Steel M390

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Steel M390

Produced by BÖHLER, the M390 MICROCLEAN is a third generation stainless steel produced with powder metallurgy with extreme wear resistance, high corrosion resistance, high toughness and dimensional stability, excellent flexibility and resistance to mechanical shocks.
M390 (produced by Bohler-Uddeholm) martensitic chrome steel is a third generation PM stainless steel that offers excellent resistance to wear and corrosion thanks to the high content of chromium and vanadium.

The PM process, combined with the high chromium content, gives the M390 good workability and excellent polishability.

The M390 is a fine-grained alloy and is the preferred choice for high-end locks and small fixed blades.
Its high austenization temperature provides the M390 with a high hardness of HRC 58-62.
The ideal hardness is HRC 60/61,recommended for high performance blades. (M390 hardens to 60-62 HRC) and most of the production knives are in the 60-62 HRC range.
The famous Spyderco uses M390 steel on some series.
Steel produced with powder metallurgy with extreme wear resistance, high corrosion resistance, excellent grindability, high polishability, toughness and dimensional stability.

It has excellent edge retention, corrosion resistance and very high hardness for excellent wear resistance.

Chromium, molybdenum, vanadium and tungsten are added to promote sharpness and exceptional edge retention.

The M390 is a fantastic steel and is one of the most commonly used “supersteels” around.

As with any steel, however, it has its advantages and problems.

The M390 is first of all an exceptional steel for wire retention.

You will not see much wear of the thread even through a rather approximate and care less caring use of the blade.

With a higher chromium content, it tends to form slightly larger carbides, what does this translate into? which is harder to get some sort of mind-blowing thread that cuts like a super razor, that rests a hair and splits in two.

As a tip it needs about 15° of lateral inclination as a sharpening angle to get the best performance and tightness of the wire.

By the way forget to sharpen it with a field sharpever, it is annoying to sharpen, since its high wear resistance results in resistance to sharpening stones,especially the highest grain.

The excellent cutting sealing capabilities, maintaining it is very simple, another thing that is worth noting in fact is the absence of resistant burr formations during sharpening; as a result, there is also no risk of forming a false wire.

It also has a rather respectable robustness and can withstand a good blow.

Corrosion? with 20% chromium, it is also very resistant to corrosion!

Unlike other stainless steels, most carbides are made of vanadium and molybdenum, leaving more than chromium free to prevent corrosion.

It can be polished for an extremely high surface finish.

Bohler calls this steel “Microclean” and can be polished to get a real mirror but it is a steel that provides excellent performance with both finishes, rough or very polished.

 

The price?

The price can be a problem, because M390 is significantly more expensive than 154CM and S30V, to understand us about prices:

  • Thickness 3.5X40X300 mm. (€49.00)
  • Thickness 3.5X40X600 mm. (€98.00)
  • Thickness 3.5X40X900 mm. (€147.00)
  • Thickness 3.5X40X1200 mm. (€196.00)
  • Thickness 4.3X40X300 mm. (€62.80)
  • Thickness 4.3X40X400 mm. (€85.50)
  • Thickness 4.3X40X600 mm. (€125.70)
  • Thickness 4.3X40X900 mm. (€188.50)
  • Thickness 4.3X40X1200 mm. (€251.40)
  • Thickness 4.3X50X300 mm. (€79.30)
  • Thickness 4.3X50X400 mm. (€108.20)
  • Thickness 4.3X50X600 mm. (€158.60)
  • Thickness 4.3X50X800 mm. (€216.30)
  • Thickness 4.3X50X900 mm. (€238.00)
  • Thickness 4.3X50X1200 mm. (€317.20)
  • Thickness 4.3X60X300 mm. (€81.90)
  • Thickness 4.3X60X600 mm. (€161.80)
  • Thickness 4.3X60X900 mm. (€241.70)
  • Thickness 4.3X60X1200 mm. (€319.60)
  • Thickness 5.3X50X400 mm. (€129.80)
  • Thickness 5.3X50X800 mm. (€259.60)
  • Thickness 5.3X60X300 mm. (€112.30)
  • Thickness 5.3X60X400 mm. (€159.70)
  • Thickness 5.3X60X600 mm. (€224.60)
  • Thickness 5.3X60X800 mm. (€319.30)
  • Thickness 5.3X60X900 mm. (€336.80)
  • Thickness 5.3X60X1200 mm. (€449.10)

Propietà of Steel M390

  • Extremely high wear resistance
  • High corrosion resistance
  • Mirror polishing
  • Excellent toughness
  • High dimensional stability
  • Improved resistance to vibration and mechanical shocks

Chemical analysis (average%)

1,900,700,3020,001,004,000,60

1.9% carbon, 20% chromium, 1% molybdenum, 4% vanadium, 0.7% silicon, 0.3% manganese and 0.6% tungsten are added for excellent resistance and thread tightness.

Steel M390

Steel M390Recommendations for heat treatment

Heat treatment from the supplier

  • Supply status: max. 280 HB
  • Optimal sweet annealing is possible only after hot molding.

Relieves stress

  • 650°C (1200°F)
  • After heating, soak for 4 hours in a neutral atmosphere.
  • Oven cooling up to 300°C (570°F), followed by air

Hardening

  • 1100 to 1180°C (2010 – 2155°F) / oil, N2
    ” Waiting time:

      • After total heating:
        – 20-30 minutes for a hardening temperature of 1100-1150 °C (2010-2100 °F)
        – 5-10 minutes for a hardening temperature of 1180 °C (2155 °F)

 

Tempering for maximum corrosion resistance

  • Subzero treatment for the processing of retained austenite
  • Slow heating at tempering temperature
  • Oven time 1 hour for every 20 mm (0.79 inches) thick of the piece, but at least 2 hours
  • Refer to the tempering table for information on hardness that can be obtained after quenching.
  • Tempering: 200 to 300 ° C (390-570 ° F)

Tempering for maximum wear resistance

  • Recommended subzero treatment
  • Subzero treatment immediately after quenching leads to tempering hardness values increased to austenitization temperatures ≥ 1150 °C
    (≥ 2100 °F), [Rischio di rottura da Stress]
  • Slow heating at tempering temperature
  • Oven time 1 hour for every 20 mm (0.79 inches) thick of the piece, but at least 2 hours
  • Refer to the tempering table for information on hardness that can be obtained after quenching.
  • Triple tempering 20 ° C (68 ° F) above the secondary hardening maximum is necessary to obtain a complete transformation of the retained austenite.

Conclusions

This steel is called “super steel” for a reason.

It surprisingly uses third-generation metal powder technology which is then developed for knife blades.

Bohler calls this steel “Microclean” and can be polished to get a real mirror.

Definitely a high-end knife steel suitable for experienced makers.

Overall, it is one of the best steels in terms of corrosion and wear resistance and for this reason it is a favorite choice for the high end and for limited edition knives.

It has been developed for knife blades that require good corrosion resistance and high hardness and excellent wear resistance.

The M390 is a fine-grained alloy and is the preferred choice for high-end locks and small fixed blades.

Are You Experience?

Andrea


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Andrea F

Maker and Enthusiast of Knifemaking. Other: Engineer / Professional Blogger / Bass Player / Instructor of Boxing / Muay Thai / Brazilian Jiu Jitsu / Grappling / CSW / MMA / Self Defence / FMA / Dirty Boxing / Silat / Jeet Kune Do & Kali / Fencing Knife / Stick Fighting / Weapons / Firearms. Street Fight Mentality & Fight Sport! State Of Love And Trust!

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