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Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

Conclusions
Martien was probably never a serious contender for the honor ...

Molybdenum
Molybdenum steels have been made commercially for twenty-five...

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

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

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

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

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

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

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

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

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

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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

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

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

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

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



Silicon






Category: COMPOSITION AND PROPERTIES OF STEEL

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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