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Steel Making

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

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

The Influence Of Size
The size of the piece influences the physical properties obta...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

SULPHUR is another element (symbol S) which is always found i...

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

Blending The Compound
Essentially, this consists of the sturdy, power-driven separa...

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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 studied. These have been prepared by several of the
steel companies as a guide, but it must be remembered that the colors
and temperatures given are only approximate, and can be nothing

The Magnet Test.--The critical point can also be determined by
an ordinary horse-shoe magnet. Touch the steel with a magnet during
the heating and when it reaches the temperature at which steel fails
to attract the magnet, or in other words, loses its magnetism,
the critical point has been reached.

The work is heated up slowly in the furnace and the magnet applied
from time to time. The steel being heated will attract the magnet
until the heat reaches the critical point. The magnet is applied
frequently and when the magnet is no longer attracted, the piece
is at the lowest temperature at which it can be hardened properly.
Quenching slightly above this point will give a tool of satisfactory
hardness. The method applies only to carbon steels and will not
work for modern high-speed steels.

Next: Heat Treatment Of Gear Blanks

Previous: Hardening

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