Is 420 Stainless Steel Good for Knife Making? Hardness and Grade Comparison
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Short Answer: Yes, with Conditions
420 stainless steel is a martensitic, hardenable grade containing 12-14 % chromium and 0.15 % carbon or more, so it can be quenched and tempered to about 50-55 HRC. That hardness makes it perfectly serviceable for table cutlery, pocket knives, scissors and light-duty utility blades, and its chromium content gives far better stain resistance than the plain carbon steels used in traditional blades. It is not, however, a high-end cutlery steel: the lowest-carbon 420 holds an edge for a comparatively short time, while higher-carbon variants such as EN 1.4034 / X46Cr13 and 420HC perform distinctly better.
Composition and Standard Designations
Type 420 is standardised in ASTM A276 with 0.15 % minimum carbon, 12.0-14.0 % chromium, 1.00 % maximum manganese and silicon, and 0.040 % maximum phosphorus. The commercial variants differ mainly in carbon, which is what separates a serviceable blade from a good one.
| Designation | Carbon | Chromium | Knife-making behaviour |
|---|---|---|---|
| AISI 420 (2Cr13, EN 1.4021) | 0.16-0.25 % | 12.0-14.0 % | Tough and corrosion resistant, modest edge retention |
| AISI 420HC | 0.40-0.50 % | 12.0-14.0 % | Better edge retention, still easy to sharpen |
| EN 1.4034 / X46Cr13 | 0.42-0.50 % | 12.5-14.5 % | Higher hardness, suited to cutting tools and instruments |
| EN 1.4116 / X50CrMoV15 | 0.45-0.55 % | 14.0-15.0 % | Molybdenum and vanadium added for kitchen knives |
| AISI 440C | 0.95-1.20 % | 16.0-18.0 % | Very high wear resistance, lower toughness |
Hardness and Edge Behaviour
In the annealed condition 420 round bar is soft and machines easily, with tensile strength of 850 MPa or less; after hardening the practical hardness for blades is 52-54 HRC. Raising carbon and adding molybdenum or vanadium lets the steel carry a harder, more stable edge and resist softening if the blade heats up during grinding. Above roughly 56 HRC toughness starts to fall and the risk of chipping on hard use rises, so most production knives are tempered in the 150-200 °C range rather than pushed to the maximum. Compared with 440C, 420 is tougher and easier to sharpen but wears faster; compared with a simple carbon steel it resists staining far better but cannot match the finest achievable edge.
Knife-Making and Fabrication Notes
Cut and shape the blank in the annealed condition, because hardness above 35 HRC quickly consumes tooling
Austenitize in the 1000-1060 °C range, then quench in oil or air according to the section size
Temper immediately after quenching, typically at 150-200 °C for maximum hardness or higher for toughness
A sub-zero treatment is used where dimensional stability matters, for example on precision instrument blades
Finish grinding, passivation and edge honing follow heat treatment, since the final dimensions must be set after the transformation
Straightness should be checked after hardening, as thin blades tend to distort; correcting it requires a controlled temper and press rather than cold bending.
Typical Applications
Beyond cutlery, the grade is used for surgical instruments such as scalpels, forceps and scissors, for cutting edges such as shear blades, slitting knives and industrial blades, and for screwdriver bits, saw blades, gauges and mould parts, where hardness and wear resistance are the deciding factors. High-speed cutting tools such as twist drills and milling cutters normally use tool steels or higher-alloy grades rather than 420, because the temperature at the cutting edge exceeds what this family can sustain.
Frequently Asked Questions
Q: Is 420 stainless steel good for knife making?
Yes for everyday cutlery, utility knives and scissors, where it gives a good balance of hardness, toughness and stain resistance. For demanding edge retention, higher-carbon grades are better.
Q: What hardness can 420 reach?
About 52-54 HRC after hardening and low-temperature tempering. Pushing beyond roughly 56 HRC increases the risk of chipping in service.
Q: How does 420 compare with 440C?
440C contains far more carbon and chromium, so it resists wear longer but is less tough and harder to sharpen. 420 is the tougher, more forgiving steel.
Q: Is 420 stainless steel rust proof?
No stainless steel is rust proof. 420 stains far less than carbon steel but can rust in prolonged moisture or salt exposure, so drying and light oiling still matter.
Q: Which 420 variant should a knife maker choose?
For a tough working blade, standard 420 or 420HC; for higher hardness and better edge holding, EN 1.4034 / X46Cr13; for kitchen knives, the molybdenum-bearing 1.4116 type.
Q: Does 420 keep a good edge?
It holds an edge well enough for general kitchen and utility use and can be resharpened easily, but it will need honing sooner than high-carbon or powder-metallurgy cutlery grades.
