M390 vs. S30V

M390 and S30V are two of the most popular high-performance steels used in premium knives today. Both are known for their excellent balance of edge retention, toughness, and corrosion resistance, but they cater to different user needs and preferences.

M390, produced by Bohler-Uddeholm, is a powder metallurgy steel known for its extreme wear resistance and corrosion resistance, making it a top choice for high-end knives. On the other hand, S30V, developed by Crucible Industries, was one of the first steels specifically designed for knives and remains a popular option due to its balance of edge retention and ease of sharpening.

This article will provide a detailed comparison between M390 and S30V based on scientific data and measurable properties. We will examine their chemical composition, performance metrics (edge retention, toughness, corrosion resistance), manufacturing processes, heat treatment requirements, and real-world performance characteristics.

By the end of this article, you will have a clear understanding of which steel is best suited for your needs.

Composition Analysis

The chemical composition of a steel determines its fundamental properties such as hardness, toughness, wear resistance, and corrosion resistance. Below is a comparison of the chemical makeup of M390 and S30V:

Element	M390	S30V
Carbon (C)	1.90%	1.45%
Chromium (Cr)	20.00%	14.00%
Vanadium (V)	4.00%	4.00%
Molybdenum (Mo)	1.00%	2.00%
Tungsten (W)	0.60%	–
Silicon (Si)	0.70%	0.50%

Key Differences in Composition:

M390 has a higher chromium content at 20%, which significantly enhances its corrosion resistance compared to S30V’s 14% chromium.
Carbon content is also higher in M390 (1.90%) than in S30V (1.45%), contributing to its superior hardness and edge retention.
Both steels contain 4% vanadium, which forms hard vanadium carbides that improve wear resistance.
The presence of tungsten in M390 further increases its hardness and wear resistance.

Performance Metrics

Edge Retention (CATRA Test Results)

Edge retention is one of the most critical factors for knife users who need their blades to stay sharp over extended periods of use. The CATRA (Cutlery & Allied Trades Research Association) test measures how much material a blade can cut before it dulls.

M390: In CATRA tests, M390 consistently outperforms S30V due to its higher carbide volume and superior wear resistance. M390 typically achieves around 542 mm in standardized cutting tests[4].
S30V: S30V, while still excellent in edge retention compared to many other steels, cuts approximately 481 mm, making it slightly less durable than M390[4].

Toughness

Toughness refers to a steel’s ability to resist chipping or cracking under impact or stress.

M390: Despite its high hardness, M390 offers moderate toughness due to its fine grain structure from powder metallurgy processes. However, it is not as tough as lower-hardness steels.
S30V: S30V provides better toughness than M390 due to its lower carbon content and optimized balance between hardness and toughness[1].

Corrosion Resistance

Corrosion resistance is essential for knives used in humid or salty environments.

M390: With its high chromium content (20%), M390 offers superior corrosion resistance compared to most knife steels[2]. It performs exceptionally well in saltwater environments.
S30V: While still highly resistant to corrosion with 14% chromium, S30V does not quite match the performance of M390 in extreme conditions[5].

Hardness Range

Hardness is measured on the Rockwell C scale (HRC), indicating how hard the steel is after heat treatment.

M390: Typically hardened to between 60-62 HRC, providing excellent edge retention at the expense of some toughness[2].
S30V: Generally hardened to around 58-61 HRC, offering a good balance between hardness for edge retention and toughness for impact resistance[7].

Heat Treatment Considerations

Heat treatment plays a crucial role in optimizing the performance characteristics of both M390 and S30V.

M390 Heat Treatment

M390 requires precise control during heat treatment due to its complex composition:

Optimal hardening temperature: Between 1050°C – 1100°C.
Quenching: Rapid cooling is necessary to prevent carbide segregation.
Tempering: Usually performed at around 500°C – 550°C to achieve optimal hardness without sacrificing too much toughness[2].

S30V Heat Treatment

S30V is somewhat easier to heat treat:

Optimal hardening temperature: Around 1065°C – 1080°C.
Quenching: Requires controlled cooling but is less sensitive than M390.
Tempering: Typically done at temperatures between 500°C – 550°C, similar to M390 but with more flexibility in achieving desired properties[6].

Real-World Performance Characteristics

Edge Stability

Edge stability refers to how well the knife maintains its sharpness without chipping or rolling during use.

M390: Thanks to its high carbide volume and fine grain structure, M390 excels in maintaining edge stability even under heavy use[8].
S30V: While still stable, S30V’s softer nature compared to M390 means it may experience more micro-chipping under extreme stress[5].

Sharpening Behavior

Sharpening difficulty can be an important consideration for users who frequently maintain their knives.

M390: Due to its extreme hardness and wear resistance, sharpening M390 can be challenging and time-consuming[2].
S30V: Easier to sharpen than M390 due to its slightly lower hardness and simpler carbide structure[7].

Wear Patterns

Wear patterns refer to how evenly the blade wears down over time.

M390: Exhibits very slow wear thanks to its high vanadium carbide content but can develop micro-chips if used improperly on hard materials[8].
S30V: Wears more evenly but at a faster rate than M390 due to lower overall hardness[5].

Conclusion

In conclusion, both M390 and S30V are excellent steels with distinct advantages depending on the intended use:

If you prioritize extreme edge retention and corrosion resistance for tasks like outdoor survival or professional culinary work where long-lasting sharpness is crucial, then M390 is your best option.
For users who need a more balanced steel that offers good edge retention with easier sharpening and better toughness for everyday carry or tactical applications, then consider choosing knives made from S30V.

Both steels represent the pinnacle of modern metallurgy but cater to slightly different user preferences based on their unique compositions and performance metrics.

FAQ

What makes M390 harder to sharpen than S30V?

The higher carbide volume in M390 increases wear resistance but also makes it more difficult to sharpen compared to S30V.

Which steel has better corrosion resistance?

M390 has superior corrosion resistance due to its higher chromium content (20%) compared to S30V’s 14%.

Is there a significant cost difference between knives made from these steels?

Yes, knives made from M390 are generally more expensive due to the complex powder metallurgy process involved in manufacturing it.

Can I use both steels for outdoor or tactical purposes?

Yes! Both are suitable for outdoor use; however, if you need higher toughness for impact-heavy tasks like batoning wood, S30V may be preferable.

Citations:
[1] https://damascussteelbillets.com/m390-vs-s35vn/
[2] https://nobliecustomknives.com/m390-steel/
[3] https://forum.spyderco.com/viewtopic.php?t=94034
[4] https://knifesteelnerds.com/2019/10/07/catra-tests-of-m390-knives/
[5] https://www.reddit.com/r/Blades/comments/26faz2/m390_blade_steel_vs_s30v_and_154cm/
[6] https://www.shieldon.net/s35vn-vs-m390-steel-which-one-is-better/
[7] https://knifeinformer.com/discovering-the-best-knife-steel/
[8] https://nobliecustomknives.com/elmax-steel/