HEAT TREATMENT OF STEEL
Blending The Compound
Essentially, this consists of the sturdy, power-driven separator
and fanning mill which separates the foreign matter from the compound
and elevates it into a large settling basin which is formed by
the top of the s...
Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at definite
rates in order to change its physical condition. Many objects may
be attained by correct heat treatment, but nothing much can be
expected unless the ...
One of the most important means of investigating the properties of
pure metals and their alloys is by an examination of their heating
and cooling curves. Such curves are constructed by taking a small
piece and obse...
Steel is hardened by quenching from above the upper critical. Apparently
the quick cooling prevents the normal change back to definite and
sizeable crystals of ferrite and cementite. Hardness is associated
Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to have
accurate knowledge as to the heat being used in either forging or
hardening steels, a color chart will be of considerable assistance
if carefully studi...
Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gear
Manufacturers' Association at White Sulphur Springs, W. Va., Apr.
Great advancement has been made in the heat treating and hardening of
With the exception of several of the higher types
of alloy steels, where the percentages of special elements run quite
high, which causes a slight air-hardening action, the carburizing
steels are soft enough for ma...
Process Of Carburizing
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 co...
Effects Of Proper Annealing
Proper annealing of low-carbon steels
causes a complete solution or combination to take place between
the ferrite and pearlite, producing a homogeneous mass of small
grains of each, the grains of the pearlite being...
Temperature For Annealing
Theoretically, annealing should be
accomplished at a temperature at just slightly above the critical
point. However, in practice the temperature is raised to a higher
point in order to allow for the solution of the...
Care In Annealing
Not only will benefits in machining be found
by careful annealing of forgings but the subsequent troubles in
the hardening plant will be greatly reduced. The advantages in
the hardening start with the carburizing o...
The Influence Of Size
The size of the piece influences the physical properties obtained in
steel by heat treatment. This has been worked out by E. J. Janitzky,
metallurgical engineer of the Illinois Steel Company, as follows:
Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company,
Syracuse, N. Y., runs day and night, and besides handling all the
hardening of tools, parts of jigs, fixtures, special machines and
Forgings which are too hard to machine are put
in pots with a little charcoal to cause a reducing atmosphere and
to prevent scale. The covers are then luted on and the pots placed
in the furnace. Carbon steel from ...
The heat-treating department occupies an
L-shaped building. The design is very practical, with the furnace
and the floor on the same level so that there is no lifting of
heavy pots. Fuel oil is used in all the furn...
The Packing Department
In Fig. 56 is shown the packing pots where
the work is packed. These are of malleable cast iron, with an internal
vertical flange around the hole A. This fits in a bell on the
end of the cast-iron pipe B, which is ...
Short Method Of Treatment
In the new method, the packed pots are
run into the case-hardening furnaces, which are heated to 1,600 deg.F.
On the insertion of the cold pots, the temperature naturally falls.
The amount of this fall is dependent...
The heating at 1,600 deg.F. gives the first heat treatment
which refines the core, which under the former high heat (1,700 deg.F.)
was rendered coarsely crystalline. All the gears, including the
scrap gears, are qu...
Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel
gears are carburized separately owing to the difference in time
necessary for their carburization. Practically all printed information
on the subject is to the effect that nickel steel ...
Testing And Inspection Of Heat Treatment
The hard parts of the
gear must be so hard that a new mill file does not bite in the
least. Having passed this file test at several points, the gears go
to the center-punch test. The inspector is equipped with a wo...
Temperature Recording And Regulation
Each furnace is equipped
with pyrometers, but the reading and recording of all temperatures
are in the hands of one man, who occupies a room with an opening
into the end of the hardening department. The opening is ...
Hardening a gear is accomplished as follows:
The gear is taken from the furnace by the furnaceman and placed in
the lower die, surrounding the centering jaws, as shown at H in
Fig. 62 and C in Fig. 63. Air is then ...
Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized
and pushed on malleable-iron differential-case hubs. Formerly,
these sleeves were given two treatments after carburization in
order to refine the case and the core, and then sent t...
Cyanide Bath For Tool Steels
All high-carbon tool steels are
heated in a cyanide bath. With this bath, the heat can be controlled
within 3 deg. The steel is evenly heated without exposure to the
air, resulting in work which is not warped and o...
Drop Forging Dies
The kind of steel used in the die of course influences the heat
treatment it is to receive, but this also depends on the kind of
work the die is to perform. If the die is for a forging which is
machined all over an...
S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat treatments
to suit different steels and varying conditions. These have already
been referred to on pages 39 to 41 in connection with the different