Chemical composition:
Main component: High-density tungsten alloys are based on tungsten, and the tungsten content is usually 85%-99%. The tungsten content of different alloy series is slightly different. For example, tungsten is the main component in tungsten-nickel-iron alloys, while nickel, iron, etc. are added as additives to adjust the performance; the tungsten content in tungsten-nickel-copper alloys is also high, and it also contains a certain proportion of nickel and copper.
Alloy elements: In addition to tungsten, a small amount of Ni, Fe, Cu, Co, Mo, Cr and other elements are added. The addition ratio of these elements needs to be strictly controlled to ensure that the alloy has the required properties. For example, the addition of Ni and Fe can improve the toughness and ductility of the alloy, and the addition of Cu can improve the processing performance of the alloy.
Physical properties:
Density: The density of high-density tungsten alloys is one of its important characteristics, generally 16.5-19.0g/cm³. The density of different grades of high-density tungsten alloys will be different. For example, the density of 90WNiFe is usually 17.1±0.15g/cm³, and the density of 97WNiFe is around 18.50±0.15g/cm³.
Hardness: The hardness requirements of high-density tungsten alloys are different according to different application requirements. Usually the hardness is above HRC20, and the hardness of tungsten alloys with special treatment or specific grades can be higher.
Thermal expansion coefficient: The thermal expansion coefficient is low, generally 4-6×10⁻⁶/℃, which makes the tungsten alloy have less dimensional changes when the temperature changes, and is suitable for occasions with high dimensional stability requirements.
Thermal conductivity: The thermal conductivity is relatively large, about 5 times that of mold steel. The good thermal conductivity makes tungsten alloys have advantages in heat dissipation and other aspects.
Mechanical properties:
Tensile strength: The tensile strength is relatively high, usually 700-1000MPa. After heat treatment and deformation processing, the strength can be further increased to 1300-1500MPa.
Ductility: It has a certain degree of ductility. For example, the sintered elongation of tungsten-nickel-iron alloy can reach 10%-15%. After vacuum or atmosphere dehydrogenation treatment, the elongation can be increased to 20%-30%.
Dimensions and deviations:
Plate: For tungsten-based high-density alloy plates, there are corresponding dimensional requirements and allowable deviations for thickness, width and length. For example, when the thickness of the sintered product is 2.0-50.0mm, the allowable deviation of the thickness varies according to the grade, and the allowable deviation of the width and length also has corresponding regulations; the allowable deviation of the thickness, width and length of the rolled product also has clear standards.
Bars and other shapes: For high-density tungsten alloy products in other shapes such as bars and cylinders, their diameter, length and other dimensions also have corresponding standards and allowable deviation ranges.
Appearance quality:
Surface defects: Whether it is a sintered product or a rolled product, the surface should be free of defects as much as possible. For example, no missing corners, visible delamination, holes, or inclusions are allowed; the surface of sintered products should not have local over-melting, bulging, or cracks, and should not have edge loss, corner loss, or pits that affect use; the surface of rolled products should be clean, and no cracks, peeling, folding, cracking, metal or non-metallic indentation, etc. are allowed. Minor scratches, roller marks, pits, and pitting are allowed.
Edge quality: For rolled products, the edges should be cut neatly without cracks, and minor shearing defects are allowed.
Tungsten-based heavy alloys can generally be divided into the following categories:
Tungsten-nickel-iron alloy (W-Ni-Fe):
This is one of the most common types of tungsten-based heavy alloys. It is mainly composed of tungsten, usually with a tungsten content of about 85% - 97%. Nickel and iron are added as binder elements, with nickel content of about 3% - 7% and iron content of 1% - 3%.
This alloy has good comprehensive properties, including high density, good strength and toughness, and certain ductility. Its density generally ranges from 16.5 - 18.5 g/cm³, and is suitable for a variety of fields, such as counterweight components in the aerospace field, gyro rotors in inertial navigation systems, etc. It is also widely used in industry for die-casting molds, armor-piercing projectile cores and other components, because its high density can provide good inertia and penetration performance, while good toughness and strength ensure reliability during use.
Tungsten-nickel-copper alloy (W-Ni-Cu):
Tungsten is also used as the main high-density element, and the tungsten content is also at a high proportion, generally 85% - 95%, the nickel content is 2% - 6%, and the copper content is 3% - 9%.
