1040 – 06 – Consider the Work Hardening Effect

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Steel’s hardness and strength is usually the result of two things: carbon content inside of the material and work hardening. The more carbon in the steel, the harder steel will be. It is important to note, though, that many steels with low level of carbon can be hardened through cold working. When metal is shaped and deformed by cold working, its surface begins to harden.

Steel that has been case-hardened is usually much easier to machine. The metal itself forms a hard exterior surface with a softer material underneath. If the material is used in a cutting operation with a higher feed rate, the cutting tool will slice through this hardened exterior and remove the much softer interior metal. This makes it easier to remove material and improve its machinability.