: The Working Of Steel

Although it is possible to work steels cold, to an extent

depending upon their ductility, and although such operations are

commonly performed, forging usually means working heated steel.

Heating is therefore a vital part of the process.

Heating should be done slowly in a soaking heat. A soft lazy

flame with excess carbon is necessary to avoid burning the corners

of the bar or billet, and heavily scaling t
e surface. If the

temperature is not raised slowly, the outer part of the metal may

be at welding heat while the inner part is several hundred degrees

colder and comparatively hard and brittle.

The above refers to muffle furnaces. If the heating is done in

a small blacksmith's forge, the fire should be kept clean, and

remade at intervals of about two hours. Ashes and cinders should

be cleaned from the center down to the tuyere and oily waste and

wood used to start a new fire. As this kindles a layer of coke

from the old fire is put on top, and another layer of green coal

(screened and dampened blacksmiths' coal) as a cover. When the

green coal on top has been coked the fire is ready for use. As

the fuel burns out in the center, the coke forming around the edge

is pushed inward, and its place taken by more green coal. Thus the

fire is made up of three parts; the center where coke is burning

and the iron heating; a zone where coke is forming, and the outside

bank of green coal.