S90V and S45VN are two premium steels produced by Crucible Industries using their powder metallurgy process called CPM (Crucible Particle Metallurgy).
As high-performance stainless steels, they offer exceptional properties like high wear resistance, edge retention, and corrosion resistance desired in knife steels.
The key difference lies in their alloying elements, particularly vanadium content. S90V contains a very high 9% vanadium while S45VN has a more modest 3% vanadium addition.
The higher vanadium carbide volume in S90V gives it unparalleled wear resistance and edge retention compared to S45VN but comes at the cost of more difficult sharpening and somewhat lower toughness.
CPM S45VN is part of Crucible’s S30V family including S30V and S35VN, and aims for better balance between edge retention, corrosion resistance, and ease of sharpening.
S45VN vs S90V Steel At A Glance
| Property | S90V Steel | S45VN Steel |
|---|---|---|
| Alloying Elements | 9% Vanadium, 14% Chromium, 1% Molybdenum, 2.3% Carbon | 3% Vanadium, 16% Chromium, 2% Molybdenum, 0.5% Niobium, 0.15% Nitrogen 1.48% Carbon |
| Hardness (HRC) | Capable of 64+ HRC, typically 56-59 HRC for knives | Capable of 64+ HRC, typically 59-61 HRC for knives |
| Edge Retention | Exceptional better than S45VN | Very good |
| Toughness | Lower than S45VN | Higher than S90V |
| Corrosion Resistance | Excellent, but slightly lower than S45VN | Excellent slightly better |
| Ease of Sharpening | More difficult | Easier than S90V |
Hardness
S90V and S45VN are both capable of achieving high hardness levels, around 64+ HRC given an appropriate heat treatment.
However, S90V appears to achieve slightly higher hardness at peak temperature.
While both steels can reach high hardness levels, the aim hardness for each steel for knife applications is somewhere in the range of lower 56HRC up to 61HRC.
The higher achievable hardness gives S90V an advantage for certain knifemaking applications where maximum wear resistance and edge retention are critical.
Edge Retention
S90V steel achieves higher edge retention compared to S45VN due to its higher volume of vanadium carbides.
S45VN steel achieved a CATRA score of around 143% relative to 440C in edge retention testing.
In comparison, S90V steel offers about 40% better edge retention than S45VN steel.
The higher vanadium content of 9% in S90V versus 3% in S45VN leads to a higher volume fraction of hard vanadium carbides that resist abrasive wear, which gives S90V an advantage in edge retention.
Research indicates both S90V and S45VN perform significantly better in edge retention testing than other stainless steels like S30V, S60V, and S35VN.
The edge retention of S90V is highly comparable to higher carbide stainless steels like S110V and Bohler M398 Steel.
For knives, the ultra-high edge retention of S90V makes it suitable for applications requiring extended periods between sharpening.
Toughness
S45VN achieves higher toughness compared to S90V steel, which is due to differences in alloying elements affecting carbide volume and grain size.
For knife blades, the higher toughness of S45VN makes it more resistant to chipping and catastrophic failure compared to S90V.
S45VN Crucible data sheet shows Charpy impact toughness values around 11-12 ft-lbs for the recommended heat treatment.
In comparison, S90V steel achieved around 8-9 ft-lbs Charpy toughness with the recommended heat treatment.
The higher toughness in S45VN is attributed to its lower overall carbide content of around 15% by volume compared to 20% for S90V.
The lower carbide content is achieved through careful balancing of chromium, vanadium, niobium, and nitrogen.
Additionally, S45VN steel develops a finer carbide grain size than S90V steel.
The lower carbide content and finer grain size reduce brittleness and improve fracture resistance.
S45VN knife steel higher toughness than S90V steel also makes it suitable for larger and bigger blades.
The choice between the two steels depends on the desired balance of wear resistance versus the risk of chipping based on the intended use.
Corrosion Resistance
CPM S90V and S45VN are stainless steels with excellent corrosion resistance.
However, S45VN achieves slightly better corrosion resistance compared to S90V stainless steel due to its higher chromium and molybdenum content.
S45VN contains 16% chromium and 2% molybdenum compared to 14% chromium and 1% molybdenum in S90V.
The higher chromium and molybdenum increase corrosion resistance by improving the stability of the protective passive surface layer.
Additionally, S45VN forms less chromium carbides due to its niobium addition, leaving more chromium dissolved in the steel matrix.
Better corrosion resistance provides an advantage for S45VN knives in applications where moisture and harsh environments are encountered frequently.
Ease of Sharpening
S45VN is easier to sharpen and grind compared to S90V stainless steel. This is attributed primarily to the lower volume fraction of hard vanadium carbides in S45VN.
S90V steel very high 9% vanadium content leads to a high volume of hard vanadium carbides that resist abrasion and wear.
This also makes the steel more difficult to cut and abrade during grinding and sharpening.
In comparison, S45VN contains only 3% vanadium resulting in a lower carbide content.
With its reduced carbide volume, S45VN is noted to sharpen and grind similar to S35VN, which is easier than S30V.
S90V’s grinding characteristics are described as more difficult than S30V due to the higher vanadium carbide content.
The improved ease of sharpening and grinding gives S45VN knives an advantage in terms of manufacture and re-sharpening during use.
S45VN offers a better balance of edge retention and the ability to re-sharpen when needed.
This makes S45VN more suitable for most general-purpose knife uses where periodic sharpening is required.
Final Thoughts on S45VN vs S90V Steel
In conclusion, I believe S90V and S45VN offer an interesting comparison between maximizing edge retention and balancing sharpenability.
For me, S90V’s incredibly high 9% vanadium content provides superior wear resistance and better edge retention than any other stainless steel I have encountered.
However, that vanadium carbide volume comes at the cost of more difficult sharpening.
This makes S90V best for low-maintenance applications where you can go longer between sharpenings.
S45VN with its reduced 3% vanadium strikes a better balance, in my opinion.
The niobium and nitrogen additions help offset the lower vanadium while improving corrosion resistance.
While it doesn’t quite match S90V’s edge retention, S45VN is significantly easier to sharpen and grind.
For most EDC tasks, S45VN’s well-rounded properties make it a better choice over S90V.
At the end of the day, I believe S45VN offers an excellent upgrade over earlier S30V-series steels. But for pure cutting performance, S90V remains hard to beat.