CPM S30V is a

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 Mart ...

(hardened) powder-made (sintered) wear and

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 engine ...

-resistant

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

developed by Dick Barber of

Crucible Industries Crucible Industries, commonly known as Crucible, was an American company which developed and manufactured specialty steels, and was the sole producer of a line of powder metallurgy, sintered steels known as Crucible Particle Metallurgy (CPM) steel ...

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 Hist ...

. Its chemistry promotes the formation and even distribution of

vanadium carbide Vanadium carbide is the inorganic compound with the formula . It is an extremely hard and 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 va ...

s, which are harder and more resistant to abrasion than chromium carbides. The powdered metallurgy process reduces the size of the carbides and gives the steel a very refined

grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...

, further improving

toughness In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing.carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

1.45%,

chromium Chromium is a chemical element; it has Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (mineralogy), lustrous, hard, and brittle transition metal. Chromium ...

14.00%,

vanadium Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...

4.00%, and

molybdenum Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals hav ...

2.00%. Barber received feedback from a number of other knife users and knifemakers such as

Sal Glesser Spyderco is an American cutlery company based in Golden, Colorado, producing knife, knives and knife sharpeners. Spyderco pioneered many features that are now common in folding knives, including the pocket clip, serrations, and the opening hole. ...

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 producin ...

, Tony Marfione, Phil Wilson, William Harsey Jr., Tom Mayo, Jerry Hossom, and Paul Bos in the development of CPM S30V. CPM S30V is considered a premium-grade knife steel.

Buck Knives Buck Knives is an American knife brand and manufacturer founded in San Diego, California in 1947 as H.H. Buck and Son, and now located in Post Falls, Idaho. Company founder and family patriarch Hoyt Buck made his first knife in 1902, but did no ...

calls it "the absolute best blade steel available". Joe Talmadge claims it may be the ultimate high-end all-around stainless steel, for its high performance coupled with easier machinability 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. Crucible steel was first developed in the middle of the 1st millennium BCE in Sout ...

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 Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

, and reductions in both

Carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

(from 1.45% to 1.40%) and

Vanadium Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...

(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.

References

{{Reflist Ferrous alloys Stainless steel