CPM 154 and 440C are two stainless steels commonly used for knife blades, but CPM 154 generally outperforms 440C for most cutting applications.
CPM 154 is produced using a modern powder metallurgy process while 440C is an ingot-cast old stainless steel.
CPM 154 is the powder metallurgy version of 154CM steel, making it finer-grained and more homogeneous than conventionally processed 154CM.
The powder metallurgy production of CPM 154 results in a fine, homogeneous carbide microstructure compared to the more banded, coarse carbides in 440C and 154CM.
Powder Metallurgy production provides CPM 154 with better toughness, edge retention, wear resistance, grindability, and corrosion resistance than 440C or 154CM.
CPM 154 vs 440C At A Glance
| Property | CPM 154 Steel | 440C Steel |
|---|---|---|
| Production Method | Powder metallurgy | Ingot metallurgy |
| Hardness | 55-62 HRC | 53-60 HRC |
| Toughness | 2 times that of 440C | Lower toughness |
| Edge Retention | Better than 440C steel | Moderate |
| Wear Resistance | Better | Good |
| Corrosion Resistance | Better in most conditions | Moderate |
| Sharpenability | Excellent, easier to sharpen | Good |
Hardness
CPM 154 generally achieves higher hardness values than 440C, with CPM 154 capable of reaching 62 HRC from an oil quench compared to 60 HRC for 440C.
The higher carbon content of 440C enables it to attain slightly higher hardness at 57-60 HRC depending on austenitizing temperature.
However, CPM 154 maintains better toughness at high hardness levels owing to its fine, uniform carbide structure from the powder metallurgy production method.
This gives CPM 154 superior edge retention and resistance to chipping compared to 440C. Testing shows CPM 154 has twice the toughness of 440C at the same hardness.
The more even distribution of harder carbides in CPM 154 also enables better sharpenability.
Toughness
CPM 154 steel demonstrates significantly higher toughness than 440C stainless steel, which provides improved performance in knives.
The fine, uniform carbide distribution and lack of banding in CPM 154 enabled by powder metallurgy production results in a tougher martensitic structure than the ingot-cast 440C steel.
Testing data indicates CPM 154 steel has around twice the toughness of 440C steel at comparable hardness levels.
The higher toughness of CPM 154 is maintained even at high hardness levels of 55-62 HRC. In contrast, the lower toughness of 440C decreases further at high hardness.
For knives, the higher toughness of CPM 154 translates to better resistance to chipping and edge micro-fracturing during cutting and impact.
This gives CPM 154 steel knives enhanced durability over 440C steel knives under hard use.
Additionally, the higher toughness of CPM 154 allows blades to be designed with thinner cross-sections and acuter edges than possible with 440C while retaining strength.
Corrosion Resistance
CPM 154 and 440C are stainless steel, however, CPM 154 exhibits better corrosion resistance than 440C stainless steel in most conditions.
The higher chromium content of CPM 154 at 14% compared to 440C at 17% improves corrosion resistance.
However, the key factor is the added molybdenum in CPM 154 at 4% versus just 0.4% in 440C stainless steel.
Molybdenum significantly enhances pitting and crevice corrosion resistance. Testing data shows CPM 154 resists corrosion better than 440C in salt spray and acid environments.
The improved corrosion resistance allows CPM 154 knives to better withstand discoloration, pitting, and rusting during use and cleaning.
It provides enhanced performance in wet environments and when cutting acidic foods.
The only exception is CPM 154 may undergo slight sensitization during tempering from 700-1000°F which could decrease corrosion resistance.
Edge Retention
CPM 154 steel provides significantly better edge retention and wear resistance than 440C stainless steel for knife applications.
The fine, uniform carbide distribution in CPM 154 from powder metallurgy production results in a harder martensitic matrix compared to the ingot-produced 440C.
Testing data shows CPM 154 has higher hot hardness and achieves a hardness range of 55-62 HRC, while 440C reaches 53-60 HRC depending on austenitizing temperature.
The harder matrix of CPM 154 enables superior wear resistance. Additionally, CPM 154 contains 4% molybdenum versus only 0.4% in 440C, which further improves wear properties.
The combination of higher attainable hardness and more wear-resistant carbides gives CPM 154 better abrasion resistance and ability to retain a sharp cutting edge compared to 440C.
For knives, this translates to CPM 154 maintaining sharpness longer under use and requiring less frequent sharpening than 440C.
The powder-produced microstructure also enables CPM 154 to be sharpened more easily than 440C when required.
Ease of sharpening
CPM 154 steel is significantly easier to sharpen and grind compared to 440C stainless steel.
The fine, homogeneous carbide structure of CPM 154 enabled by powder metallurgy production allows for easier sharpening.
The carbides in 440C are more clustered and coarse than in the conventional ingot metallurgy process. Testing data shows CPM 154 requires nearly 25% less grinding force than 440C.
The ease of sharpening CPM 154 knives allows knives to be brought back to a razor edge quickly with less effort and time. This helps maintain peak cutting performance with regular sharpening.
CPM 154 is also easier to grind into shape during manufacturing, reducing machining costs and effort to create complex blade designs compared to 440C.
The fine carbides in CPM 154 also produce a more uniform, polished finish when ground that enhances aesthetics and corrosion resistance.
Final Thoughts on CPM 154 vs 440C
Overall, the combination of higher attainable hardness along with increased toughness makes CPM 154 generally better than 440C for knives, providing better edge holding, sharpening, and durability.
Having experience with both CPM 154 and 440C steels in knives, I find that CPM 154 is often the better choice for most users.
I consider CPM 154 a well-rounded steel suitable for a wide variety of applications, with a good balance of sharpenability, edge retention, and toughness.
CPM 154 stainless steel offers a combination of properties that make it easy to maintain and use for most people.
On the other hand, 440C stainless steel is a decent classic stainless steel when properly heat-treated.
It provides pretty good edge holding, corrosion resistance, and durability. However, modern steels like CPM 154 now surpass 440C in most aspects.
In my experience, some knifemakers and users still prefer the familiar 440C due to long-term use, while many others favor CPM 154 for its overall performance and value.