Machinability as Influenced by the Composition, Microstructure, and Cold Extrusion of Steel

The relationship of machinability to the carbon, sulfur, phosphorus, nitrogen, and other alloy contents of cold-drawn steels is discussed. Two useful measures of machinability are provided by procedures which relate the solid-solution hardening effects of the alloying elements to carbon equivalents in hot-rolled steels, and the eutectoid-carbon lowering effects of the alloys to microstructures in annealed steels. Finally, attention is directed to the fact that cold working by extrusion improves the machinability of low-carbon steel.