Steel Production
& Properties
The following provides a very brief overview of steel treatment
and properties:
By definition, steel is a combination of iron and
no more that 2% carbon. Steel is alloyed with various other elements
that combine to produce special properties. Once a particular
alloy combination (or steel type) is selected, specific procedures
are used to maximize the unique qualities required for that steel
to perform. Generally speaking, the process for converting a steel
alloy into a premium knife steel is heat treating.
Heat treatment is the most important stage in the
evolution of an alloy into a performance knife steel. The first
step in the heat treatment process is to reach a critical temperature.
This temperature is held for a specific amount of time (depending
on the steel being hardened) and causes the steel to become austenetized.
Heat treatment is one of the many factors that determines the
grain size of the steel (a fine grain structure is more
desireable for knife blades because it improves edge retention
and enhances blade finish).
Next, the steel is quenched to achieve its
maximum level of hardness.
At this point, the steel is too hard and brittle for practical
use and thus tempering is of key importance in bringing
the steel to its ideal hardness level (different knife steels
perform best at different levels of hardness). Tempering also
increases wear resistance and toughness properties. When
tempering, it is important to understand the interaction between
hardness and toughness. An increase in yield strength and
tensile strength and a decrease in impact strength
and ductility. An increase in toughness is usually accompanied
by the opposite effect (i.e. an increase in toughness and ductility
and a decrease in yield strength and tensile strength). Therefore,
high-impact knifes such as swords and machetes would benefit from
a softer blade (to avoid blade breakage), while low-impact knifes
such as pocket knifes may benefit from a harder blade (to improve
wear resistance). Once tempering is complete, the final hardness
of the steel can be determined using a Rockwell Test.
For more detailed information of
the above processes and properties, we recommend the following
references that were used to compile this information: Metallurgy
Fundamentals by D.A. Brandt (published by Goodheart-Wilcox) and
Heat Treaters Guide by P.M. Unterweiser (published by ASM).
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