ets are carefully
inspected and all surface defects ground or chipped. The hammered
billets are again slowly heated and receive a second hammering,
known as "cogging." The billet resulting therefrom is known as
a "cogged" billet and is of the proper size for the rolling mill
or for the finishing hammer.

Although it is not considered good mill practice, some manufacturers
who have a large rolling mill perform the very important cogging
operation in the rolling mill instead of under the hammer. Cogging
in a rolling mill does not break up and distribute the carbides and
tungstides as efficiently as cogging under the hammer; another objection
to cogging in the rolling mill is that there is no opportunity to
chip surface defects developed as they can be under the trained eye
of a hammer-man, thereby eliminating such defects in the finished
billet.

The rolling of high-speed steel is an art known to very few. The
various factors governing the proper rolling are so numerous that
it is necessary for each individual rolling mill to work out a
practice that gives the best results upon the particular analysis
of steel it makes. Important elements entering into the rolling
are the heating and finishing temperatures, draft, and speed of
the mill. In all of these the element of time must be considered.

High-speed steel should be delivered from the rolling mill to the
annealing department free from scale, for scale promotes the formation
of a decarbonized surface. In preparation of bars for annealing,
they are packed in tubes with a mixture of charcoal, lime, and
other material. The tubes are sealed and placed in the annealing
furnace and the temperature is gradually raised to about 1,650 deg.F.,
and held there for a sufficient length of time, depending upon the
size of the bars. After very slow cooling the bars are removed
from the tubes. They should then show a Brinnell number of between
235 and 275.

The inspection department ranks with the chemical and metallurgical
departments in safeguarding the quality of the product. It inspects
all finished material from the standpoint of surface defects, hardness,
size and fracture. It rejects such steel as is judged not to meet
the manufacturer's standard. The inspection and metallurgical
departments work hand in hand, and if any department is not functioning
properly it will soon become evident to the inspectors, enabling
the management to remedy the trouble.

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