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

Corrosion
This steel like any other steel when distorted by cold worki...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

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

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

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

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

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

Steel Worked In Austenitic State
As a general rule steel should be worked when it is in the a...

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

Vanadium
Vanadium has a very marked effect upon alloy steels rich in c...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...



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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