Glossary


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Vacuum Degassing
An advanced steel refining facility that removes oxygen, hydrogen and
nitrogen under low pressures (in a vacuum) to produce ultra-low-carbon
steel for demanding electrical and automotive applications. Normally
performed in the ladle, the removal of dissolved gases results in cleaner,
higher-quality, more pure steel (see Ladle Metallurgy).
Varnish
A colorless, transparent finish applied over a decorative system to protect
the substrate and inks and improve gloss
Vickers Hardness Test
An indentation hardness test employing a 136o diamond pyramid indenter
(Vickers) and variable loads, enabling the use of one hardness scale for
all ranges of hardness- from very soft lead to tungsten carbide. Also known
as diamond pyramid hardness test.
Vinyl
Vinyl resins are co-polymers with vinyl chloride and vinyl acetate as the
major film formers. They offer toughness, flexibility, and adhesion and are
considered flavour-free.
Voss Leveler
A set of rolls that flattens and stretches the strip into a flat shape.
Vacuum Oxygen Decarburization (VOD)
What Process for further refinement of stainless steel through reduction of
carbon content.
Why The amount of carbon in stainless steel must be lower than that in
carbon steel or lower alloy steel (i.e., steel with alloying element
content below 5%). While electric arc furnaces (EAF) are the conventional
means of melting and refining stainless steel, VOD is an economical
supplement, as operating time is reduced and temperatures are lower than in
EAF steel making. Additionally, using VOD for refining stainless steel
increases the availability of the EAF for melting purposes.
How Molten, unrefined steel is transferred from the EAF into a separate
vessel, where oxygen is blown from the top to oxidise the carbon present in
the steel bath and thus reduce the carbon content as per permissible limit
in stainless steel chemistry. Being an exothermic process, the heat
generated maintains the fluidity of steel. Argon is blown from the bottom
to accentuate the stirring of the bath and homogenise the temperature,
while oxygen enters from the top of the vessel. Substantial quantities of
undesirable gases escape from the steel and are drawn off by a vacuum pump.
Alloys and other additives are then mixed in to refine the molten steel
further.
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