, it is recommended that you try to choose copper faucets instead of zinc alloys when decorating.
At present, there are two major standard series used as castings internationally, one is ZAMAK alloy and the other is ZA series alloy. The ZAMAK alloys used are ZAMAK 2, ZAMAK 3, ZAMAK 5 and ZAMAK 7. (For the sake of simplicity, the above alloys are collectively referred to as alloys No. 2, No. 3, No. 5 and No. 7). The ZA series includes ZA-8, ZA-12, ZA-27 and ZA-35. ZA-8 is mainly used for hot chamber die casting, while ZA-12 and ZA-27 can only be used for cold chamber die casting due to special melting requirements. ZA-35 is generally used for gravity castings. The development of ZAMAK alloy preceded the development of ZA series alloys and is mainly used for pressure casting. The most widely used is zinc alloy No. 3.
ZAMAK 2: used for mechanical parts with special requirements for mechanical properties, high hardness requirements, good wear resistance, and general dimensional accuracy requirements.
ZAMAK 3: good fluidity and mechanical properties. Applied to castings with low requirements for mechanical strength, such as toys, lamps, decorations, and some electrical components.
ZAMAK 5: good fluidity and good mechanical properties. Applied to castings with certain requirements for mechanical strength, such as automotive accessories, electromechanical accessories, mechanical parts, and electrical components.
ZA8: It has good impact strength and dimensional stability, but poor fluidity. It is used for die-casting small-sized workpieces with high precision and mechanical strength requirements, such as electrical components.
Superloy: It has the best fluidity and is used for die-casting thin-walled, large-sized, high-precision, and complex-shaped workpieces, such as electrical components and their boxes.