Comparison Of Aluminum Alloy, Zinc Alloy, Magnesium Alloy, And Titanium Alloy

With the improvement of people's quality of life, the requirements for product aesthetics and quality are constantly improving. More and more consumer products are made of alloy materials. Metal materials give people a sense of high-end, sturdy, and durable quality, while traditional plastic shell products are gradually being labeled "cheap" and "low quality" in consumers' hearts.

For consumer products, commonly used alloy materials are aluminum alloys, zinc alloys, and magnesium alloys. Titanium alloys are commonly used in the medical field due to their good biological compatibility. Fang Gong will take a look at the characteristics of these alloy materials and make a comparison.

Therefore, the inductive summary is placed first, see the following performance comparison table.

Physical performance comparison table

Of these four alloys, titanium alloys are the hardest and have the best strength. In terms of hardness, titanium alloys are far harder than the other three alloys. In terms of tensile strength, titanium alloys are stronger than zinc alloys, followed by magnesium alloys, and aluminum alloys have the lowest strength.

Strength and hardness comparison

However, in terms of product structure design, weight also needs to be considered. If the specific gravity is taken into consideration, the zinc alloy has the largest density but the smallest specific strength. Titanium alloys and magnesium alloys have higher specific strengths, but titanium alloys are expensive and poor in workability. Therefore, magnesium alloys are mostly used in structural parts that must comprehensively consider weight and strength.

Aluminum alloy

Directly find Du Niang for the material ingredients, and I will list them here without much space. The density of aluminum alloy is 2.63～2.85g/cm, it has higher strength (σb is 110～270MPa), the specific strength is close to that of high alloy steel, the specific stiffness is higher than that of steel, it has good casting performance and plastic processing performance, and good electrical conductivity. , Thermal conductivity, good corrosion resistance, and solderability.

The fluidity of die-cast aluminum alloy is relatively good, and the melting point is 660°C.

Aluminum alloy has the richest form of process application in the product structure design. Common processing processes include: die casting, extrusion molding, machining, stamping, and forging. A large number of aluminum alloy profiles are used for building doors and windows, and aluminum profiles are often used to build frames for machinery and equipment. There is no lack of aluminum alloys for the shells of electronic products and fast-moving consumer goods. These products have higher appearance requirements. The more common processes are extrusion, machining, stamping, etc.

Die-cast aluminum is rarely used for the shell of fast-moving consumer goods because the die-cast aluminum alloy contains a higher composition of Si, so when doing anodizing (anodizing), it directly reacts with the chemical solution, and the surface effect after oxidation is relatively poor. Aluminum castings are often used for internal structural parts and parts that do not require a high appearance. Motorcycle engine shells require complex structures, are lightweight, and have sufficient strength. Most rotating aluminum alloys die castings are used as blanks.

Aluminum grades:

1××× series is: pure aluminum (aluminum content is not less than 99.00%), the last two digits of this series of grades are expressed as the percentage of the lowest aluminum content. The second letter of the grade indicates the modification of the original pure aluminum.

The last two digits of 2×××～8××× series grades have no special meaning and are only used to distinguish: different aluminum alloys in the same group. The second letter of the grade indicates the modification of the original pure aluminum.

2××× series: aluminum alloy with copper as the main alloying element. 2011 free-cutting alloy, good machinability, and high strength. 2018 2218 Alloy for forging, with good forge ability and high-temperature strength.

3××× series: aluminum alloy with manganese as the main alloying element. 3105 3105 building materials, colored aluminum plates, bottle caps.

4××× series: aluminum alloy with silicon as the main alloying element. 4032 has good heat resistance, abrasion resistance, and low thermal expansion coefficient. Piston, cylinder head.

The 5××× series is aluminum alloy with magnesium as the main alloying element. 5052 is the most representative alloy of medium strength, general sheet metal, ships, vehicles, construction, bottle caps, honeycomb panels.

The 6××× series are aluminum alloys with magnesium as the main alloying element and the Mg2Si phase as the strengthening phase. 6063 is a representative extrusion alloy with lower strength than 6061 and good extrudability. It can be used as a profile with complex cross-sections and has good corrosion resistance and surface treatment. Construction, highway guardrails, high fences, vehicles, furniture, Home appliances, decorations.

7××× series: aluminum alloy with zinc as the main alloying element. 7075 aluminum alloy has one of the highest strength alloys, but the corrosion resistance is not good, and the covering skin of 7072 can improve its corrosion resistance, but the cost is increased. Aircraft, ski poles.

8××× series: aluminum alloy with other elements as main alloying elements

9××× series: spare alloy group

Aluminum alloys with a tensile strength greater than 480MPa are called high-strength aluminum alloys, mainly based on Al-Cu-Mg and Al-Zn-Mg-Cu alloys, namely 2XXX (hard aluminum alloy) and 7XXX (super hard aluminum) Alloys) series alloys. The static strength of the former is slightly lower than the latter, but the use temperature is higher than the latter. Due to the differences in alloy chemical composition, smelting and solidification methods, processing techniques, and heat treatment systems, the properties of alloys vary greatly.

