CPM S30V steel

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CPM S30V is a martensitic (hardened) powder-made (sintered) wear and corrosion resistant stainless steel developed by Dick Barber of Crucible Industries in collaboration with knifemaker Chris Reeve.[1][2] Its chemistry promotes the formation and even distribution of vanadium carbides, which are harder and more effective at cutting than chromium carbides.[1] These vanadium carbides give the steel a very refined grain, further improving the sharpness and toughness.[3] Despite some difficulties with a consistent heat-treat, knifemakers use CPM S30V because its composition makes it easier to grind than other powder steels although the carbides still wear down the grinder belts considerably.[4] Its composition is as follows: Carbon 1.45%, Chromium 14.00%, Vanadium 4.00%, Molybdenum 2.00%.[1] Barber received feedback from a number of other knife users and knifemakers such as Sal Glesser, Ernest Emerson, 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. 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 calls it "the absolute best blade steel available".[5] 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.[6]

Properties[edit]

Composition[edit]

 A comparison between CPM and other process's carbide distribution.
Carbon Chromium Vanadium Molybdenum
1.46% 14.00% 4.00% 2.00%

Physical Properties[edit]

Elastic Modulus Density
32 X 106 psi 0.27 lbs./in3
(221 GPa) (7.47 g/cm3)

Coefficient of Thermal Expansion

°F °C in/in/°F mm/mm/°C
... ... ... ...
... ... ... ...
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CPM-S35VN[edit]

In 2009, CPM-S35VN was introduced by Crucible Steel and Chris Reeve as an incremental (minor) update of CPM-S30V. The addition of Niobium and finer grain structure than S30V increases toughness and ease of sharpening. Edge-holding and stainless properties are roughly the same (roughly same carbon, chromium, moly, and vanadium levels). The differences between CPM-S35VN versus CPM-S30V are arguably minimal when compared to the variances in properties found within each respective steel, which is dependent upon the heat treatment that specific blade is given, the blade design itself, and the edge geometry of that particular blade. Around this 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[edit]

  1. ^ a b c "CPM S30V". Crucible Industries LLC. Archived from the original on 2010-10-11. Retrieved 2010-10-11. 
  2. ^ Gardner, James (June 2005). "Duel of the Titans: two exceptional folders exemplify state-of-the-art". Guns Magazine 27 (6): 145–151. 
  3. ^ Ward, C. (2008), "An Edge in the Kitchen", Harper Collins, p.33-34, ISBN 978-0-06-118848-0
  4. ^ Mayo, Tom. "Technical and General Info". Mayo Knives Hawaii. Retrieved 2008-02-05. 
  5. ^ "Types of Steel". 
  6. ^ Talmadge, Joe (2005). "Knife steel FAQ". zknives.com.