What is a stainless steel, in general?

In rough figures we can say that the stainless steel has been around for about a hundred years only while the high carbon steel is well known for more than a thousand years. So what is a stainless steel? In metallurgy, stainless steel, also known as inox steel, is a steel alloy with a minimum of 10.5% chromium content by mass.

Stainless steel does not corrode very easy. However, it isn’t fully rust-proof in low-oxygen, high-salinity, or poor air-circulation environments. There are different grades and surface finishes of stainless steel to suit the environment the alloy must manage. Stainless steel is used when both the properties of steel and corrosion resistance are required. Treating a stainless steel knife with some common sense, you will have a problem-free knife for many years.

Stainless steel differs from high carbon steel by the amount of chromium present. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal’s internal structure. Due to the similar size of the steel and oxide ions, they bond very strongly and remain attached to the surface.

Laminate steel – why?

We’re using a laminate steel because such a steel is at least 20 % stronger than a solid stainless steel. Designing a survival knife you always have to consider about the strength of the knife since you might be forced to use the knife beyond standards. Usually we go for strong low/medium carbon stainless steel for the outer layers and add VG10, Cobalt-Special or Super Gold Powder Steel as a center steel. The 420J2 is a low-carbon high chromium alloy steel and we are using that because of its strength and its almost corrosion-free properties. We’re using VG5 stainless steel as well and, with a higher carbon content, the VG5 steel is less scratch sensitive than the 420J2, a little stronger but also more expensive and tougher to work.

The different types of steel we use:

Rockwell HRC
3GVG2 – SGPS – VG262
Cowry X120 layers damast steel with an edge in Cowry X64
Laminated CoS420J2  –  CoS  –  420J260
Laminated SGPS420J2 – SGPS – 420J262
Laminated VG10420J2  –  VG10  –  420J259

Steel analysis :

VG10 (59 HRC)
SGPS (edge) (62 HRC)
CoS (60 HRC)
Cowry X (64 HRC)
C – 1.00C – 1.40C – 1.10C – 3.00
Si – 0.60Si – 0.50Si – 0.0Cr – 20.00
Mn – 0.50Mn – 0.40Cr – 16Mo – 1.00
P – 0.030P – 0.030W – 0.3V – 0.30
Cr – 15.00Cr – 15.00Mo – 1.5
Mo – 1.05Mo – 2.80Co – 2.5
Co – 1.40S – 0.030P – 0.0
V – 0.20V – 2.00V – 0.3

These steel form the edge:

Cowry X: An extreme powder steel developed by Mr. Ichiro Hattori
SGPS: Super Gold Powder steel
CoS: A newly developed high alloy cobalt-special steel
VG10: A well known high alloy molybdenum/cobalt steel
VG2: A standard semi alloy strong stainless steel
420J2: A standard low carbon durable stainless steel

Which knives are using which steel?

Cowry X: HK9cx, NL5cx
3G: SK1 (Jarl), SK3 (Juni), HK9, FH9, FH9mop, FH9s, TK1, TK2, TK3, TK4, TK5, TK6, U1, P/3G, PXL, WM1/3G, H1/3G, PHK, F1/3G, F1/3Gmm, F1/3Gbm, LTC
Lam. SGPS: U2, U4
Lam. CoS: SK6 (Krut), V1, GP, FH9bh, PXLx, PXLwh, Alpha, Delta, Sierra, Zulu, KK, F1pro, S1pro, A1pro, F1d, PC, PCx, SK18 (Erna), MB (Modern Bowie)
Lam. VG10: NL1 (Tor), NL2 (Odin), NL3 (Njord), NL4 (Frej), NL5 (Idun), F1, F2, F3, F4, K1, K2, WM1, H1, S1, A1, A2