Grade O1/ 1.2510/ 90MnCrV8, is a widely used oil-hardening cold-work tool steel known for its excellent combination of machinability, toughness, edge retention, and dimensional stability.

O1 is considered one of the most versatile tool steels, offering consistent performance at a cost-effective price. It is commonly used for cutting tools, knives, gauges, and precision tools that require sharp edges and reliable hardness.

O1 is supplied in annealed form (typically 200–230 HB) and can be hardened to 57–63 HRC depending on the application.

Key Properties of O1/ 1.2510

1. Excellent Machinability (Better Than D2/D3)

Being a low-alloy tool steel, O1 machines very easily in its annealed condition. It is preferred when:

a. Easy shaping and machining are required

b. Complex tooling must be milled or turned

c. Lower machining costs are needed

2. Good Hardness (57–63 HRC After Heat Treatment)

O1 achieves high hardness through simple oil quenching, making heat treatment easier and more forgiving compared to air-hardening steels like D2.

3. Good Wear Resistance

While not as hard-wearing as D2, it provides consistent wear resistance suitable for:

a. Medium-duty cutting tools

b. Punches and dies

c. Precision blades

4. Excellent Dimensional Stability

O1 has low distortion during heat treatment, making it ideal for:

a. Gauges

b. Precision tools

c. Fine-edge instruments

5. Good Toughness

Compared to high-carbon chromium steels (D3), O1 has better toughness and is less likely to chip or crack under moderate shock loads.

6. Fine Edge Retention

The presence of chromium, tungsten, and vanadium carbides allows O1 to maintain a sharp cutting edge longer than plain carbon steels.

Common Applications of O1/ 1.2510

1. Punches and small dies

2. Industrial machine knives

3. Cutting tools and blades

4. Woodworking tools (chisels, plane blades)

5. Gauges & measuring tools

6. Reamers, taps, broaches

7. Plastic mould inserts (low wear areas)

8. Knives (industrial and handmade)

Summary

O1 / 1.2510 is a highly versatile, oil-hardening tool steel offering a combination of good hardness, toughness, machinability, and dimensional stability. It is especially useful for tools requiring sharp edges and dependable wear resistance.
Because of its easy heat treatment and excellent edge retention, O1 remains a top choice for precision tools, knives, and cold work applications.