martensitic
Martensite is a very hard form of steel crystalline structure. It is named after German metallurgist Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation.
Properties
Marte ...
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...
Crucible Industries
Crucible Industries, commonly known as Crucible, is an American company which develops and manufactures specialty steels, and is the sole producer of Crucible Particle Metallurgy (CPM) steels. The company produces high speed, stainless and tool ...
in collaboration with knifemaker
Chris Reeve
Christopher Stanley Reeve (born December 4, 1953) is a South African-American knife maker, recognized as one of the most influential people in knife making history.Shackleford, Steve, Blade Magazine, “30 Most Influential People in Blade His ...
. Its chemistry promotes the formation and even distribution of
vanadium carbide
Vanadium carbide is the inorganic compound with the formula V C. It is an extremely hard refractory ceramic material. With a hardness of 9-9.5 Mohs, it is possibly the hardest metal-carbide known. It is of interest because it is prevalent in v ...
s, which are harder and more effective at cutting than
chromium carbide
Chromium(II) carbide is a ceramic compound that exists in several chemical compositions: Cr3C2, Cr7C3, and Cr23C6. At standard conditions it exists as a gray solid. It is extremely hard and corrosion resistant. It is also a refractory compound, ...
s. These vanadium carbides give the steel a very refined grain, further improving the sharpness and
toughness
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. It contains
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
1.45%, chromium 14.00%, vanadium 4.00%, and molybdenum 2.00%. Barber received feedback from a number of other knife users and knifemakers such as Sal Glesser,
Ernest Emerson
Ernest R. Emerson (born March 7, 1955) is an American custom Knifemaking, knifemaker, Martial arts, martial artist, and edged-weapons expert. Originally an engineer and machinist in the aerospace industry, Emerson became a knifemaker by produci ...
William Harsey Jr.
William Harsey Jr. (born 1955) is an American knifemaker and designer who works with several knife companies, including Gerber Legendary Blades, Lone Wolf Knives, Spartan Blades, Ruger/CRKT, Fantoni, and Chris Reeve Knives.
Personal history
H ...
, Tom Mayo, Jerry Hossom, and Paul Bos in the development of CPM S30V.
CPM S30V is considered a premium grade knife steel. It is so expensive that it strongly affects the price of the knife, and is largely used in higher-end production and custom knives.
Buck Knives
Buck Knives is an American knife manufacturer founded in Mountain Home, Idaho and now located in Post Falls, Idaho. The company has a long history through five generations of the Buck family from 1902 to the present day. Buck Knives primarily man ...
calls it "the absolute best blade steel available". Joe Talmadge claims it might be the ultimate high-end all-around stainless steel, due to high performance coupled with easier machinability and sharpenability than the other steels in this class.
Properties
Composition
Physical properties
Coefficient of thermal expansion
CPM-S35VN
In 2009,
Crucible Steel
Crucible steel is steel made by melting pig iron (cast iron), iron, and sometimes steel, often along with sand, glass, ashes, and other fluxes, in a crucible. In ancient times steel and iron were impossible to melt using charcoal or coal fires ...
introduced an update to CPM-S30V to meet the needs of renowned knife maker Chris Reeve that they called CPM-S35VN. The addition of 0.5% Niobium, and reductions in both
Carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
from (1.45% to 1.40%) and Vanadium (from 4% to 3%) produced an alloy with 25% increase in measured Charpy V-notch toughness over S30V (Crucible claims 15-20% improvement). Working chefs and outdoor survivalists laud the improved toughness of S35VN, which greatly reduces the micro-bevel chipping that tends to plague S30V in rough use. In these kinds of applications the advantage of an S35VN blade over S30V is quick honing with a strop or steel stick in lieu of needing to remove metal and reform the edge. In light use, edge-holding and stainless properties between S35VN versus S30V are thought to be roughly the same, and performance will often be affected nearly as much by the applied heat treatment, blade design, and the edge geometry as the differences in metal chemistry.
Around this same time period, Carpenter CTS-XHP and Uddeholm Elmax became more widely available for cutlery usage. These powdered steels use a different process than Crucible, but they are also high-end stainless steels (with high-chromium and high-vanadium levels similar to S30V and S35VN) intended to compete with CPM-S30V and CPM-S35VN.