420J2 Steel is a low-carbon, high-chromium martensitic stainless steel. It is widely considered an entry-level or "budget" steel in the knife industry, very similar to the 3Cr13 steel we just discussed.
It is prized by manufacturers for being extremely cheap to produce and highly resistant to rust, though it lacks the hardness required for high-end professional tools.
Key Characteristics
Extreme Corrosion Resistance: This is its greatest strength. It is highly resistant to rusting in wet or salty environments, which is why it's common in diving knives and kitchen shears.
High Toughness & Flexibility: Because it is a "soft" steel (typically hardened to 52–54 HRC), it is very difficult to break or chip. It will bend before it snaps.
Poor Edge Retention: Due to its low carbon content, it does not stay sharp for long. If you use a 420J2 knife for heavy cutting, you will need to sharpen it frequently.
Very Easy to Sharpen: Even a beginner can bring a 420J2 blade to a razor edge very quickly using basic sharpening tools.
Chemical Composition
420J2 is part of the "420" series, but the "J2" indicates a specific formulation optimized for polish and corrosion resistance:
Carbon (C): 0.15% – 0.36% (Very low; for comparison, 19C27 has 0.95%)
Chromium (Cr): 12.0% – 14.0% (Provides the "stainless" quality)
Manganese (Mn): 1.0% max
Silicon (Si): 1.0% max
Common Equivalents
3Cr13 (Chinese GB Standard)
1.4028 (German DIN Standard)
SUS420J2 (Japanese JIS Standard)
Common Applications
Diving & Fishing Knives: Where constant exposure to water makes rust resistance the #1 priority.
Surgical Instruments: It can be polished to a mirror finish and sterilized easily.
Liners and Handles: In high-end folding knives, the blade might be a premium steel (like S35VN), but the internal liners are often 420J2 because they need to be tough and rust-proof.
Budget Multi-tools: Brands like Leatherman often use 420HC (a higher-carbon version) for blades, but use 420J2 for the handles or secondary tools like scissors.
Novelty/Fantasy Swords: Most decorative swords found in gift shops are made of this steel.