Tungsten steel (hard alloy) has a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance and corrosion resistance, especially its high hardness and wear resistance, even at a temperature of 500 ℃ Basically remain unchanged, still very high hardness at 1000 ℃.
|Features||high hardness, wear resistance, strength and toughness, etc.||Product||round bar, tungsten steel sheet|
Tungsten steel, also known as cemented carbide, refers to a sintered composite material composed of at least one metal carbide. Tungsten carbide, cobalt carbide, niobium carbide, titanium carbide, and tantalum carbide are common components of tungsten steel. The grain size of the carbide component (or phase) is usually between 0.2-10 microns, and the carbide grains are bonded together using a metal binder. The binder usually refers to the metal cobalt (Co), but for some special applications, nickel (Ni), iron (Fe), or other metals and alloys can also be used. The composition combination of a pending carbide and binder phase is called “brand”.
The classification of tungsten steel is carried out according to ISO standards. This classification is based on the material type of the workpiece (such as P, M, K, N, S, H grades). The binder phase component mainly uses its strength and corrosion resistance.
The matrix of tungsten steel is composed of two parts: one part is the hardening phase; the other part is the bonding metal. The bonding metal is generally iron group metal, and cobalt and nickel are commonly used. So there are tungsten-cobalt alloys, tungsten-nickel alloys and tungsten-titanium-cobalt alloys.
Tungsten-containing steels, such as high-speed steel and certain hot-work die steels. Tungsten in the steel can significantly improve the hardness and heat resistance of the steel, but the toughness will drop sharply.
The main application of tungsten resources is also cemented carbide, that is, tungsten steel. Cemented carbide is called the teeth of modern industry, and tungsten steel products are widely used.
Current Situation In China
The main problems existing in China’s cemented carbide industry: First, the scale of enterprises is small and the industry concentration is not high. According to incomplete statistics, 199 cemented carbide companies have an average annual production capacity of 176 tons, an average annual output of only 86 tons, and only 4 companies with an annual output of more than 1,000 tons.
Second, the investment in science and technology is small, the lack of high-end technical talents, and the weak technological research and development capabilities. China’s cemented carbide industry’s investment in technology is less than 3% of sales revenue, the level of scientific and technological research and development is not high, and the original core technological achievements are few. The third is the low level of product quality, and the product structure needs to be adjusted. China’s cemented carbide production accounts for more than 40% of the world’s total output, but cemented carbide sales revenue is less than 20% of the world’s total, mainly due to high-performance ultra-fine alloys, high-precision and high-performance abrasive coated blades, super-hard tool materials, and complex Due to the low output of high value-added products such as large-scale products and precision cemented carbide CNC tools, insufficient deep-processing supporting facilities and incomplete varieties.
With the rapid expansion of China’s auto industry, the demand for cutting tools for auto parts processing continues to increase, and the demand for cemented carbide in the fields of China’s steel, transportation, and construction is also growing. In the strategic vision of foreign cemented carbide multinational companies, the Chinese market has quietly changed from a supporting role to a leading role.
The analysis pointed out that by the end of the “Twelfth Five-Year Plan”, China’s cemented carbide output reached 30,000 tons, sales revenue reached 30 billion yuan, and the output of deep-processed products accounted for more than 40% of the total cemented carbide. Compared with the “Eleventh Five-Year Plan”, exports will double and strive to exceed 1 billion U.S. dollars. Cemented carbide will develop in the direction of fine and deep processing and tool matching; develop in the direction of ultra-fine, ultra-coarse and coated composite structures; develop in the direction of circular economy, energy saving and environmental protection; develop in the direction of precision and miniaturization
Tungsten steel sintering molding is to press the powder into a blank, then heat it into a sintering furnace to a certain temperature (sintering temperature), keep it for a certain time (holding time), and then cool it down to obtain the tungsten steel material with the required performance.
