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Steel Making

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

The Thermo-couple
With the application of the thermo-couple, the measurement of...

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

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

Manganese
Manganese adds considerably to the tensile strength of steel,...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

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

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

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

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

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

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

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

Double Annealing
Water annealing consists in heating the piece, allowing it to...

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



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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