420 Steel is a large family of martensitic stainless steels that has been the industry standard for budget knives and tools for decades. It is famous for being highly rust-resistant and very tough, though its performance depends entirely on its carbon content.
In the industry, "420 Steel" usually refers to one of three main versions:
1. The Three Main Types
420J1: Very low carbon. Used for liners, handles, and cheap decorative items.
420J2: Low carbon (around 0.15%–0.36%). As we discussed, this is used for diving knives and surgical tools because it is nearly impossible to rust.
420HC (High Carbon): The "premium" version of 420. It contains significantly more carbon (about 0.45%–0.54%). When heat-treated correctly (famously by Buck Knives), it performs much better than standard 420.
Key Characteristics
Superior Corrosion Resistance: It is one of the most "stainless" steels available. It can survive salt water and humid environments better than almost any high-end "super steel."
High Toughness: Because it is relatively soft (hardened to 50–55 HRC), it is not brittle. It will bend or roll its edge rather than chipping or snapping.
Ease of Sharpening: It is incredibly easy to sharpen. You can get a 420 blade back to a razor edge in just a few minutes with a simple stone.
Low Edge Retention: This is its main weakness. Compared to the Swedish 12C27 or 19C27 we discussed earlier, 420 steel loses its sharpness very quickly under heavy use.
Chemical Composition (General 420 Series)
Carbon (C): 0.15% – 0.54% (Depends on the sub-grade)
Chromium (Cr): 12.0% – 14.0% (Provides rust resistance)
Manganese (Mn): 1.0%
Silicon (Si): 1.0%
Common Applications
Budget Pocket Knives: Used by brands like Gerber, Leatherman, and Buck (specifically 420HC).
Diving & Fishing Gear: Due to its resistance to salt water.
Surgical Scalpels: Because it can be polished to a mirror finish and resists corrosion during sterilization.
Kitchen Scissors & Gadgets: Items that are frequently washed and don't need to stay sharp for months.