
466 Fundamentals of Machining Processes
obtain a denite microstructure; to change hardness; or to make
other changes that directly affect machinability.
4. Chemical composition: Chemical composition is a major factor in
determining material machinability. The effect of composition
depends on how the elements make up an alloy. Certain generaliza-
tions about chemical composition of steels in relation to machinabil-
ity can be made, but nonferrous alloys are too numerous so that such
generalizations are not valid.
5. Fabrication: Whether a metal has been hot rolled, cold rolled, cold
drawn, cast, or forged, it will affect its grain size, ducti