O1 is an oil hardening cold-work tool steel.

It is a carbon manganese tool steel, possessing excellent dimensional stability during heat treatment.  O1 is used for the production of ground flat stock, a precision material used in tool making and other engineering applications.


O1 Typical Analysis
Carbon 0.95% Manganese 1.25%
Chromium 0.50% Tungsten 0.50%
Vanadium 0.20%

Typical Applications

Typical applications

Press tools & broachesClipping, Marking PunchesGaugesJigs
Rotary CuttersWear platesGaugesScrewing tools
Ground Flat StockSlitting CuttersDeep Drawing DiesTaps

Related specifications

AISI O1 is a close equivalent to: 

Werkstoff nr. 1.2510BS BO1BS UNS T31501SAE J437

Our range

Our stock sheets are all supplied in the annealed condition. We typically supply O1 in a range of sheet sizes, from 2.46mm through to 8.65mm thick in a hardness of around 200vpn.

We do not supply Mill Certificates with orders, we only supply Certificates of Conformity.

Please contact us on 0114 244 0527 (option 2) to make an enquiry.