N690 steel, produced by Bohler, and 154CM steel, an older steel manufactured by renowned companies like Crucible Steel, are two budget-friendly knife stainless steel options.
They are similar high-carbon chromium steels often compared to 440C, but with some key compositional differences.
The main distinction is that N690 steel contains a significant addition of 1.5% cobalt, while 154CM steel does not.
This addition of cobalt gives N690 improved tempering resistance and secondary hardening capabilities compared to 154CM.
In terms of knife properties, N690 offers slightly better corrosion resistance thanks to its higher 17.3% chromium content versus 14% in 154CM.
N690 vs 154CM Steel At A Glance
| Property | N690 Steel | 154CM Steel |
|---|---|---|
| Corrosion Resistance | Better than 154Cm (17.3% Cr) | Good (14% Cr) |
| Hardness | 62 HRC max | 64 HRC max |
| Toughness | Comparable | Comparable |
| Wear Resistance | Good (12% carbides) | Better than N690 (17.5% carbides) |
| Edge Retention | Good | Good, slightly better at higher hardness |
| Ease of Sharpening | Easier | More difficult |
Corrosion Resistance
N690 has slightly better corrosion resistance than 154CM thanks to its higher 17.3% chromium content compared to 14.0% in 154CM,
This makes N690 steel more favorable for kitchen knives and knives where maximum corrosion resistance is needed.
Bohler N690 about 11.79% of chromium is left in the solution to fight corrosion while in 154CM only about 9.5% is left in the solution while the other amount is used up in the formation of carbides.
For knives, the superior corrosion resistance of N690 makes it a better choice for kitchen knives where staining and rusting from food acids is a concern.
N690 stainless steel can maintain a cleaner, more stain-free surface compared to 154CM stainless steel.
Toughness
Toughness is the ability of a knife to resist chipping, cracking, or breaking under impacts or use.
When comparing the toughness of N690 and 154CM steels, there is no clear winner, both exhibit similar levels of toughness that are comparable to D2 steel and slightly less than VG10 steel.
The high carbon content of around 1% in both 154CM and N690 leads to significant carbide formation.
The higher carbide volume fraction in 154CM contributes to its high wear resistance but also reduces its toughness.
Similarly, the high 17.3% chromium content in N690 betters its corrosion resistance but then lowers its toughness.
The addition of 1.5% cobalt in N690 is also detrimental to toughness.
So while N690 has the potential for higher toughness based on composition, the high amounts of chromium and carbides in both steels limit their toughness.
For knives, the comparable toughness of N690 and 154CM means neither knife steel has a distinct advantage in impact or shock resistance.
Their toughness levels fall between 440C and VG10 stainless steel, not quite as high toughness as CPM 154 but superior to 440C.
Hardness
N690 steel has a maximum hardness of around 62 HRC, while 154CM steel can achieve slightly higher hardness with a maximum of 64 HRC.
154CM stainless steel typically achieves higher hardness than N690 stainless steel due to a higher amount of carbon in solution at around 0.41% compared to 0.38% for N690.
154CM has slightly higher hardness compared to N690, when properly heat treated, giving it a better range of heat treatment for different types of knives.
Bohler N690 has a better secondary hardening response thanks to small additions of cobalt and molybdenum.
Edge Retention
The edge retention and wear resistance of N690 and 154CM stainless steels are fairly comparable.
In knives, they achieve highly similar edge retention but 154CM is capable of achieving higher edge retention when heat treated to a higher hardness level.
154CM blade steel has a slightly higher volume fraction of carbides at 17.5% compared to 12% for N690 steel.
This contributes to the better wear resistance of 154CM seen in pin abrasion testing, with a wear resistance value of 49 mg compared to 55-66 mg for N690 where the values represent weight loss, lower is better.
However, the difference is relatively small. And their attainable hardness values are very similar, in the low 60s HRC range.
So in practical knife use, both N690 and 154CM can be expected to have excellent edge retention and wear resistance thanks to their high hardness.
The chromium carbides in both steels also impart good abrasion resistance.
Ease of Sharpening
N690 is easier to sharpen and grind than 154CM for knives, thanks to its lower volume fraction of hard carbides.
This is likely due to the lower volume fraction of chromium carbides in N690 – around 12% vs 17.5% for 154CM.
The higher carbide content in 154CM makes it more difficult to abrade and remove material during grinding and sharpening.
This gives N690 an advantage when it comes to the ease and speed of putting an initial fine edge on knife blades for the end user and manufacturers.
Final Thoughts on N690 vs 154CM Steel
I have knives made from both steels and honestly could not discern much of a difference in real-world performance.
They both exhibit good edge retention, corrosion resistance, and wear resistance.
However, N690 does have a slight advantage in corrosion resistance thanks to its higher chromium content.
N690 steel is also a bit easier to sharpen compared to 154CM with its higher carbide volume.
I’d likely recommend N690 over 154CM for someone picking a knife with these steels.
While 154CM is undoubtedly great steel, N690 seems just a bit more forgiving on maintenance, and easy to sharpen over time.
But whether you opt for N690 or 154CM, you really can’t go wrong – both offer an amazing combination of properties for knife blades.
They punch well above their budget-friendly price tags, offering performance rivaling premium stainless steels.
While they may not beat out some of the more exotic powder metallurgy steels, N690, and 154CM are excellent choices for do-it-all stainless steel knives.