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Steel Making

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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

Annealing
ANNEALING can be done by heating to temperatures ranging from...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

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

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Furnace Data
In order to give definite information concerning furnaces, fu...

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

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...

Chromium
Chromium when alloyed with steel, has the characteristic func...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

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

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

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



Drop Forging Dies






Category: HEAT TREATMENT OF STEEL

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 and does not have to be especially close to size,
where a variation of 1/16 in. is not considered excessive, a low
grade steel will be perfectly satisfactory.

In cases of fine work, however, where the variation cannot be over
0.005 to 0.01 in. we must use a fine steel and prevent its going
out of shape in the heating and quenching. A high quality crucible
steel is suggested with about the following analysis: Carbon 0.75
per cent, manganese 0.25 per cent, silicon 0.15 per cent, sulphur
0.015 per cent, and phosphorus 0.015 per cent. Such a steel will
have a decalescent point in the neighborhood of 1,355 deg.F. and for
the size used, probably in a die of approximately 8 in., it will
harden around 1,450 deg.F.

To secure best results care must be taken at every step. The block
should be heated slowly to about 1,400 deg.F., the furnace closed tight
and allowed to cool slowly in the furnace itself. It should not
soak at the high temperature.

After machining, and before it is put in the furnace for hardening,
it should be slowly preheated to 800 or 900 deg.F. This can be done in
several ways, some putting the die block in front of the open door
of a hardening furnace and keeping the furnace at about 1,000 deg.F.
The main thing is to heat the die block very slowly and evenly.

The hardening heat should be very slow, 7 hr. being none too long
for such a block, bringing the die up gradually to the quenching
temperature of 1,450 deg.. This should be held for 1/2 hr. or even a
little more, when the die can be taken out and quenched. There
should be no guess work about the heating, a good pyrometer being
the only safe way of knowing the correct temperature.

The quenching tank should be of good size and have a spray or stream
of water coming up near the surface. Dip the die block about 3 in.
deep and let the stream of water get at the face so as to play
on the forms. By leaving the rest of the die out of the water,
moving the die up and down a trifle to prevent a crack at the line
of immersion, the back of the block is left tough while the face
is very hard. To overcome the tendency to warp the face it is a
good plan to pour a little water on the back of the die as this
tends to even up the cooling. The depth to which the die is dipped
can be easily regulated by placing bars across the tank at the
proper depth.

After the scleroscope shows the die to be properly hardened, which
means from 98 to 101, the temper should be drawn as soon as convenient.
A lead pot in which the back of the die can be suspended so as
to heat the back side, makes a good method. Or the die block can
be placed back to the open door of a furnace. On a die of this
size it may take several hours to draw it to the desired temper.
This can be tested while warm by the scleroscope method, bearing
in mind that the reading will not be the same as when cold. If
the test shows from 76 to 78 while warm, the hardness when cold
will be about 83, which is about right for this work.





Next: S A E Heat Treatments

Previous: Cyanide Bath For Tool Steels



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