Carbon easily machinable steels

P-6 4 4 2 2 3 3 4 4 Easily machinable. Welds, repairs wen. Low carbon steel - not dimensionally stable in heal treatment. 

Medium- and high-carbon steels having a microstructure containing even coarse pearlite may still be too hard to machine or plastically deform conveniently. These steels, and in fact any steel, may be heat-treated or annealed to develop the spheroidite structure as described in Section 10.5. Spheroidized steels have a maximum softness and ductility and are easily machined or deformed. The spheroidizing heat treatment, during which there is a coalescence of the Fc3C to form the spheroid particles, can take place by several methods, as follows ... 

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