Steels for Twist drill bits quoted from Machinery's Handbook 27th Edition

Twist drill steels need good toughness, abrasion resistance, and

ability to resist softening due to heat generated by cutting. The amount of heat generated

indicates the type of steel that should be used.

Carbon Tool Steel may be used where little heat is generated during drilling.

High-Speed Steel is preferred because of its combination of red hardness and wear resistance,

which permit higher operating speeds and increased productivity. Optimum properties

can be obtained by selection of alloy analysis and heat treatment.

Cobalt High-Speed Steel alloys have higher red hardness than standard high-speed

steels, permitting drilling of materials such as heat-resistant alloys and materials with

hardness greater than Rockwell 38 C. These high-speed drills can withstand cutting speeds

beyond the range of conventional high-speed-steel drills and have superior resistance to

abrasion but are not equal to tungsten-carbide tipped tools.

Widtop is a HSS drill bits manufacturer in China