Carbide segregation is easy to occur in smelting high speed steel, hard and brittle carbide is not evenly distributed in high speed steel, and the coarse grain size (8 ~ 20μm) will adversely affect the wear resistance, toughness and cutting performance of high speed steel tools.
Powder metallurgy high speed steel is a new kind of cutting tool material development in the 1970 s, it is a high frequency induction furnace smelting of steel liquid steel with high pressure argon gas or pure nitrogen atomization by tiny uniform crystal structure (high speed steel powder), then the powder under the high temperature and high pressure tool blank, also can be made into billet first, then through forging, rolling into a tool.
Powder metallurgy high speed steel is a high performance high speed steel produced by powder metallurgy technology or a tool material directly formed. The composition can be close to that of ordinary high speed steel. The process includes atomizing pulverizing, vacuum deoxidizing of powder, billet making and firing. Atomizing powder is to rely on high-speed inert gas or high pressure water impact molten steel flow, then atomized into small droplets and solidified into powder. The powder is deoxidized and sintered into materials or cutting tools at high temperature. The structure is characterized by the absence of chemical segregation, fine carbide particles and uniform distribution, which significantly improves toughness, thus allowing an increase in the volume fraction of carbide and improved wear resistance. Heat treatment temperature range is wide, can be heated at very high temperature without overheating. It is used to produce high speed steel with high vanadium and niobium content which is difficult to be made by conventional methods. The high performance special high speed steel between high speed steel and hard alloy can also be obtained by adding wear-resistant super hard micro powder into the powder.
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