Current status of tungsten steel
Sintering process The sintering molding of tungsten steel is to press the powder into the blank, then heat it into the sintering furnace to a certain temperature (sintering temperature), and maintain a certain time (holding time), and then cool down, so as to obtain the required properties of tungsten steel material. Four basic stages of sintering of tungsten steels: 1. the stage of removing the forming agent and pre-sintering, the following changes occurred in the sintered body at this stage: In the early stage of sintering with the increase of temperature, the forming agent gradually decomposes or vaporizes to exclude the sintered body. At the same time, the forming agent more or less carbonizes the sintered body, and the amount of carbonation will change with the variety, quantity and sintering process of the forming agent. the oxide on the powder surface is reduced. at the sintering temperature, hydrogen can reduce the oxides of cobalt and tungsten. if the molding agent is removed in vacuum and sintering, the carbon-oxygen reaction is not strong. the contact stress between the powder particles was gradually eliminated, and the bonded metal powder began to produce recovery and recrystallization, and the surface diffusion began to occur, and the strength of the compression block was improved. 2. solid phase sintering stage (800℃—— eutectic temperature) At the temperature before the liquid phase appeared, in addition to continuing the process that occurred in the previous stage, the solid phase reaction and diffusion intensified, the plastic flow enhanced, and the sintered body appeared obvious shrinkage. 3. liquid sintering stage (eutectic temperature —— sintering temperature) When the sintered body appears liquid phase, the shrinkage is completed quickly, and then the crystallization transition is produced to form the basic structure and structure of the alloy. 4. cooling stage (sintering temperature —— room temperature) at this stage, the microstructure and phase composition of tungsten steel have some changes with different cooling conditions. this feature can be used to heat the tungsten steel to improve its physical and mechanical properties. Application Introduction Tungsten steel belongs to cemented carbide, also known as tungsten titanium alloy. The hardness can reach 89~95 HRA, Because of this, tungsten steel products (common with tungsten steel watches), with not easy to be worn, hard not afraid of annealing, but brittle characteristics. The main components of cemented carbide are tungsten carbide and cobalt, which account for 99% of all components and 1% are other metals, so it is also called tungsten steel. Often used in high precision machining, high precision tool material, lathe, impact drill bit, glass knife head, ceramic tile cutting knife above, hard not afraid of annealing, but brittle. Of rare metals. tungsten steel (cemented carbide) 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, which remain basically unchanged even at 500℃ temperature, and still have a high hardness at 1000℃. cemented carbide is widely used as material, such as turning tool, milling cutter, planer, drill bit, boring tool, etc. it is used to cut cast iron, non-ferrous metal, plastic, chemical fiber, graphite, glass, stone and ordinary steel. it can also be used to cut heat-resistant steel, stainless steel, high manganese steel, tool steel and other hard-working materials. The cutting speed of new cemented carbide is hundreds of times that of carbon steel. Tungsten steel (cemented carbide) can also be used to make rock drilling tools, mining tools, drilling tools, measuring tools, wear-resistant parts, metal abrasives, cylinder linings, precision bearings, nozzles, etc.