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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Hardening
The forgings can be hardened by cooling in still air or quen...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Impact Tests
Impact tests are of considerable importance as an indication ...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Annealing Of Rifle Components At Springfield Armory
In general, all forgings of the components of the arms manufa...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Critical Points
One of the most important means of investigating the properti...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

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

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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



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.





Next: Plant For Forging Rifle Barrels

Previous: Oil-hardening Steel



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