Commonly used aluminum alloy performance table

Zinc alloy

Zinc alloy has a low melting point, good fluidity, and easy welding. According to the manufacturing process, it can be divided into cast zinc alloy and wrought zinc alloy. Cast zinc alloy has good fluidity and corrosion resistance and is suitable for die-casting instruments, auto parts shells, etc. Wrought zinc alloy has good plasticity and ductility, and is mainly used for battery shells, printed boards, roof panels, and daily hardware. The output of cast alloys is much greater than that of wrought alloys, and wrought alloys are rarely used for structural parts of fast-moving consumer goods. Therefore, the following is only for 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-casting.

Zinc alloy has a high specific gravity, which is the largest among the four alloys mentioned in this article. It also has the best fluidity and good casting performance. It can die-cast precision parts with complex shapes and thin walls, and the surface of the castings is smooth. Among the products I designed, the thinnest wall thickness of zinc alloy dies castings is only 0.4mm.

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°C) working environments. Zinc alloys have better mechanical properties at room temperature. However, the tensile strength at high temperature and the impact performance at low temperature is significantly reduced. Zinc alloy has poor corrosion resistance. When the impurity elements of lead, cadmium, and tin in the alloy composition exceed the standard, the casting will be aging and deformed. Zinc alloy die-castings have an aging effect and have an aging phenomenon, that is, the strength will naturally decrease after a long time and become brittle. This is why many people complain that when replacing the zinc alloy faucet, brittle fracture often occurs, causing the threaded part of the faucet to remain in the water pipe and cannot be removed. Therefore, Fanggong still recommends that you try to choose copper faucets instead of zinc alloy faucets when decorating.

At present, there are two major types of standard series used as castings in the world, one is ZAMAK alloy, and the other is ZA series alloy. The ZAMAK alloys used are ZAMAK 2, ZAMAK 3, ZAMAK5, and ZAMAK 7. (For the sake of simplicity, the above alloys are collectively referred to as No. 2, No. 3, No. 5, and No. 7 alloys). The ZA series include ZA-8, ZA-12, ZA-27, and ZA-35. ZA-8 is mainly used for hot chamber die casting, 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 casting. The development of ZAMAK alloys precedes the ZA series alloys and is mainly used for pressure casting. The most widely used is the No. 3 zinc alloy.

ZAMAK 2: Used for mechanical parts that have special requirements for mechanical properties, high hardness requirements, good wear resistance, and general dimensional accuracy requirements.

ZAMAK 3: Good fluidity and mechanical properties. Used in castings that do not require high mechanical strength, such as toys, lamps, decorations, and some electrical devices.

ZAMAK 5: Good fluidity and good mechanical properties. Used in castings that have certain requirements for mechanical strength, such as auto parts, electromechanical parts, mechanical parts, and electrical components.

ZA8: Good impact strength and dimensional stability, but poor fluidity. It is applied to die-casting workpieces with small size, high precision, and mechanical strength, such as electrical devices.

Superalloy: 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.

magnesium alloy

Magnesium alloys are alloys based on magnesium and added with other elements. The main alloying elements are aluminum, zinc, manganese, cerium, thorium, and a small amount of zirconium or cadmium. Currently, the most widely used is magnesium-aluminum alloy, followed by magnesium manganese alloy and magnesium zinc alloy. Magnesium alloys can be widely used in automobiles, electronics, textiles, construction, and military fields due to their excellent casting, extrusion, cutting, and bending properties.

The melting point of magnesium alloy is 650℃, which is lower than that of aluminum alloy and has good die-casting performance. The tensile strength of magnesium alloy castings is equivalent to that of aluminum alloy castings, generally up to 250 MPa, up to more than 600 MPa.

Magnesium alloy has a low density (about 1.8g/cm3) and high strength. Magnesium alloy is the lightest metal structural material, with a specific gravity of only 1.8, which is 2/3 of aluminum and 1/4 of iron, and its specific strength is as high as 133, which makes magnesium alloys useful as high-strength materials. The specific strength of high-strength magnesium alloys is even comparable to that of titanium.

Magnesium alloy has a large elastic modulus and good shock absorption. In the elastic range, when magnesium alloy is subjected to impact load, the energy absorbed is half that of aluminum alloy parts, so magnesium alloy has good shock resistance and noise reduction performance.

Magnesium alloy has good die-casting performance, and the minimum wall thickness of die-casting parts can reach 0.5mm, which is suitable for manufacturing all kinds of die-casting parts for automobiles. Magnesium alloy parts have high stability, and die-casting parts have high castability processing dimensional accuracy, and high-precision machining can be carried out.

