CTS 204P vs MagnaCut Steel

MagnaCut is a new powder metallurgy knife steel developed by Dr Larrin Thomas in collaboration with Crucible Industries. 

Unlike traditional stainless steels like CTS 204P from Carpenter Technology, which often contain chromium carbides that can compromise toughness and corrosion resistance.

MagnaCut eliminates these chromium carbides through a unique composition balance of carbon, chromium, vanadium, niobium, and nitrogen.

This innovative approach provides MagnaCut blade steel with better corrosion resistance than many other high-alloy stainless steels, such as CTS 204P.

MagnaCut’s design also enables it to achieve higher toughness levels comparable to non-stainless powder metallurgy steels like CPM-4V while maintaining excellent wear resistance. 

CTS 204P vs MagnaCut Steel At A Glance

Hardness

CTS 204P and CPM MagnaCut are two high-performance powder metallurgy steels.

When it comes to hardness, MagnaCut demonstrates a higher potential for hardness than CTS 204P. 

The CTS 204P datasheets indicate that it typically achieves a working hardness of around 59 HRC, potentially reaching a higher hardness of 62-63 HRC, sacrificing some toughness and corrosion resistance.

On the other hand, MagnaCut can achieve high hardness levels of up to 63 HRC without cold treatment and over 64 HRC with a cryogenic treatment, even reaching 65 HRC in some heat treatments.

This higher achievable hardness in MagnaCut translates to improved wear resistance and edge retention for knives made from this steel while maintaining excellent toughness and corrosion resistance.

However, it’s worth noting that the higher hardness levels may come at the expense of slightly reduced grindability and finishability compared to lower hardness levels.

Edge Retention

CTS 204P steel exhibits better edge retention and wear resistance than CPM MagnaCut steel, an essential consideration for knives requiring excellent edge-holding capabilities.

Based on the CATRA testing data, CTS 204P (or the comparable M390 steel) exhibits better edge retention than MagnaCut. 

The CATRA test, which measures relative wear resistance, showed that M390 at 61.5 HRC scored 180% compared to 440C stainless steel, while MagnaCut at 62.5 HRC scored 135%. 

This indicates that M390/CTS 204P steel has a clear advantage in terms of pure edge retention capability.

CTS 204P datasheet highlights its significant volume fraction of hard vanadium-rich carbides, contributing to its exceptionally high wear resistance. 

MagnaCut steel was designed to have wear resistance and edge retention similar to non-stainless steels like CPM-4V and CPM-CruWear,  but it does not match the edge retention capabilities of CTS 204P or M390 steel.

Knives made from CTS 204P knife steel require less frequent sharpening than those made from CPM MagnaCut steel when used in similar conditions.

Toughness

MagnaCut steel exhibits superior toughness compared to CTS 204P steel, which is a significant advantage for knives made from MagnaCut.

The elimination of chromium carbides and the presence of fine vanadium and niobium carbides in MagnaCut contribute to its excellent toughness.

The micrographs show that MagnaCut has a much finer carbide structure than CTS 204P, which translates to improved toughness and resistance to chipping or breaking.

MagnaCut steel matches or even exceeds the toughness of highly regarded non-stainless powder metallurgy steels like CPM-4V and Vanadis 4 Extra, which are known for their exceptional toughness. 

According to Crucible data, MagnaCut exhibited a toughness of 38 ft-lbs at 62.5HRC in a Longitudinal Charpy C-Notch test.

In contrast, toughness testing shows that 204P / M390 / 20CV measured only 15 ft-lbs at a lower hardness of 62 HRC.

For knives, the superior toughness of MagnaCut allows for the use of thinner edges at more acute angles, improving cutting ability and edge retention while reducing the risk of chipping.

Knifemakers who have worked with MagnaCut have reported excellent toughness during rigorous cutting tests, chopping, and batoning, with minimal edge damage compared to other steels.

In contrast, the coarser carbide structure and potentially lower toughness of CTS 204P blade steel may limit the ability to push edge geometry to its limits without compromising edge integrity.

Corrosion Resistance

MagnaCut and CTS 204P are stainless steels; however, MagnaCut exhibits significantly better corrosion resistance than CTS-204P steel.

Eliminating chromium carbides in the microstructure of MagnaCut steel is a crucial factor contributing to its excellent corrosion resistance.

The absence of chromium carbides prevents the formation of chromium-depleted regions surrounding the carbides, which are typically more susceptible to corrosion.

This design approach and the MagnaCut knife steel’s higher chromium content in solution result in corrosion resistance that surpasses CTS 204P / 20CV /  M390 high-performance stainless steels.

In salt spray corrosion resistance testing, MagnaCut showed no signs of corrosion after 72 hours, while 20CV, similar to CTS 204P steel, exhibited some small corrosion spots.

Spyderco elite Salt Series knives now feature MagnaCut steel, offering superior edge retention despite slightly lower corrosion resistance than LC200N.

Ease of sharpening

MagnaCut grinds and finishes easier than CTS 204P and other high-alloy stainless steels like S30V thanks to its fine microstructure. 

However, MagnaCut becomes slightly more challenging to finish around 240 grit due to the presence of hard vanadium carbides.

Knifemakers have found that MagnaCut sharpens relatively easily, with some reporting better sharpening than CPM-154 and even easier than CPM-4V.

It is capable of taking a very sharp edge, and the burr removal during sharpening is reported to be relatively easy.

It is worth noting that both of these knife steels contain hard vanadium carbides, so sharpening may not be easy for a beginner, they require the right tools and patience to get a good edge.

Final Thoughts on CTS 204P vs MagnaCut Steel

Working with both CTS 204P over the years, I can confidently say that MagnaCut has become my go-to choice for the past year due to its incredible balance of properties.

I like MagnaCut steel, particularly due to its impressive combination of toughness and edge retention, I have not experienced edge rolling on this knife steel for normal use.

While I had previously used CTS 204P for quite a while, and it is undoubtedly an excellent steel, MagnaCut has surpassed it in my preference.

CTS 204P stainless steel equivalent to 20CV or M390, excels in edge retention, outperforming MagnaCut stainless steel.

However, this exceptional wear resistance comes at the expense of reduced toughness and slightly more challenging sharpening characteristics.

In contrast, MagnaCut’s alloy design, which eliminates chromium carbides, not only enhances its toughness to levels comparable to non-stainless powder metallurgy steels but also improves its corrosion resistance and ease of sharpening.

Ultimately, CTS 204P, 20CV, and M390 are formidable steels in their own right, offering outstanding edge retention.

MagnaCut’s unique balance of properties, combining excellent toughness, corrosion resistance, and a highly practical level of edge retention, has made it my preferred choice for the past year.