High Speed Steel (HSS) is a kind of China cnc machining some other elements: carbon, tungsten, molybdenum, chromium, vanadium, and/or cobalt. After heat treatments, it will have high hardness even at high temperatures. When the cutting temperature exceeds 600°C, the hardness of HSS will not decrease apparently. The cutting speed of cutting tools made of HSS can exceed 60 meters per minute, thus High Speed Steel gets its name. HSS can be classified as ordinary HSS and high performance HSS by its chemical composition, and can also be classified as melting HSS and powder metallurgy HSS by its manufacturing process.
1. Ordinary HSS
Ordinary HSS can meet general needs. Two commonly sighted types of it are tungsten series HSS and tungsten-molybdenum series HSS.
a. Tungsten series HSS
Its typical grade is W18Cr4V. After heat treatment, its hardness can reach 63 – 66 HRC, and bending strength reaches 3500 MPa. Its grindability is good.
b. Tungsten-molybdenum series HSS
Its typical grade is W6Mo5Cr4V2, which is now replacing the tungsten series HSS. Its carbide is small and evenly distributed. It has high abradability, and is at low cost. Its hardness after heat treatment is same as W18Cr4V, but its bending strength can reach 4700 MPa. Its toughness and thermoplasticity are higher than W18Cr4V by 50%. It is usually used to manufacture a variety of tools, such as drill bits, taps, and reamers. It can meet the general processing of engineering materials. Its decarbonization sensitivity is a little bit high.
Another Grade is W9Mo3Cr4V, which is a new variety developed in China. Its toughness and thermoplasticity are a little bit higher than W6Mo5Cr4V2. Its hardness is 63 – 64 HRC. It is easy for rolling and forging. Its decarbonization sensitivity is low. Its cost is also lower.
2. High performance HSS
High performance HSS has a better hardness. This is a new developed variety by changing the chemical composition of HSS and improving its performance. Its hardness can stay at more than 60 HRC when the cutting temperature reaches 650°C. Its durability is 1.5 – 3 times of that of Ordinary HSS. It is applicable to manufacture the cutting tools for processing high temperature alloys, stainless steel, titanium alloys, high-strength steel, and other hard materials. There are 4 main varieties, namely high-carbon series HSS (its typical grade is 9w18Cr4V), high-vanadium series HSS (its typical grades are W12Cr4V4Mo and W6Mo5Cr4V3), cobalt series HSS (its typical grade is W2Mo9Cr4VCo8), and aluminum HSS (its typical grades are W6Mo5Cr4V2Al and W6Mo5Cr4V5SiNbAl).