CPM S45VN and CPM 154 are produced by Crucible Industries using powder metallurgy, providing fine and consistent carbide structures.
S45VN contains higher amounts of vanadium and chromium compared to CPM 154, giving it better edge retention, and corrosion resistance.
CPM 154 is the powder metallurgy version of 154CM stainless steel. It has lower carbon and higher chromium compared to 154CM which improves its toughness and corrosion resistance.
While S45VN favors wear resistance and CPM 154 leans towards toughness and ease of sharpening.
CPM 154 vs S45VN Steel At A Glance
| Property | CPM 154 Steel | S45VN Steel |
|---|---|---|
| Hardness | 55-61 HRC | 59-61 HRC |
| Toughness | Higher (12-13 ft-lbs) | Lower (10.5-11 ft-lbs) |
| Edge Retention | Lower (120% of 440C) | Higher (143% of 440C) |
| Corrosion Resistance | Good | Better |
| Ease of Sharpening | Better | Moderate |
| Carbide Content | Lower (~15%) | Higher (17-20%) |
Hardness
The hardness of knife steel determines its resistance to wear, abrasion, and deformation during use.
CPM 154 Steel has a wider range of achievable hardness at 55-61HRC compared to CPM S45VN with a range of 59-61 HRC.
Testing shows that with proper heat treatment, S45VN and CPM 154 can both achieve very high hardness around 63 HRC.
The high hardness capabilities of these steels allow knives made from them to better retain a sharp edge. They are also more resistant to scratches, dents, and scuffs during rigorous use.
Knives made from S45VN or CPM 154 knife steel will have excellent edge retention and wear very well.
CPM 154 steel hardness will however be more suitable for a variety of knives that require different hardness.
Toughness
CPM 154 exhibits moderately higher toughness compared to S45VN, with an advantage of about 15%, when properly heat treated.
With optimized heat treatments, CPM-154 reached approximately 12-13 ft-lbs toughness, while S45VN achieved around 10.5-11 ft-lbs.
The higher toughness in CPM 154 is attributed to its lower overall carbide content compared to S45VN.
Both steels exhibit a peak toughness point depending on heat treatment parameters.
The toughness of both steels can be maximized by selecting the appropriate austenitizing and tempering temperatures.
Edge Retention
Edge retention, or the ability of a knife to resist dulling during use, is an important property for knife steels.
S45VN steel has significantly better edge retention compared to CPM 154 based on its compositions.
S45VN contains higher amounts of vanadium carbides which impart substantial wear resistance.
Testing by Crucible shows S45VN has a CATRA (Cutlery and Allied Trades Research Association) edge retention rating of 143% relative to a 440C baseline, versus 120% for CPM-154.
Independent testing also demonstrates that S45VN has similar or better edge retention compared to S30V and Elmax, which outperform CPM 154.
The higher hardness achievable in S45VN also contributes to improved edge holding.
The superior edge retention of S45VN translates to longer intervals between sharpening, less steel loss during re-profiling, and better retention of sharpness during demanding tasks.
However, CPM 154 compensates with advantages in ease of sharpening and grindability.
Corrosion Resistance
Both S45VN and CPM 154 Steel are stainless steel with high corrosion resistance, however, S45VN exhibits better corrosion resistance than CPM 154 steel.
S45VN steel has a higher chromium content at 16% compared to 14% for CPM 154 steel. However, CPM 154 contains 4% molybdenum while S45VN only has 2%.
Molybdenum improves corrosion resistance, especially in environments containing chlorides.
Experimental corrosion testing in a salt spray showed that S45VN performs similarly to 204P/M390 steels and better than S35VN.
CPM 154 stainless steel has corrosion resistance close to 440C but improved over ATS-34.
Overall, S45VN stainless steel has moderately better corrosion resistance than CPM 154 due to its higher chromium content, despite the lower molybdenum.
The improved corrosion resistance of S45VN will result in better resistance to pitting, staining, and rusting during normal use and cleaning.
Ease of Sharpening
Grindability and sharpenability of knife steels are largely dependent on the type, amount, and hardness of carbides present.
S45VN and CPM 154 contain vanadium and chromium carbides. However, CPM 154 has a lower overall carbide content at around 15% compared to 17-20% for S45VN.
The harder vanadium carbides are more difficult to abrade than chromium carbides. S45VN has a higher proportion of vanadium carbides due to its higher vanadium content.
Micrographs also show that S45VN has slightly larger carbides than CPM 154. Therefore, CPM 154 is generally regarded as having better grindability and sharpenability relative to S45VN.
For knife making, the ease of grinding CPM 154 reduces labor time and cost. It also enables easier re-profiling or sharpening of the edge by the end user.
The grindability difference is not large though, so S45VN is still considered reasonably easy to work with.
But CPM154 steel’s advantage in grindability and sharpenability makes it preferred when ease of finishing is a priority.
The tradeoff is that S45VN offers superior edge retention due to its higher carbide content, so it stays sharp for long than CPM 154 Steel.
Final Thoughts on CPM 154 vs S45VN Steel
In conclusion, S45VN steel achieves higher edge retention compared to CPM 154 steel due to its higher vanadium carbide content.
S45VN stainless steel exhibits better corrosion resistance thanks to increased chromium.
However, CPM 154 maintains a toughness advantage over S45VN along with better grindability and sharpenability.
For most users, I foresee that either steel will perform superbly, with excellent edge retention, corrosion resistance, and toughness.
S45VN is best suited for those who prioritize hardness, wear resistance, and corrosion performance.
CPM 154 steel blend of toughness and grindability makes it a top choice when ease of sharpening and polishing is paramount.