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Steel Making

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

PHOSPHORUS is an element (symbol P) which enters the metal fr...

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

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Piston Pin
The piston pin on an aviation engine must possess maximum res...

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

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

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

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

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

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

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

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

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

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

Crucible Steel
Crucible steel is still made by melting material in a clay or...



SILICON is a very widespread element (symbol Si), being an essential
constituent of nearly all the rocks of the earth. It is similar to
carbon in many of its chemical properties; for instance it burns
very readily in oxygen, and consequently native silicon is unknown--it
is always found in combination with one or more other elements.
When it bums, each atom of silicon unites with two atoms of oxygen
to form a compound known to chemists as silica (SiO2), and to the
small boy as sand and agate.

Iron ore (an oxide of iron) contains more or less sand and dirt
mixed in it when it is mined, and not only the iron oxide but also
some of the silicon oxide is robbed of its oxygen by the smelting
process. Pig iron--the product of the blast furnace--therefore
contains from 1 to 3 per cent of silicon, and some silicon remains
in the metal after it has been purified and converted into steel.

However, silicon, as noted above, burns very readily in oxygen,
and this property is of good use in steel making. At the end of
the steel-making process the metal contains more or less oxygen,
which must be removed. This is sometimes done (especially in the
so-called acid process) by adding a small amount of silicon to
the hot metal just before it leaves the furnace, and stirring it
in. It thereupon abstracts oxygen from the metal wherever it finds
it, changing to silica (SiO2) which rises and floats on the surface
of the cleaned metal. Most of the silicon remaining in the metal
is an excess over that which is required to remove the dangerous
oxygen, and the final analysis of many steels show enough silicon
(from 0.20 to 0.40) to make sure that this step in the manufacture
has been properly done.

Next: Manganese

Previous: Phosphorus

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