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Steel Making

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

Care In Annealing
Not only will benefits in machining be found by careful anne...

Heating
Although it is possible to work steels cold, to an extent de...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

The Modern Hardening Room
A hardening room of today means a very different place from ...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

Hardening
Steel is hardened by quenching from above the upper critical....

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Temperatures To Use
As soon as the temperature of the steel reaches 100 deg.C. (...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Pyrometry And Pyrometers
A knowledge of the fundamental principles of pyrometry, or th...

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Placing Of Pyrometers
When installing a pyrometer, care should be taken that it re...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...



Chrome-nickel Steel






Category: THE FORGING OF STEEL

Forging heat of chrome-nickel steel depends
very largely on the percentage of each element contained in the
steel. Steel containing from 1/2 to 1 per cent chromium and from
1-1/2 to 3-1/2 per cent nickel, with a carbon content equal to
the chromium, should be heated very slowly and uniformly to
approximately 1,600 deg. F., or salmon color. After forging, reheat
the steel to about 1,450 deg. and cool slowly so as to remove forging
strains. Do not attempt to harden the steel before such annealing.

A great deal of steel is constantly being spoiled by carelessness
in the forging operation. The billets may be perfectly sound, but
even if the steel is heated to a good forging heat, and is hammered
too lightly, a poor forging results. A proper blow will cause the
edges and ends to bulge slightly outwards--the inner-most parts
of the steel seem to flow faster than the surface. Light blows
will work the surface out faster; the edges and ends will curve
inwards. This condition in extreme cases leaves a seam in the axis
of the forging.

Steel which is heated quickly and forging begun before uniform
heat has penetrated to its center will open up seams because the
cooler central portion is not able to flow with the hot metal
surrounding it. Uniform heating is absolutely necessary for the
best results.

Figure 16 shows a sound forging. The bars in Fig. 17 were burst
by improper forging, while the die, Fig. 18, burst from a piped
center.

Figure 19 shows a piece forged with a hammer too light for the size
of the work. This gives an appearance similar to case-hardening,
the refining effect of the blows reaching but a short distance
from the surface.

While it is impossible to accurately rate the capacity of steam
hammers with respect to the size of work they should handle, on
account of the greatly varying conditions, a few notes from the
experience of the Bement works of the Niles-Bement-Pond Company
will be of service.




For making an occasional forging of a given size, a smaller hammer
may be used than if we are manufacturing this same piece in large
quantities. If we have a 6-in. piece to forge, such as a pinion or
a short shaft, a hammer of about 1,100-lb. capacity would answer
very nicely. But should the general work be as large as this, it
would be very much better to use a 1,500-lb. hammer. If, on the
other hand, we wish to forge 6-in. axles economically, it would
be necessary to use a 7,000- or 8,000-lb. hammer. The following
table will be found convenient for reference for the proper size
of hammer to be used on different classes of general blacksmith
work, although it will be understood that it is necessary to modify
these to suit conditions, as has already been indicated.




Diameter of stock Size of hammer
3-1/2 in. 250 to 350 lb.
4 in. 350 to 600 lb.
4-1/2 in. 600 to 800 lb.
5 in. 800 to 1,000 lb.
6 in. 1,100 to 1,500 lb.

Steam hammers are always rated by the weight of the ram, and the
attached parts, which include the piston and rod, nothing being
added on account of the steam pressure behind the piston. This makes
it a little difficult to compare them with plain drop or tilting
hammers, which are also rated in the same way.



Steam hammers are usually operated at pressures varying from 75
to 100 lb. of steam per square inch, and may also be operated by
compressed air at about the same pressures. It is cheaper, however,
in the case of compressed air to use pressures from 60 to 80 lb.
instead of going higher.

Forgings must, however, be made from sound billets if satisfactory
results are to be secured. Figure 20 shows three cross-sections
of which A is sound, B is badly piped and C is worthless.





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Previous: Oil-hardening Steel



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