Carbon steels, free-cutting steels

About the material

Carbon steels and free-cutting steels are among the most important materials in the metalworking industry – especially where high strength, good workability or elastic properties are required. They are used, for example, in precision mechanics, watchmaking, medical technology and instrument making.

Carbon steels

Carbon steels are predominantly made of iron with a variable carbon content (typically 0.25-1.00%), which strongly influences the mechanical properties such as tensile strength, hardness and modulus of elasticity. The higher the carbon content, the harder and more brittle the material.

Some common materials in the Jacques Allemann portfolio:

• 100Cr6 (1.3505 / 100C6)
  High-alloy roller bearing steel with approx. 1.0% C and 1.5% Cr. Ideal for applications with high wear stress and excellent hardenability.
  Use: roller bearings, precision bearings, valve components
• C72D (1.0617 / 1070)
  Non-alloy spring steel with high carbon content (~0.70%), suitable for heat-treated components with high elasticity.
  Use: springs, clips, small mechanical parts
• piano wire (1.1211)
  Especially for high-strength wires such as for springs or musical instruments. Often patented cold-drawn to achieve maximum strength.
  Use: spring wires, piano strings, technical spirals

Free-cutting steels

Free-cutting steels are specially optimised for working – particularly turning and milling. Additives such as lead (Pb), sulphur (S) or phosphorus (P) produce short swarf and better swarf removal. However, these steels are not suitable for heat treatment or welding processes.

Typical alloys:

• 11SMnPb37 (1.0737 / S300Pb)
  Classic lead free-cutting steel with very good machinability. Contains approx. 0.35% C, 1.5% Mn and added Pb.
  Use: series parts on machines, screws, precision turned parts
• Laboratory Pb (1.0759 / 70SPb20)
  Lead-alloyed free-cutting steel with a particularly fine microstructure, suitable for small components with tight tolerances.
  Use: medical technology, analytical instruments
• LAW100PB / Sandvik 20AP (1.1268 + Pb)
  Tool steel with high carbon content (~1%) and added lead for ideal workability.
  Use: small parts with increased hardness, measuring instruments

Specialities

4C27A / X22CrMoNiS13-1 (F899)
Martensitic stainless steel with added sulphur for better workability. Common standard for surgical instruments.
Use: medical cutting tools, dental technology