S90V and S30V are two premium blade steels developed by Crucible Industries, a leading manufacturer of specialty steels, including powder metallurgy (CPM) stainless steels.
CPM S90V, previously called CPM 420V, is a highly wear-resistant martensitic stainless steel designed with a high volume of hard vanadium carbides resulting in exceptional edge retention capabilities.
On the other hand, CPM S30V, introduced later in 2001, was specifically engineered as a balanced knife steel, offering a combination of good toughness, corrosion resistance, and edge retention.
With a lower vanadium content of 4% and the addition of molybdenum and nitrogen, S30V strikes a balance between wear resistance and improved grindability compared to its predecessor, S90V.
This balance made S30V a popular choice among knifemakers and paved the way for further developments, such as S35VN and the more recent S45V.
S30V vs S90V Steel At A Glance
| Property | S30V Steel | S90V Steel |
|---|---|---|
| Hardness (HRC) | 58-61 | 56-59 |
| Toughness | Slightly better than S90V in Charpy Impact test | Lower than S30V in Charpy Impact test |
| Edge Retention (CATRA) | Very Good Edge retention | Significantly Better than S30V steel |
| Corrosion Resistance | Slightly Better than S90V | Similar to 440C, slightly lower than S30V |
| Grindability | Easier than S90V comparable to D2 | More difficult due to high wear resistance |
| Wear Resistance | Very good | Excellent, highest of stainless steels |
Hardness
Crucible datasheets indicate that the aim hardness for S90V steel is typically in the range of 56-59 HRC, while the aim hardness for S30V steel is 58-61 HRC.
However, S90V and S30V have the potential to reach higher maximum hardness levels, with the datasheets showing as-quenched hardness values up to 64 HRC.
Higher hardness in knife steels generally leads to better edge retention and slicing performance, but can also make the steel more difficult to sharpen and potentially more prone to chipping or rolling of the edge.
Toughness
Toughness is the ability of a knife to resist chipping and cracking under impact, S30V steel exhibits higher toughness than S90V steel.
In a Longitudinal Charpy C-notch Toughness Testing, S30V achieves around 19 ft-lbs of Toughness, while S90V has lower toughness values around 17 ft-lbs.
The higher toughness of S30V can be attributed to its lower overall carbide content, as well as its lower vanadium content (4% in S30V vs 9% in S90V).
Vanadium carbides are excellent in wear resistance and edge retention but are brittle and detrimental to the toughness of a knife steel.
In knives, the higher toughness of S30V translates to better resistance to chipping and breaking, especially in situations where the blade may encounter side loading or impact forces.
S90V steel lower toughness, while still acceptable for many applications, means it may be more prone to chipping or cracking under extreme impact loads.
Edge Retention
S90V steel achieves significantly higher edge retention compared to S30V steel.
The CATRA (Cutlery & Allied Trades Research Association) testing results show that S90V has 195% better edge retention relative to 440C stainless steel, while S30V achieves 145% relative to 440C.
This superior edge retention of S90V can be attributed to its higher vanadium content 9% vs 4% in S30V, which promotes the formation of a higher volume of hard vanadium carbides.
These vanadium carbides are harder and more effective at providing wear resistance compared to chromium carbides found in other steels.
S90V steel exceptional edge retention for knives translates to blades that can maintain their sharpness for longer periods of use and require less frequent sharpening.
This makes S90V an excellent choice for knives intended for heavy-duty or extended use, such as outdoor and survival knives, where maintaining a keen edge is crucial.
Corrosion Resistance
S90V and S30V steels exhibit comparable levels of corrosion resistance, making it difficult to declare a clear winner in terms of their performance in daily tasks or typical knife applications.
However, datasheets indicate that S30V achieves slightly better corrosion resistance than S90V in polarization curve testing in a 5% sodium chloride solution.
However, the difference in their corrosion resistance is not substantial. S90V’s corrosion resistance is rated as equal to or better than 440C stainless steel.
While S30V steel corrosion testing shows it exceeds 440C steel corrosion resistance by a small margin.
Ease of sharpening
According to the information, S30V steel exhibits better grindability and ease of sharpening than S90V steel.
The S30V datasheet states, “In the annealed condition, CPM S30V is much easier to machine than CPM S90V and is comparable to that of D2.”
The better grindability of S30V can be attributed to its lower overall carbide content, particularly the lower volume fraction of extremely hard vanadium carbides compared to S90V.
For knives, the better grindability of S30V translates to easier sharpening and maintenance of the cutting edge.
Knifemakers and users will find it more convenient to resharpen S30V blades using standard abrasives and sharpening equipment.
In contrast, the high volume of hard vanadium carbides in S90V makes it more challenging to grind and sharpen, often requiring diamond or cubic boron nitride (CBN) abrasives for effective material removal.
While S90V’s high wear resistance provides exceptional edge retention, its poor grindability may be a trade-off for some knife applications.
Final Thoughts on S30V vs S90V
S90V truly stands out for its exceptional edge retention and high wear resistance, courtesy of its substantial 9% vanadium content promoting hard vanadium carbide formation.
S90V steel delivers wicked edge-holding capabilities that are unmatched by most other stainless knife steels.
However, this same attribute also makes S90V incredibly challenging to sharpen and grind, often requiring specialized diamond or CBN abrasives.
On the other hand, S30V, with its well-balanced 4% vanadium content and nitrogen addition, offers a significant improvement in overall performance compared to its predecessors.
S30V provides better edge retention than many other stainless steels while maintaining good toughness, corrosion resistance, and, most importantly, easier sharpening characteristics.
For the average knife user, I would certainly recommend S30V as the more versatile and user-friendly option.
S30V balanced properties make it suitable for a wide range of applications, and its reasonable edge retention and ease of sharpening make it a joy to maintain.
However, if you are an experienced knifemaker or user who prioritizes absolute maximum edge retention and is willing to put in the extra effort required for sharpening, S90V could be an excellent choice.
Its high wear resistance and cutting performance are truly impressive, but it is not a beginner-friendly steel due to its challenging grindability.