VIEW THE MOBILE VERSION of Informational Site Network Informational
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

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

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

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

SILICON is a very widespread element (symbol Si), being an es...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

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

There is no mystery or secret about the proper annealing of d...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

Application To The Automotive Industry
The information given on the various parts of the Liberty eng...

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

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

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

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

Annealing Work
With the exception of several of the higher types of alloy s...

Rate Of Absorption


According to Guillet, the absorption of carbon is favored by those
special elements which exist as double carbides in steel. For example,
manganese exists as manganese carbide in combination with the iron
carbide. The elements that favor the absorption of carbon are:
manganese, tungsten, chromium and molybdenum those opposing it,
nickel, silicon, and aluminum. Guillet has worked out the effect
of the different elements on the rate of penetration in comparison
with steel that absorbed carbon at a given temperature, at an average
rate of 0.035 in. per hour.

His tables show that the following elements require an increased
time of exposure to the carburizing material in order to obtain
the same depth of penetration as with simple steel:

When steel contains Increased time of exposure
2.0 per cent nickel 28 per cent
7.0 per cent nickel 30 per cent
1.0 per cent titanium 12 per cent
2.0 per cent titanium 28 per cent
0.5 per cent silicon 50 per cent
1.0 per cent silicon 80 per cent
2.0 per cent silicon 122 per cent
5.0 per cent silicon No penetration
1.0 per cent aluminum 122 per cent
2.0 per cent aluminum 350 per cent

The following elements seem to assist the rate of penetration of
carbon, and the carburizing time may therefore be reduced as follows:

When steel contains Decreased time of exposure
0.5 per cent manganese 18 per cent
1.0 per cent manganese 25 per cent
1.0 per cent chromium 10 per cent
2.0 per cent chromium 18 per cent
0.5 per cent tungsten 0
1.0 per cent tungsten 0
2.0 per cent tungsten 25 per cent
1.0 per cent molybdenum 0
2.0 per cent molybdenum 18 per cent

The temperature at which carburization is accomplished is a very
important factor. Hence the necessity for a reliable pyrometer,
located so as to give the temperature just below the tops of the
pots. It must be remembered, however, that the pyrometer gives
the temperature of only one spot, and is therefore only an aid to
the operator, who must use his eyes for successful results.

The carbon content of the case generally is governed by the temperature
of the carburization. It generally proves advisable to have the
case contain between 0.90 per cent and 1.10 carbon; more carbon
than this gives rise to excess free cementite or carbide of iron,
which is detrimental, causing the case to be brittle and apt to chip.

T. G. Selleck gives a very useful table of temperatures and the
relative carbon contents of the case of steels carburized between
4 and 6 hrs. using a good charcoal carburizer. This data is as


At 1,500 deg.F., the surface carbon content will be 0.90 per cent
At 1,600 deg.F., the surface carbon content will be 1.00 per cent
At 1,650 deg.F., the surface carbon content will be 1.10 per cent
At 1,700 deg.F., the surface carbon content will be 1.25 per cent
At 1,750 deg.F., the surface carbon content will be 1.40 per cent
At 1,800 deg.F., the surface carbon content will be 1.75 per cent

To this very valuable table, it seems best to add the following
data, which we have used for a number of years. We do not know
the name of its author, but it has proved very valuable, and seems
to complete the above information. The table is self-explanatory,
giving depth of penetration of the carbon of the case at different
temperatures for different lengths of time:

Penetration -----------------------------
1,550 1,650 1,800
Penetration after 1/2 hr. 0.008 0.012 0.030
Penetration after 1 hr. 0.018 0.026 0.045
Penetration after 2 hr. 0.035 0.048 0.060
Penetration after 3 hr. 0.045 0.055 0.075
Penetration after 4 hr. 0.052 0.061 0.092
Penetration after 6 hr. 0.056 0.075 0.110
Penetration after 8 hr. 0.062 0.083 0.130

From the tables given, we may calculate with a fair degree of certainty
the amount of carbon in the case, and its penetration. These figures
vary widely with different carburizers, and as pointed out immediately
above, with different alloy steels.

Next: Carburizing Material

Previous: Surface Carburizing

Add to Add to Reddit Add to Digg Add to Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network

Viewed 2993