Bohler M398 Steel better than M390 Steel?

m398 steel knife

What is Bohler M398 Steel?

Bohler M398 steel is a high Chromium martensitic steel produced following the Powder Metallurgy process by Bohler. It is an improvement of M390 steel and was introduced in the market in 2019. M398 steel contains more carbon and vanadium making it very hard steel.

Bohler M398 steel has about 0.8% more carbon elements in its alloy and about 3.2% more Vanadium elements. The addition of these two increases the macro hardness by significantly increasing the carbide volume.

Because of its chemical composition, it offers excellent wear resistance and corrosion resistance, making it suitable for making wear-resistant tools. It is used to make knives, medical equipment, food processing tools, screws, and drilling tools, to mention a few.

Bohler M398 is stainless steel because it meets the 12 percent chromium content requirements to make steel stainless. With a composition of 20% chromium, it offers excellent corrosion resistance properties.

M398 Steel Composition

  • Carbon C 2.70%: Increases the edge retention, hardness and tensile strength. It also improves steel resistance to wear, abrasion and corrosion.
  • Chromium Cr 20.00%: Formation of Chromium carbides Increases hardness, tensile strength and toughness of the blade.
  • Manganese Mn 0.50%: improves the strength and hardness of steel. When the steel is heat-treated, hardenability is improved with increased manganese.
  • Molybdenum Mo 1.00%: It improves machinability and hardness.
  • Vanadium V 7.20%: Increase wear resistance and toughness, it also improves corrosion resistance. High vanadium content enables formation of Vanadium Carbides.
  • Silicon Si 0.50%: Improves grain structure for better hardness, however like Manganese it can increase brittleness.
  • Tungsten W 0.70% Improves wear resistance and hardness, mostly added to tool steel

Properties of M398 steel

Bohler M398 Steel Hardness

Bohler M398 steel has a high hardness of 62-65 HRC, associated with the high amounts of carbon and vanadium in its composition. This high hardness offers great wear resistance, edge retention but sacrifices the toughness.

Bohler M398 Steel Wear resistance

M398 steel passes with flying colors when it comes to wear resistance. Wear and tear from daily use and abrasion have nothing on this steel.  If you are on the market searching for a knife that will serve you for a long time without losing shape, look into the varieties of M398 knives.

The exceptional wear resistance is brought about by the additional carbide volume in its composition from the super tough vanadium carbides.

Bohler M398 Steel Edge Retention

M398 is an improvement of M390, which is known to offer excellent edge retention. With increased carbon and vanadium in its composition, M398 retains a sharp edge for a very long time.

The edge retention of M398 knives contributes to their long lifespan because the blade is not sharpened frequently; hence it does not wear out faster.

Bohler M398 Steel Corrosion Resistance

The amount of Chromium in steel determines its corrosion resistance capabilities. As already stated, M398 contains 20% chromium, which contributes to excellent corrosion resistance. For this reason, M398 steel is a suitable material for making knives to be used in highly corrosive and humid environments.

M398 knives are highly resistant to corrosion, but you should invest in maintenance. Please do not leave the blades in water for a long time and wash and dry them after use to increase their lifespan.

Bohler M398 Steel Toughness

As a rule of thumb, hard steel does not offer good toughness. Being very hard steel, the toughness of M398 suffers. However, this is not to say that it has the poorest toughness out there.

It offers decent toughness to prevent its blades from chipping and breaking easily when exposed to pressure and tough applications. However, be careful not to use knives made from this steel on very tough applications like batoning. It will be like setting them up for failure.

Ease of sharpening Bohler M398 Steel

The hardness and wear resistance of steel determines how easy it will be to sharpen. With high hardness and excellent wear resistance, we expect M398 to be challenging to sharpen, which is true. It sacrifices sharpness over hardness and high wear resistance.  

M398 Steel Comparison

M398 vs. M390

Bohler M398 is an improvement of M390; therefore, we expect it to offer better performance. It contains more Carbon and Vanadium hence offering higher hardness with better wear resistance and edge retention. M398 steel has about 0.8% more carbon elements in its alloy and about 3.2% more Vanadium elements. The addition of these two increases the macro hardness by significantly increasing the carbide volume.

According to Bohler, M398 steel has an excess of 30% carbide volume compared to the already outstanding M390 steel. The higher amount of carbides makes it extremely hard but reduces the toughness of M398 over M390 steel.

They contain the same amount of Chromium hence offer almost the same level of corrosion resistance. Sharpening Bohler M390 steel is easier due to the relatively low carbide volume compared to M398 steel.

M398 Steel vs. D2 steel

M398 offers better performance because it has higher hardness, better edge retention, wear resistance, and toughness. Also, M398 provides better corrosion resistance because it is stainless steel, while D2 is semi-stainless. On the other hand, sharpening D2 is easier. D2 steel is old steel and can’t be compared in performance to the new powder metallurgy steel.

See Also: CPM MagnaCut Steel, new steel with great edge retention and toughness.

Is M398 good knife steel?

Bohler M398 steel is a good steel for a knife because it offers excellent edge retention, great wear resistance, outstanding corrosion resistance, and decent toughness. On the downside, it is not easy to sharpen, and it is expensive.

In my opinion, I do not see a need of getting this steel over M390 as the improvement is very minimal and it sacrifices user-friendliness in terms of ease of sharpening and toughness.

I would prefer steel that cuts across in terms of edge retention, ease of sharpening, and toughness. Most high-end and mid-range steels (S35VN, N690, and 14C28N) would provide these features without necessarily being as expensive as M398 steel.

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