420HC stainless steel, conventionally manufactured by Latrobe, is extensively used in the production of Buck Knives and other outdoor knives.
The “HC” in the designation 420HC stands for “high carbon,” distinguishing it from the more common 420 stainless steel, which contains slightly lower carbon content.
In contrast, CPM S35VN is produced using Crucible Particle Metallurgy (CPM) process, resulting in a highly homogeneous, fine-grained microstructure with unique carbide distributions.
The key differences between these two blade steels lie in their respective trade-offs between hardness, toughness, and corrosion resistance.
CPM S35VN, sacrifices some toughness to attain its better edge retention and abrasion resistance.
Conversely, 420HC offers enhanced impact toughness and corrosion protection, though at the expense of ultimate cutting performance.
420HC vs S35VN Steel At A Glance
| Property | 420HC Steel | CPM S35VN Steel |
|---|---|---|
| Hardness | Upto 55 HRC | 58-61 HRC |
| Toughness | Excellent, ~2x tougher than S35VN | Average toughness |
| Edge Retention/Wear Resistance | Fair wear resistance | better edge retention than 420HC |
| Corrosion Resistance | Excellent, better than S35VN | Lower pitting potential than 420HC |
| Ease of Sharpening | Very easy to sharpen and grind | Harder compared to 420HC |
| Cost | Lower cost due to standard production process | Higher cost due to specialized CPM powder metallurgy process |
Hardness
CPM S35VN is a martensitic stainless steel that can be heat treated to achieve a recommended hardness range of 58-61 HRC, it can however achieve up to 64HRC.
In contrast, 420HC is a martensitic stainless steel that can be hardened to around 55 HRC.
The higher hardness of CPM S35VN compared to other steels like 420HC and 154CM is achieved through the formation of vanadium and niobium carbides, which are more effective at providing wear resistance than standard chromium carbides.
Toughness
420HC steel has a significant advantage in toughness over CPM S35VN steel.
420HC exhibits an impressive level of toughness, with the data indicating it has nearly twice the impact energy of the CPM S35VN in transverse Charpy testing.
The enhanced toughness in 420HC is due to its microstructure, which features smaller carbides and a lower overall carbide volume compared to the more highly alloyed CPM S35VN.
lower carbide allows 420HC to better resist chipping and cracking, making it an excellent choice for larger, heavy-duty knife blades that may encounter impacts or lateral stresses during use.
In contrast, the CPM S35VN sacrifices some of this toughness in exchange for its superior wear resistance and edge retention.
Edge Retention
The edge retention and wear resistance of CPM S35VN steel is significantly superior to that of 420HC stainless steel.
CPM S35VN exhibits 145% of the edge retention compared to the benchmark 440C steel when tested using the CATRA (Cutlery & Allied Trades Research Association) wear test.
This is attributed to S35VN steel unique composition, which includes high levels of vanadium and niobium carbides.
These hard carbides are more effective at providing abrasion resistance than the standard chromium carbides found in conventional 420HC stainless steel.
The superior wear resistance of CPM S35VN translates to knives that can maintain their razor-sharp edges for much longer periods of use, reducing the need for frequent resharpening.
Corrosion Resistance
420HC and S35VN are martensitic stainless steels with very good corrosion resistance, however, 420HC steel exhibits superior corrosion resistance compared to the CPM S35VN steel.
CPM S35VN data sheet corrosion resistance testing results, show that its pitting potential in a 5% sodium chloride solution is lower than that of 420HC and other stainless steels like 440C.
The difference in corrosion performance can be attributed to each steel composition.
420HC contains 13% chromium, which helps provide excellent general corrosion resistance by forming a passive chromium oxide layer.
CPM S35VN, on the other hand, has a higher total alloy content, with 14% chromium as well as additions of vanadium, molybdenum, and niobium.
While these alloying elements enhance S35VN steel wear resistance, they also result in a higher volume of carbides that reduce the amount of chromium available in solid solution to resist corrosion.
The lower carbide content of the 420HC means more of its chromium remains in the matrix, enabling it to outperform the CPM S35VN in terms of corrosion resistance.
This makes 420HC a better choice for knives and tools that will be exposed to humid environments, saltwater, acidic foods, or other corrosive conditions.
Ease of Sharpening
420HC stainless steel exhibits significantly better grindability and ease of sharpening compared to the CPM S35VN steel.
Latrobe 420HC data sheet states that its machinability is rated at 50-55% of a 1% carbon steel, indicating it is relatively easy to machine and grind.
This difference in grindability can be attributed to the steels’ respective hardness levels and carbide structures.
420HC can be heat treated to a hardness of around 55 HRC, which is slightly lower than the 58-64 HRC range mentioned for the CPM S35VN.
Additionally, the 420HC contains a lower volume and smaller size of hard carbides compared to the more highly alloyed CPM S35VN.
The combination of lower hardness and less carbide makes the 420HC much easier to sharpen and grind than the CPM S35VN.
Cost
The cost of knives made with 420HC stainless steel is generally lower compared to those utilizing CPM S35VN steel, due to the differences in their production processes.
420HC is a more conventional martensitic stainless steel produced through standard melting and casting practices.
This relatively straightforward manufacturing method allows 420HC to be more economically sourced and manufactured into knife blades.
In contrast, the CPM S35VN is produced using Crucible’s proprietary Crucible Particle Metallurgy (CPM) process.
The powder metallurgy technique CPM production process also comes at a higher cost compared to standard steel making.
Final Thoughts 420HC vs S35VN Steel
From my own experience, both of these stainless steel options have proven to be excellent knife blade materials, each with its strengths and weaknesses.
For the majority of knife applications, I would urge anyone to select the CPM S35VN as it is a well-balanced all-around performer.
S35VN edge retention and corrosion resistance make it an ideal choice for everyday kitchen, outdoor, and tactical knives where prolonged cutting performance is paramount.
However, for knives that will be subjected to more extreme conditions and abuse, such as outdoor fixed-blade designs intended for tasks like batoning, 420HC steel may be the better option.
420HC significantly higher toughness and superior corrosion resistance, while sacrificing some of the S35VN cutting edge superiority, make 420HC a stellar choice for rugged, high-impact use.
420HC’s combination of excellent impact strength and corrosion protection would be a great match for knives destined to encounter harsh environments and heavy-duty applications.