Knives and Knife Sharpeners
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Knife Anatomy
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Steel Element Information
Carbon (C)
- Increases edge retention and raises tensile strength.
- Increases hardness and improves resistance to wear and abrasion.
Chromium (CR)
- Increases hardness, tensile strength, and toughness.
- Provides resistance to wear and corrosion.
Cobalt (CO)
- Increases strength and hardness, and permits quenching in higher temperatures.
- Intensifies the individual effects of other elements in more complex steels.
Copper (CU)
- Increases corrosion resistance.
Manganese (MN)
- Increases hardenability, wear resistance, and tensile strength.
- Deoxidizes and degasifies to remove oxygen from molten metal.
- In larger quantities, increases hardness and brittleness.
Molybdenum (MO)
- Increases strength, hardness, hardenability, and toughness.
- Improves machinability and resistance to corrosion.
Nickel (NI)
- Adds strength and toughness
.
Nitrogen (N)
- Used
in place of carbon for the steel matrix. The Nitrogen atom will
function in a similar manner to the carbon atom but offers unusual
advantages in corrosion resistance.
Phosphorus (P)
- Improves strength, machinability, and hardness.
- Creates brittleness in high concentrations.
Silicon (SI)
- Increases strength.
- Deoxidizes and degasifies to remove oxygen from molten metal.
Sulfur (S)
- Improves machinability when added in minute quantities.
Tungsten (W)
- Adds strength, toughness, and improves hardenability.
Vanadium (V)
- Increases strength, wear resistance, and increases toughness.
Steel Production And 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 alloy1
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 theat reating2.
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.3 This temperature is held for a specific amount of time (depending on the steel being hardened) and causes the steel to become austenetized.4 Heat treatment is one of the many factors that determines the grain size5
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 quenched6 to achieve its maximum level of hardness.7 At this point, the steel is too hard and brittle for practical use and thus tempering8
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 toughness9 properties. When tempering, it is important to understand the interaction between hardness and toughness. An increase in yield strength10 and tensile strength11 and a decrease in impact strength12 and ductility.13
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.14
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).
- Alloy
- A
material that is dissolved in another metal in a solid solution; a
material that results when two or more elements combine in a solid
solution.
- Austenetized
- The basic steel structure state in which an alloying is uniformly dissolved into iron.
- Critical Temperature
- The temperature at which steel changes its structure to austenite in preparation for hardening.
- Ductility
- The tendency of a material to stretch or plastically deform appreciably before fracturing.
- Grain Size
- The
physical size of the austenite grains during austenizing. The actual
size can vary due to thermal, time and forging considerations.
- Hardness
- The resistance of a steel to deformation or penetration analogous to strength.
- Heat Treating
- Heating
and cooling metal to prescribed temperature and the limits for the
purpose of changing the properties and behavior of the metal.
- Impact Strength
- The ability of a material to resist cracking due to a sudden force.
- Quenched Rapidly cooled from the critical temperature using water, oil, air or other means.
- Rockwell Test
- A
measurement of steel hardness based on the depth of penetration of a
small diamond cone pressed into the steel under a constant load.
- Tempering
- Reheating
to a lower temperature after quenching for the purpose of slightly
softening the steel, precipitating carbides, stress relieving.
- Tensile Strength
- Indicated by the force at which a material breaks due to stretching.
- Toughness
- The ability of a material to resist shock or impact.
- Yield Strength
- The
point at which a steel becomes permanently deformed; the point at which
the linear relationship of stress to strain changes on a Stress/Strain
curve.
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Tactical Folding Knives
Advance your self-defense skills to a new level by learning personal
hand-to-hand combat with tactical folding knives. Tactical folding
knives are specifically designed and manufactured for self-defense. The
blade folds back into the handle and can be opened quickly using one
hand with a thumb stud. Folding tactical knives also include blade
locks to prevent the blade from accidentally closing and harming the
owner.
Modern Features Of Tactical Folding Knives
Tactical folding knives, also known as lock backs, or liner locks have
a couple of modern features that have become popular since the late
80's to early 90's. A modern feature that many people enjoy is the
thumb stud in the blade that makes it easier to push the knife open
with the thumb. Pocket clips also have become quite popular for
tactical folding knives due to the quick access they allow if needed in
an emergency.
Sharpening Tactical Folding Knives
You can sharpen tactical folding knives by holding them at 22 degrees
for a sharp knife or 12-15 degrees for a very sharp knife. The type of
sharpening stone used can also affect the sharpness of the blade. Many
prefer to use a clamp-style system that has pre-defined angles to
ensure accurate sharpening.
Traditional stones can be used to sharpen tactical folding knives and
they are known as Arkansas stones, which come in soft (coarse) and hard
(fine) varieties. Some prefer to use ceramic stones due to the fact
that they do not wear like natural stones and they do not require oil
like the Arkansas stone does.
When sharpening tactical folding knives you may require oil to lift the
metal dust off of the stone. Ceramic stones do not require oil as they
can be cleaned with detergent.
When you are done sharpening a tactical folding knife you may want to
use a technique called "stropping." This is performed with a leather
strap that has abrasive compounds in it. This can be used on a tactical
folding knife that is still sharp, but not as sharp as it once was.
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DMT Sharpening Surfaces
Interrupted diamond surfaces
These products carry signature
polka-dot pattern surfaces. The polka dots are slightly recessed so
that during sharpening the metal fines (known as swarf) and small
amount of material that is being removed will fall into the polka dots
and remain out of the way of the sharpening surface keeping the
sharpening surface performing.
Continuous diamond surfaces
Continuous diamond surface sharpeners are preferred when sharpening
small-pointed tools and can be used for knife and tool sharpening,
honing and deburring as well. On an interrupted surface the point of a
small tool may get caught in a recess and damage the surface of the
sharpener. It is recommended that you use a continuous diamond or
ceramic surface for these types of tools.
Ceramic surface
Ceramic Diamond Shrpeners are the latest innovation and are the perfect
compliment to your assortment of sharpening tools. The patented
CeraFuse™ process transfoms the surface of aluminum to an extremely
hard dense aluminum oxide that has the same properties of solid ceramic
materials. With a finer grit than the bonded diamond products, they are
unbreakable, wear resistant, light and non-porous. The ceramic
sharpeners are the next step to achieving a polished edge.
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What Is A Diamond Sharpening Stone?
Diamond sharpening stones are sharpening stones coated in
micro-diamonds. What's inside the "stone" isn't necessarily a chunk of
rock. It could be metal or a composite stone manufactured mechanically.
Diamond is one of the hardest substances on Earth. By coating a stone
in diamond powder, it ensures you'll be able to sharpen even the
strongest blade, and the porous surface provides an escape route for
filings that come off your blade. This keeps gunk from building up on
the stone and hampering its effectiveness. DMT Sharpening Stones are
some of the most popular of diamond sharpening stones.
How to choose your sharpening stone
There are several choices, but few as universally relied upon as the
low-tech sharpening stone. Diamond stones which have a very fine grit,
are used on knives that only need touched up. For duller blades,
approach it much like you're using sandpaper on a block of wood:
coarse-grit stones first (grits of 400 or less); then progressively
finer ones (600 and above). For a serrated blade, you're going to need
a cone-shaped taper sharpener which will be made of the same material
as a regular stone. For big tools: sharpening pads. Some enthusiasts
swear by using oil to sharpen their blades, others go with water, or –
in a pinch – saliva.
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