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[machinist] Knife Steel Composition Chart | Knife Informer
- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Knife Steel Composition Chart | Knife Informer
- Date: Sun, 6 Aug 2017 22:21:35 -0400
Knife Steel Composition Chart | Knife Informer
http://knifeinformer.com/knife-steel-composition-chart/
As an extension of our Guide to the Best Knife Steel, we’ve compiled the reference table below showing the most popular types of knife steel and their composition of the various elements. You can click on the column to sort the data accordingly.
Below the table you’ll find a summary of the most commonly used elements in steel production and their impact on the properties and overall quality of the steel.
Summary of key elements
Here is a useful summary of the alloying elements that are vital in knife production together with a brief description of their impact on the resulting steel’s properties.
Carbon (C)
Contributes: Hardness, Edge Retention. You’ll find carbon
in every form of steel. Essentially, it’s the element that turns the
basic metal iron into steel and plays a huge part in the hardening
process. Generally with increased levels of carbon you get a harder
steel, improved tensile strength, edge retention and overall resistance
to wear. Knife steels are typically described as “high carbon” if they
contain more than 0.5% carbon and these generally what you want to look
for in a knife steel. However, if manufacturers go over the top with
too much carbon it can make the steel brittle and also increases
proneness to corrosion.
Chromium (Cr)
Contributes: Corrosion Resistance. By adding chromium
to the steel it increases the resistance to oxidation and corrosion in
general. To be classified as “Stainless Steel” there should be at least
13% chromium (you’ll see others quote 11% or 12% but 13% is a safe
bet). Chromium is the key driver for carbide formation which lowers
brittleness but also adversely impacts edge retention. In addition to
improving the resistance to corrosion, chromium also improves
hardenability and tensile strength. Still, every steel is going to
corrode if left out in the elements for a prolonged period. Note also
that too much chromium can reduce toughness.
Molybdenum (Mo)
Contributes: Toughness.
Molybdenum will increase toughness which reduces the liklihood of
chipping. It also allows the steel to maintain its strength at high
temperatures which helps with how easy a blade is to produce in the
factory. Like chromium it is a driver of carbide formation but is used
typically in small relative quantities.
Nickel (Ni)
Contributes: Toughness.
Some manufacturers have chosen to add small quantities of Nickel to
increase toughness and strength especially at low temperatures which
basically limits distortion and cracking during the quenching phase of
heat treatment. Many knife makers claim it also reduces corrosion but
that is often disputed.
Vanadium (V)
Contributes: Toughness, Wear Resistance.
Vanadium is another element similar to Molybdenum that promotes
carbide formation (the hardest of all) and it adds wear resisting
properties to steels. Perhaps more importantly, vanadium produces a
very fine grain during the steel’s heat treatment process which improves
overall toughness. Some of the ultra-premium steels contain relatively
high levels of vanadium and allow for a super sharp edge.
Cobalt (Co)
Contributes: Hardness.
Adding very small amounts of cobalt can allow for quenching (i.e.
rapid cooling to achieve hardness) at higher temperatures and tends to
boost the effects of other elements in the more complicated steels. It
is not a carbide former in itself but certainly does promote the
achievement of overall hardness.
Manganese (Mn)
Contributes: Hardenability, Strength, Wear Resistance.
Another key element which assists with the hot working properties
making the knife more stable during quenching. Manganese will
contribute to increased hardness as well as tensile strength and
resistance to wear and tear. As with anything that increases hardness,
too much and the steel will be too brittle.
Silicon (Si)
Contributes: Hardenability, Strength.
Silicon adds to overall strength similar to the effects of Manganese,
making the manufacture of the steel far more stable. However, the real
value of Silicon is in de-oxidation and de-gasifying to remove oxygen.
Oxygen is unwelcomed in steel production because it leads to blowholes
or pitting.
Niobium (Nb)
Contributes: Toughness, Wear Resistance. Niobium is primarily used to aid fine grain structure which helps to improve the wear resistance and prevent chipping. Arguably the best known knife steel that capitalized on Niobium is CPM-S35VN which combined with carbon, introduced niobium carbides to aid wear resistance and edge chipping. The result is formidable edge retention.
Tungsten (W)
Tungsten forms carbides and will tend to improve resistance to wear and tear. It is usually added in conjunction with chromium or molybdenum for best results.
Other elements used less frequently include Aluminium (Al), Boron (B), Copper (Cu), Niobium (Nb), Nitrogen (N), Lead (Pb), Phosphorus (P).
- [machinist] Knife Steel Composition Chart | Knife Informer, Lawrence London, 08/06/2017
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