High Speed Steel is a sort of steel containing some other elements : carbon, tungsten, molybdenum, chromium, vanadium, and / or cobalt.
After heat treatments, it’ll have high toughness even at elevated temperatures. When the cutting temperature surpasses 600C, the toughness of HSS won’t lessen seemingly. The cutting speed of cutting tools made from HSS can surpass sixty meters per minute, so High Speed Steel gets its name. HSS can be categorized as normal HSS and high-performance HSS by its chemical composition, and may also be cataloged as softening HSS and powder metallurgy HSS by its producing process.
* Standard HSS Standard HSS can meet general wants.
2 frequently sighted sorts of it are tungsten series HSS and tungsten-molybdenum series HSS.
A. Tungsten series HSS Its standard grade is W18Cr4V. After heat treatment, its toughness can reach 63 – sixty six HRC, and bending strength reaches 3500 MPa. Its grindability is good.
B. Tungsten-molybdenum series HSS Its classic grade is W6Mo5Cr4V2, which is now replacing the tungsten series HSS. Its carbide is little and uniformly distributed. It has high abradability, and is at minimal cost. Its toughness after heat treatment is same as W18Cr4V, but its bending strength can reach 4700 MPa.
Its hardness and thermoplasticity seem higher than W18Cr4V by fifty percent. It is mostly used to make a range of tools , for example drill bits, taps, and reamers. It can meet the general processing of engineering materials. Its decarbonization sensitiveness is a touch high.
Another Grade is W9Mo3Cr4V, which is a new variety developed in China. Its hardness and thermoplasticity are a tiny bit higher than
* Its toughness is 63 – 64 HRC. It is simple for rolling and forging. Its decarbonization sensitiveness is low. Its cost is also lower.
* High-performance HSS
High-performance HSS has a better toughness. This is a new developed variety by changing the chemical composition of HSS and improving its performance. Its toughness can stay at more than sixty HRC when the cutting temperature reaches 650C. Its sturdiness is 1.5 – three times of that of Standard HSS. It is relevant to make the cutting tools for processing high temperature alloys, stainless-steel, titanium alloys, high-strength steel, and other hard materials.
There are four main variations, specifically high-carbon series HSS ( its standard grade is 9w18Cr4V ), high-vanadium series HSS ( its characteristic grades are W12Cr4V4Mo and W6Mo5Cr4V3 ), cobalt series HSS ( its characteristic grade is W2Mo9Cr4VCo8 ), and aluminium HSS ( its classic grades are W6Mo5Cr4V2Al and W6Mo5Cr4V5SiNbAl ).
* Powder metallurgy
HSS Powder metallurgy HSS effectively worked out liquefying HSS’s issue of the gigantic carbide segregation in rod casting. Grade APM T15 powder metallurgy HSS’s hardness is 2.5 times of that of liquefying HSS that has the same chemical composition. Its toughness in high temperature is also improved by 0.5 – one HRC. Its grindability is good. Due to its high level of isotropic mechanical property, powder metallurgy HSS’s toughening deformation is little, and it has bigger surface that has uniform distribution of carbide particles. These carbide particles aren’t simply to fall off from the sharp edge of tools. By utilizing powder metallurgy HSS, the abradability of tiny size tools can be improved by 1.5 – two times, and twenty – 30 percent for enormous size tools. The production process of powder metallurgy HSS is more involved than that of liquefying HSS, and its costs appear higher.
* The market position and trends of HSS
HSS has played a very important part in the development of modern industry. It may be said that no HSS, there would be no modern metal processing industry.
Though the applications of other materials like hard amalgamate have risen, HSS still has a dominant position in producing the cutting tools which have complicated shapes or are tricky to be ground , for example broaches, shaving cutters, pinion cutters, and so on. Particularly, when high hardness is needed, HSS is the required choice. The key application fields of HSS are machinery and tools producing industries. HSS should conform to the development of these industries. In the machinery processing, many CNC machine tools , for example processing centres, turning centres, etc, have been employed. The metal cutting speed becomes quicker and quicker. This specifies that cutting tools must have high speed performance, that is, good toughness at raised temperatures, good abradability and good hardness. Many makers have developed many HSS materials which can meet these wants.