It means diversity of steel alloy and carbon.

Toughness, resistance to abrasion , ability to hold a cutting edge, and resistance to deformation at elevated temperatures (red-hardness) make carbon and steel alloy agreeing to be a tool steel.

To produce high quality of tool steel we work under controlled state keeping carbon content between 0.7% and 1.4%, and low content of manganese depreciating the chance of cracking during water quenching . It's momentous to make a suitable heat treating to adequate performance. For oil quenching many suppliers intended to provide tooling blanks.

Necessity of a keen cutting edge in stamping dies , or withstand impact loading service conditions encountered with hand tools as axes , pickaxes , and quarrying implements, make a different grades of applications that depend on it.

The higher carbon grades are used for applications as stamping dies, metal cutting tools, etc. the edge temperature under expected use is an important determinant of both composition and required heat treatment.

A typical composition is: