CPM CruWear vs S30V Steel

In this article “CPM CruWear vs S30V Steel”, I will compare these two knife steels produced by Crucible Industries using their CPM (Crucible Particle Metallurgy) process. 

It’s important to note that conventional Cru-Wear steel and CPM Cru-Wear steel have differences in properties and how they are produced, so we will focus specifically on the powder metallurgy variant of Cru-Wear i.e. CPM CruWear. 

S30V and CPM Cru-Wear are both popular blade steels used by most knife makers.

However, they have key differences when it comes to toughness, edge retention, sharpenability, and corrosion resistance.

Here are some key takeaways I will cover:

• S30V achieves higher hardness and better edge retention compared to Cru-Wear
• Cru-Wear achieves greater toughness and impact strength over S30V
• Cru-Wear has better ease of sharpening than S30V
• S30V provides better corrosion resistance than Cru-Wear

CPM CruWear vs S30V At A Glance

Hardness

CPM S30V and CPM Cru-Wear are both air-hardening tool steels that can achieve high Rockwell hardness levels, making them suitable for wear-resistant applications like knives, cutting tools and dies. However, S30V generally achieves slightly higher hardness than Cru-Wear.

S30V can be hardened to around 60-64 HRC through a proper heat treatment. It reaches peak hardness when austenitized between 1900-2000°F and double tempered between 400-750°F. 

In contrast, Cru-Wear can be hardened to around 60-65 HRC when austenitized between 1850-2050°F and triple tempered between 900-1050°F. 

While their peak hardness levels are similar, S30V more readily achieves a hardness of 62-64 HRC, while Cru-Wear is typically tempered down to 60-62 HRC for the best combination of wear resistance and toughness.

The higher vanadium content in S30V (4%) compared to Cru-Wear (2.4%) enables more vanadium carbides to form, which improves wear resistance.

S30V also has a higher volume of total carbides (14.5%) versus Cru-Wear (10%), further enhancing its hardness capabilities.

However, Cru-Wear compensates with higher attainable hardness from its secondary hardening response.

S30V reaches slightly higher hardness levels more easily, giving it an edge for better wear resistance, while Cru-Wear offers a better balance of hardness and toughness.

Toughness

While both S30V and CruWear steels prioritize high hardness and wear resistance, Cru-Wear demonstrates substantially greater toughness and impact strength.

Crucible Industries reports the transverse Charpy impact energy of S30V as 10 ft-lbs. In comparison, Cru-Wear exhibits Charpy impact energies between 27-165 ft-lbs depending on the heat treatment.

The much higher toughness of Cru-Wear is enabled by its lower hardening temperature, which results in a finer prior austenite grain size.

Cru-Wear is typically hardened between 1850-2050°F before tempering, while S30V requires 1900-2000°F for hardening.

The data shows austenitizing Cru-Wear at just 1750°F can achieve a remarkable toughness of 165 ft-lbs, over 15 times greater than S30V. However, this comes at the expense of lower hardness around 57 HRC.

Additionally, the high vanadium content of S30V causes more formation of brittle vanadium carbides, reducing steel toughness, thus making this knife steel prone to chipping.

Cru-Wear has lower vanadium as well as molybdenum and tungsten additions to balance wear resistance and toughness.

While S30V is harder and more wear-resistant, Cru-Wear steel demonstrates superior fracture toughness and impact strength due to its more optimized composition and heat treatment parameters. 

This gives Cru-Wear an advantage in applications where shock loads or impact forces are encountered when using the knife.

Edge Retention

S30V has better edge retention and wear resistance compared to Cru-Wear steel. In CATRA (Cutlery and Allied Trades Research Association) edge retention testing, S30V achieved a relative score of about 10% to 15% better edge retention compared to Cru-Wear steel.

The high vanadium content of S30V promotes the formation of hard vanadium carbides, which are more effective than chromium carbides at providing edge retention and wear resistance. 

S30V contains 4% vanadium and 10.5% chromium carbides, totaling 14.5% carbides. In comparison, Cru-Wear has only 2.4% vanadium and 7.5% chromium, totaling 10% carbides.

The higher volume of harder vanadium-rich carbides gives S30V a better ability to hold an edge for long and resist abrasive wear.

Additionally, S30V reaches slightly higher hardness (62-64 HRC) than Cru-Wear (60-62 HRC) in optimal heat treatment. This further improves its edge retention capabilities. 

S30V’s hardness advantage and higher volume of wear-resistant carbides enable it to outperform Cru-Wear in terms of edge retention and abrasion resistance. 

Corrosion Resistance

CPM S30V is stainless steel while CPM-CruWear steel is non-stainless steel, thus S30V provides better corrosion resistance compared to CPM CruWear Steel.

The higher 14% chromium content of S30V promotes the formation of a protective chromium oxide passive film, enhancing corrosion resistance.

S30V also has 2% molybdenum, which further improves corrosion resistance, whereas Cru-Wear does not contain molybdenum and has about 7.5% Chromium content.

Both S30V and Cru-Wear have sufficient corrosion resistance for most applications, S30V’s higher chromium and molybdenum content gives it an advantage in terms of pitting and general corrosion resistance.

Ease of Sharpening

The high hardness and high volume of carbides in S30V and Cru-Wear steels make them more difficult to sharpen and grind compared to lower alloy carbon steels. 

However, Cru-Wear blade steel is easier to sharpen and has better grind ability compared to S30V blade steel.

The higher vanadium carbide content of S30V creates a very abrasion-resistant microstructure, which increases resistance to grinding and sharpening.

Cru-Wear’s lower carbide volume provides better grindability, Cru-Wear is also easier to sharpen and grind due to its slightly lower hardness (60-62 HRC) than S30V (62-64 HRC). 

The highest hardness for S30V comes from large volumes of vanadium carbides, which have a hardness of up to 3200 Vickers, making S30V more difficult to sharpen. Cru-Wear’s lower carbide content gives it better sharpenability.

Overall, while both steels present challenges for grinding and sharpening compared to lower alloy steels, Cru-Wear’s lower carbide content enables somewhat easier grinding, machining, and sharpening.

Final Thoughts on CruWear vs S30V

Having Spyderco knives made from both S30V and Cru-Wear steels, I find each knife steel provides advantages for different applications. 

For me, the Cru-Wear blade’s superior fracture toughness and impact strength enable it to withstand heavy shock loads and impact forces without chipping or breaking.

I can confidently, chop, and lever cans with my Cru-Wear knife without worrying about damage. In contrast, my S30V knife, while harder and more wear-resistant, is prone to chipping if I use it for heavy-duty tasks. 

However, I appreciate S30V’s better corrosion resistance for humid outdoor environments and I recommend it for an EDC as it maintains its edge retention longer. 

The higher chromium and molybdenum content protects against pitting and rust, allowing me to use my S30V knife in wet conditions with confidence. 

Overall, I find Cru-Wear to be the tougher, more abuse-resistant steel, and easy to sharpen while S30V gives me better corrosion resistance and edge retention.