CPM 20CV steel, also known as M390 and 204P, is an established high-wear resistance stainless steel popular in the knife industry.
20CV unique alloy, featuring a high volume of hard vanadium carbides, gives 20CV unparalleled edge retention and durability.
In contrast, CPM S30V takes a more holistic approach, balancing wear resistance with improved toughness, corrosion resistance, and grindability.
20CV vs S30V Steel At A Glance
| Property | 20CV Steel | S30V Steel |
|---|---|---|
| Hardness | High hardness up to 63 HRC | Aim Hardness of 58-61 HRC |
| Wear Resistance | Exceptional edge retention and wear resistance. | Excellent wear resistance, though not quite at the level of 20CV. |
| Toughness | Reduced toughness compared to S30V steel. | Improved toughness compared to 20CV |
| Corrosion Resistance | Excellent corrosion resistance | Good corrosion resistance, but not quite as high as 20CV. |
| Ease of Sharpening | Difficult to grind and sharpe . | Slightly Easier to grind and sharpen than 20CV. |
Hardness
Hardness in knife steel is an important factor that directly affects aspects like edge retention, toughness and ease of sharpening.
20CV is a highly wear-resistant powder metallurgy stainless steel that can achieve very high hardness levels, up to 63 HRC.
S30V can be heat treated to a typical hardness range of 58-61 HRC, however, S30V is capable of reaching high hardness range of 63HRC too.
This high hardness and wear resistance is attributed to the large volume of hard vanadium carbides in the 20CV and S30V microstructure.
Toughness
The toughness of 20CV and S30V steels differs, with S30V having a slight advantage in toughness over 20CV.
20CV is designed primarily for maximum wear resistance and hardness, with high volume of vanadium carbides reducing toughness.
S30V knife steel is engineered to offer a balance of toughness, wear resistance, and corrosion resistance.
The transverse toughness of S30V, as measured by Charpy impact testing, is significantly higher than steels like 440C or 154CM.
This improved toughness makes S30V less susceptible to chipping or breaking, especially in larger blade designs.
Edge Retention
20CV and S30V exhibit excellent edge retention and wear resistance, though 20CV holds a slight advantage in edge retention compared to S30V.
20CV is an exceptionally wear-resistant steel, with the high volume of vanadium carbides providing superior edge retention.
In CATRA edge retention testing, which measures the number of silica-impregnated cards a blade can cut, 20CV showed 180% of the performance of the 440C reference steel.
While S30V also exhibits excellent edge retention and wear resistance, it falls just short of the performance of 20CV in CATRA testing, achieving 145% of the 440C reference.
S30V edge retention is still better than many other stainless steel like XHP, but trails the very top performers like ZDP-189, S90V, and the M390/20CV family.
Ease of Sharpening
20CV and S30V present challenges when it comes to sharpening and grinding due to their high-hardness, high-carbide content microstructures.
However, CPM S30V knife steel is generally more grindable and sharpenable than CPM 20CV steel.
20CV data sheet notes that the 20CV is only 35-40% of a 1% carbon steel, indicating that it is quite difficult to machine and grind compared to more common tool steels.
This is attributed to the high volume of extremely hard vanadium carbides dispersed throughout the 20CV matrix.
While S30V also contains a significant amount of vanadium carbides to provide wear resistance, the overall carbide content is lower than that of 20CV.
In the annealed condition, S30V is much easier to machine than CPM S90V and is comparable to that of D2.
Corrosion Resistance
20CV and S30V are stainless steels, however, 20CV exhibits better corrosion resistance compared to S30V, primarily due to its higher chromium content.
20CV data sheet indicates that the steel contains the highest amount of chromium, 20%, of any high-vanadium stainless steel.
In contrast, S30V contains a lower chromium content of 14%, which, while still providing good corrosion resistance, is not quite at the same level as the 20CV.
The chromium-rich matrix of 20CV helps protect the blade from pitting, staining, and other forms of corrosive attack.
However, for many general-use applications, the corrosion resistance of S30V is still more than adequate.
Final Thoughts on 20CV vs S30V Steel
20CV, with its exceptional wear resistance and edge retention, is an excellent choice for users who demand the absolute maximum in edge holding performance.
20CV high volume of vanadium carbides gives it the ability to maintain a razor-sharp edge, even in the most demanding environments.
In contrast, S30V strikes a more balanced approach, prioritizing a combination of toughness, corrosion resistance, and good-but-not-extreme wear resistance.
This makes S30V a highly versatile blade steel, well-suited for everyday carry knives, outdoor tools, and general-purpose applications where a combination of properties is valued.
From my own experience with both 20CV and S30V, 20CV has provided exceptional edge retention in my hard-use knives.
While S30V has offered a winning blend of edge retention, corrosion resistance, and ease of maintenance.