This alloy is characterized by non-magneticity and good machinability and weldability. Its density is slightly lower than that of tungsten-nickel-iron alloy, about 16.0 - 18.0 g/cm³. Due to its non-magnetic characteristics, it is widely used in the electronic and electrical fields. For example, in electronic packaging materials, it can avoid magnetic interference with electronic components; in some mechanical parts that require high-precision processing and assembly, good processing and welding performance also gives it an advantage. At the same time, its higher density also meets some application scenarios that require weight.
Tungsten-Molybdenum-Nickel-Iron Alloy (W-Mo-Ni-Fe):
In addition to tungsten, molybdenum is also added. Usually, the tungsten content is 70% - 85%, the molybdenum content is 5% - 15%, and the nickel and iron content is similar to that of tungsten-nickel-iron alloy, with nickel at 3% - 6% and iron at 1% - 3%.
The addition of molybdenum improves some properties of the alloy, such as reducing the thermal expansion coefficient, improving the high-temperature strength and hardness of the alloy, and making it have better thermal stability. This alloy is often used for parts in high-temperature environments, such as turbine blades of aircraft engines, heating element support parts of high-temperature furnaces, etc. It is also used in the field of die-casting molds. It can withstand high temperature and high pressure working conditions and improve the service life and production efficiency of the mold.
Tungsten-Cobalt Alloy (W-Co):
Mainly composed of tungsten and cobalt, the tungsten content is relatively high, generally 80% - 95%, and the cobalt content is 5% - 20%.
This alloy has high hardness, high wear resistance and good corrosion resistance, and its hardness can reach HRA85 - 92. It is widely used in the field of tool manufacturing, for example, it is used to manufacture carbide tools, such as turning tools, milling cutters, drill bits, etc., which can maintain a sharp edge during the cutting process, improve processing accuracy and efficiency, and is also suitable for some mechanical parts with high requirements for wear resistance and corrosion resistance, such as key components in oil extraction equipment, wear-resistant and corrosion-resistant parts in chemical machinery, etc.
Tungsten-titanium-alloy.html>titanium alloy (W-Ti):
It is composed of tungsten and titanium, with a tungsten content of 70% - 90% and a titanium content of 10% - 30%.
The addition of titanium gives the alloy higher strength and certain toughness, while improving the alloy's oxidation resistance. The alloy is used in some structural parts in the aerospace field, such as in some high-temperature resistant structural parts of aircraft engines, using its high strength and oxidation resistance to meet harsh working conditions; in some high-end sports equipment, such as golf club heads, tennis racket frames, etc., tungsten-titanium alloys are also used to achieve lightweight and high-strength requirements, improving the performance and service life of the equipment.
Tungsten-rhenium alloy (W-Re):
Mainly contains tungsten and rhenium elements, with tungsten content of 90% - 99% and rhenium content of 1% - 10%.
The addition of rhenium significantly improves the high temperature strength, plasticity and recrystallization temperature of the alloy, making it have good high temperature performance and creep resistance. It is often used to manufacture high temperature components of aerospace engines, such as combustion chambers, turbine guide blades, etc. These components work in harsh environments of high temperature, high pressure and high stress. Tungsten-rhenium alloy can ensure the reliability and long life of the components; tungsten-rhenium alloy is also used in thermocouple wires of some high temperature measuring instruments, using its stable thermoelectric properties to achieve accurate temperature measurement.
Tungsten-tantalum alloy (W-Ta):
Composed of tungsten and tantalum, tungsten content is 80% - 95%, and tantalum content is 5% - 20%.
The addition of tantalum can improve the strength, hardness and corrosion resistance of the alloy, especially in some strong corrosive media environments, tungsten-tantalum alloy shows good stability. It is used in the fields of chemical industry, electronics, etc., such as corrosion-resistant pipes, valves and other components in chemical equipment, and some special electrode materials in the electronics industry, using its corrosion resistance and special electrical properties to meet the needs of production and scientific research.
Tungsten-niobium alloy (W-Nb):
It is mainly a combination of tungsten and niobium, with a tungsten content of 85% - 95% and a niobium content of 5% - 15%.
The addition of niobium can improve the processing performance and toughness of the alloy, and at the same time improve the high-temperature performance of the alloy to a certain extent. This alloy is used in some high-temperature structural components and electronic fields, such as in the support components of some high-temperature furnaces, using its good high-temperature performance and processing performance to meet the requirements of the equipment; in the manufacture of electron tubes, tungsten-niobium alloy is also used as an electrode material, etc., to give full play to its unique electrical and physical performance advantages.