The four basic stages of the tungsten steel sintering process:
- During the removal of forming agent and pre-sintering stage, the sintered body undergoes the following changes at this stage:
Removal of the forming agent, as the temperature rises in the initial stage of sintering, the forming agent gradually decomposes or vaporizes to remove the sintered body. At the same time, the forming agent more or less carbonizes the sintered body. The type, quantity, and sintering process vary.
The oxides on the powder surface are reduced. At the sintering temperature, hydrogen can reduce the oxides of cobalt and tungsten. If the forming agent is removed in vacuum and sintering, the carbon-oxygen reaction is not strong. The contact stress between the powder particles is gradually eliminated, the bonding metal powder begins to recover and recrystallize, surface diffusion begins to occur, and the strength of the compact increases.
- Solid phase sintering stage (800℃——eutectic temperature)
At the temperature before the appearance of the liquid phase, in addition to continuing the process that occurred in the previous stage, the solid phase reaction and diffusion intensify, the plastic flow is enhanced, and the sintered body exhibits obvious shrinkage.
- Liquid phase sintering stage (eutectic temperature-sintering temperature)
When the sintered body appears in the liquid phase, the shrinkage is quickly completed, and then crystalline transformation occurs, forming the basic structure and structure of the alloy.
- Cooling stage (sintering temperature-room temperature)
At this stage, the structure and phase composition of tungsten steel have some changes with different cooling conditions. This feature can be used to heat tungsten steel to improve its physical and mechanical properties.
Tungsten steel belongs to cemented carbide, also known as tungsten-titanium alloy. The hardness can reach 89~95HRA. Because of this, tungsten steel products (commonly tungsten steel watches) are not easy to be worn, hard and not afraid of annealing, but are brittle.
The main components of cemented carbide are tungsten carbide and cobalt, which account for 99% of all components, and 1% is other metals, so it is also called tungsten steel.
It is often used in high-precision machining, high-precision tool materials, lathes, impact drill bits, glass cutter bits, and tile cutters. It is hard and not afraid of annealing, but it is brittle. Belongs to rare metals.
Tungsten steel (hard alloy) has a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance and corrosion resistance, especially its high hardness and wear resistance, even at a temperature of 500 ℃ Basically remain unchanged, still very high hardness at 1000 ℃. Cemented carbide is widely used as materials, such as turning tools, milling cutters, planers, drills, boring cutters, etc., for cutting cast iron, non-ferrous metals, plastics, chemical fibers, graphite, glass, stone and ordinary steel. It can also be used for cutting resistant Hard-to-process materials such as hot steel, stainless steel, high manganese steel, tool steel, etc. The cutting speed of the new cemented carbide is hundreds of times that of carbon steel.
Tungsten steel (hard alloy) can also be used to make rock drilling tools, mining tools, drilling tools, measuring tools, wear-resistant parts, metal abrasive tools, cylinder linings, precision bearings, nozzles, etc.
Tungsten steel grade comparison: S1, S2, S3, S4, S5, S25, M1, M2, H3, H2, H1, G1 G2 G5 G6 G7 D30 D40 K05K10 K20 YG3X YG3 YG4C YG6 YG8 YG9 YG12 YL10.2 YL60 YG15 YG20 YG25 YG28YT5 YT14 YT15 P10 P20 M10 M20 M30 M40 V10 V20 V30 V40 Z01 Z10 Z20 Z30
Tungsten steel, cemented carbide molds, plates, top hammers, roll rings, cutting tools, and various tungsten carbide standard specifications have a large inventory, and the blanks are available from stock
Such as: sheet type (length * width * height)
6120 (2-15) 80110 (2-30)
70240 (10-55) 100100 (2-75)
105-105(2-60)100160(10-60) 100200* (10-60) 125125 (2-15)
150150 (2-60) 165220 (2-6)
200200 (2-60) 200300 (2-9)
Other strips: 1006(3-6) 1008(3-8) 10010(5-10) 10012(6-12) 150155…
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