Magnesium alloys have absolute advantages in heat dissipation relative to alloys. For heat sinks of magnesium alloy and aluminum alloy materials of the same volume and shape, the heat (temperature) produced by a certain heat source is easier to transfer from the root of the heat sink than aluminum alloy. The speed to the top makes it easier for the top to reach high temperatures.

However, the coefficient of linear expansion of magnesium alloy is very large, reaching 25～26 μm/m℃, while that of aluminum alloy is 23 μm/m℃, brass is about 20 μm/m℃, structural steel is 12 μm/m℃, and cast iron is about 10 μm/m. m℃, rock (granite, marble, etc.) is only 5-9 μm/m℃, and glass is 5-11 μm/m℃. When applied to a heat source, the influence of temperature on the size of the structure must be considered.

Magnesium alloy application examples: Generally, high-end and professional digital SLR cameras use magnesium alloy as the frame to make it sturdy and durable, with a good feel; shells for mobile phones and laptops; shells for computers and projectors that generate high temperatures inside Magnesium alloy is used for heat dissipation components; automotive steering wheels, steering brackets, brake brackets, seat frames, mirror brackets, distribution brackets and other structural parts that require lightweight and high strength.

According to the forming method, it is divided into two types: wrought magnesium alloy and cast magnesium alloy.

Magnesium alloy grades are expressed in the form of English letters + numbers + English letters. The first English letter is the code of the most important alloy composition element (the element code is specified in the following table), and the following number represents the average value of the upper and lower limit values of the most important alloy composition element. The English letter at the end is the identification code, which is used to identify different alloys with different specific constituent elements or slightly different element contents.

Commonly used grades of magnesium alloys are AZ31B, AZ31S, AZ31T, AZ40M, AZ41M, AZ61A, AZ61M, AZ61S, AZ62M, AZ63B, AZ80A, AZ80M, AZ80S, AZ91D, AM60B, AM50A, M1C, M2M, M2S, ZK61M, ZK61S, ME20M, ME20M, LZ61, LZ121, LA141, LA191, LAZ933, LA81, LA91, LAZ931, MA18, MA21, MA14, etc.

Titanium alloy

Titanium alloy refers to a variety of alloy metals made of titanium and other metals, with high strength, good corrosion resistance, and high heat resistance. Titanium alloys are widely used in the production of aircraft engine compressor parts, skeletons, skins, fasteners, and landing gears. Titanium alloys are also used in the structural parts of rockets, missiles, and high-speed aircraft.

Titanium is an allotrope with a melting point of 1668°C. When it is lower than 882°C, it has a close-packed hexagonal lattice structure, called α titanium; it has a body-centered cubic lattice structure above 882°C, called β titanium. Using the different characteristics of the above two structures of titanium, add appropriate alloying elements to obtain titanium alloys with different structures. At room temperature, titanium alloys have three matrix structures, and titanium alloys are divided into the following three categories: α alloys, (α+β) alloys, and β alloys. my country is represented by TA, TC, and TB respectively.

The density of titanium alloy is generally about 4.51g/cm3, which is only 60% of steel. Some high-strength titanium alloys exceed the rigid strength of many alloy structures, so the specific strength (strength/density) of titanium alloys is much greater than other metal structural materials, Can produce parts with high unit strength, good rigidity, and lightweight.

Mechanical properties of some titanium and titanium alloys

Titanium alloy products

Titanium is non-toxic, light in weight, high in strength, and has excellent biocompatibility. It is a very ideal medical metal material and can be used as an implant for implantation in the human body. In the United States, five beta titanium alloys have been recommended to the medical field, namely TMZFTM (TI-12Mo-^Zr-2Fe), Ti-13Nb-13Zr, Ti metal 21SRx (TI-15Mo-2.5Nb-0.2Si), Tiadyne 1610 (Ti-16Nb-9.5Hf), and Ti-15Mo are suitable for implanting into the human body as implants, such as artificial bones, vascular stents, etc.

The biocompatibility of TiNi alloy is very good, and there are many medical examples using its shape memory effect and superelasticity. Such as thrombus filters, spinal orthopedic rods, orthopedic wires, vascular stents, bone plates, intramedullary needles, artificial joints, contraceptives, cardiac repair components, artificial kidney micro-pumps, etc.

Titanium alloy products can be obtained by die casting and machining methods. The melting temperature of titanium alloy is very high, and the requirements for mold steel are also high. There are many machining methods for titanium alloys, mainly including: turning, milling, boring, drilling, grinding, tapping, sawing, EDM, and so on.

The machining performance of titanium alloy is also poor. The cutting force during the cutting of titanium alloy is only slightly higher than that of steel of the same hardness, but most titanium alloys have very low thermal conductivity, only 1/7 of steel and 1/16 of aluminum, so the heat generated by cutting will not quickly dissipate, Which gathers in the cutting area, causes the cutting edge of the tool to wear rapidly, collapse and generate built-up edge。