AISI / USA

O1

Carbon Tool Steel57–64 HRCConventional Ingot Steel Process

Composition

Core alloying elements define the baseline trade-off between wear resistance, corrosion behavior, and toughness.

Material Overview

O1 is a traditional high-carbon tool steel originally developed for industrial tooling applications. It is highly valued in the knife industry for its fine grain structure, excellent edge stability, and ease of heat treatment. O1 can achieve very sharp edges while maintaining good toughness, making it popular among custom knife makers and bushcraft enthusiasts. However, because it is a non-stainless steel, regular maintenance is required to prevent rust and patina formation.

Performance Radar

Use four core metrics to understand the usable operating envelope of this steel at a glance.

Edge Retention

Toughness

Corrosion Resistance

Sharpenability

Edge Retention

8.0

Toughness

8.0

Corrosion Resistance

3.0

Sharpenability

9.0

Advantages

Excellent toughness
Easy to sharpen
Fine grain structure for razor-sharp edges
Stable and predictable heat treatment
Popular for custom and bushcraft knives

Disadvantages

Low corrosion resistance
Requires regular maintenance to prevent rust
Edge retention lower than modern high-vanadium PM steels

At A Glance

O1 is a classic oil-hardening carbon tool steel known for excellent toughness, easy sharpening, and fine edge stability, widely used in custom knives and woodworking tools.