Process Of Carburizing

: The Working Of Steel

Carburizing imparts a shell of high-carbon

content to a low-carbon steel. This produces what might be termed

a dual steel, allowing for an outer shell which when hardened

would withstand wear, and a soft ductile core to produce ductility

and withstand shock. The operation is carried out by packing the

work to be carburized in boxes with a material rich in carbon and

maintaining the box so charged at a temperature in ex
ess of the

highest critical point for a length of time to produce the desired

depth of carburized zone. Generally maintaining the temperature

at 1,650 to 1,700 deg. F. for 7 hr. will produce a carburized zone

1/32 in. deep.

Heating to a temperature slightly above the highest critical point

and cooling suddenly in some quenching medium, such as water or oil

hardens the steel. This treatment produces a maximum refinement

with the maximum strength.

Drawing to a temperature below the highest critical point (the

temperature being governed by the results required) relieves the

hardening strains set up by quenching, as well as the reducing

of the hardness and brittleness of hardened steel.