Leaded Steels
When added to steel, lead does not go into solution but exists in a very finely divided state along the grain boundries. It greatly assists machinability as it acts as a lubricant between the steel and the tool face. Lead is normally added in amounts between 0.15-0.35% and when combined with similar amounts of sulphur, optimum machinability is attained as in such steel as B 970 230M07 Pb.
