The Heart of a Folding Knife: Unveiling the Pros and Cons of 5 Common Blade Materials

October 28, 2025

When selecting a folding knife, the blade material is a key factor determining its performance and price. No single material is perfect; each represents a trade‑off between hardness, toughness, corrosion resistance, and ease of sharpening.

Here are five common blade materials for folding knives:

1. 440C Stainless Steel – The Timeless Classic

Characteristics: A historic high‑carbon stainless steel known for its excellent corrosion resistance (rust resistance).

Pros: Cost‑effective, very rust‑resistant, easy to sharpen.

Cons: Relatively poor edge retention (how long it stays sharp), requires more frequent sharpening. Hardness is slightly insufficient for heavy‑duty use.

Best For: Light tasks for Everyday Carry (EDC), diving knives, entry‑level or vintage‑style folding knives.

2. AUS‑8 Stainless Steel – The Japanese Balanced Choice

Characteristics: A mid‑to‑high‑end stainless steel produced in Japan, known for its balanced performance.

Pros: Offers good toughness (resistance to chipping), decent corrosion resistance, and good sharpenability. It strikes an excellent balance between hardness, toughness, and rust resistance.

Cons: Edge retention is better than 440C but still falls short of more advanced powder steels.

Best For: An excellent “all‑rounder” steel, suitable for general‑purpose daily folding knives that meet most cutting tasks.

3. 8Cr13MoV – China’s King of Value

Characteristics: With a chemical composition similar to AUS‑8, this is a widely used steel produced in China.

Pros: Very affordable, while offering good overall performance: easy to sharpen, with decent toughness and acceptable corrosion resistance.

Cons: Average edge retention, on par with or slightly lower than AUS‑8.

Best For: Often used in entry‑level and budget‑friendly knives from well‑known brands. A great choice for beginners.

4. D2 Tool Steel – The “Semi‑Stainless” Hardened Steel

Characteristics: D2 is a high‑carbon, high‑chromium tool steel highly regarded for its extreme hardness and outstanding edge retention.

Pros: Exceptional edge retention, very wear‑resistant.

Cons: Its chromium content is insufficient to be classified as “fully stainless,” so it may rust in humid environments and requires more maintenance. It is also relatively difficult to sharpen.

Best For: Folding knives intended for heavy‑duty tasks requiring long‑lasting sharpness, for users willing to invest more effort in maintenance.

5. CPM‑S30V – The Star of Modern Powder Metallurgy

Characteristics: Manufactured by Crucible Industries in the USA using the Particle Metallurgy (CPM) process, representing a leap forward in modern knife‑steel technology.

Pros: Achieves high levels of edge retention, hardness, and corrosion resistance simultaneously, with good toughness. It was designed to eliminate the trade‑offs of traditional steels.

Cons: Expensive, can be challenging for beginners to sharpen.

Best For: The preferred material for professional‑grade, high‑end folding knives, suited for users seeking ultimate performance, collectors, and outdoor enthusiasts.

How to Choose?

• Daily Use: AUS‑8 or 8Cr13MoV offer the best balance.
• Heavy‑Duty Outdoor Use: D2 or CPM‑S30V provide longer‑lasting sharpness.
• Coastal/Humid Environments: Prioritise 440C or CPM‑S30V for enhanced rust resistance.
• Budget & Easy Maintenance: 440C and 8Cr13MoV are economical and easy to sharpen yourself.