Machined
parts constitute a range of shapes and forms that may require several heat
treatments to achieve specific mechanical properties. Stress relieving is utilized
prior to machining to stabilize part dimensions.
Full annealing and sub-critical
annealing may be used to soften the part for aggressive machining or
broaching operations.
After
machining, carbon and alloy steel parts may be through hardened
to achieve specific end use properties. Carbon
steel parts may also be carbonitride or carburize surface
hardened. The final dimensions may
be restored after heat treatment by finish grinding.
Some heat treatment processes may be tailored to hold dimensions to
reduce or eliminate final grinding. Some
machined parts are made from precipitation hardening alloys which require only age
hardening after machining to achieve medium strength properties.
Machined
parts may be selectively heat treated by induction
or flame hardening.
Post heat treatment finishing is typically accomplished by glass
bead blasting.