General trend of the last years is significant increase in consumption of special steels and alloys which cutting and shaping involve considerable difficulties. Nowadays requirements for HS-steel properties become stricter.
The main property of HS-steel is heat-resistance, in other words, capability of steel to retain high hardness, toughness and wear resistance at elevated temperatures.
It is known that tools warm up during cutting and the higher speed of cutting and hardness of processed material, the higher temperature of tools. It is very important to have tools that do not lose cutting properties at high speed of cutting. Tools of HS-steels can work at 550-600°C.
HS-steels have been known long time. Chemical composition improvements resulted in new steel grades that are used in different applications.
Since HS-steels contain large amount of alloying elements they can be easily quenched in the air. These steels are sensitive to cracks as significant stresses occur in them even with slight quenching. It is difficult to obtain required hardness for these steels as they can be easily oxidized and decarburized by heat treatment.
Heat treatment of tools is an even more difficult process. To prevent oxidizing and decarburizing of steel at the tool quenching temperature it should be heated in a chemical bath.
Steel heat resistance is characterized by hardness in annealed state that should be 58 HRC minimum.