Taylor Special Steels are UK and Ireland stockholders and suppliers of O1 tool steel, also known by its DIN designation 1.2510 (100MnCrW4) and BS4659 grade BO1. We hold stock in rounds, flats, and ground flat stock, cut to your required sizes as one-offs or in multiples. No order is too large or too small; contact our experienced team for a fast, competitive quote.
O1 is a standard oil-hardening, carbon-manganese cold-work tool steel offering excellent dimensional stability in heat treatment. Its vanadium content provides an advantage over comparable grades by promoting a uniformly fine grain structure across tools of varying section sizes, and gives an added safeguard against the effects of overheating during hardening. O1 is one of the most widely used general-purpose cold-work tool steels, combining good wear resistance, ease of machining in the annealed condition and consistent response to heat treatment. It achieves a working hardness in the range of 57–62 HRC and is particularly well suited to precision tooling and gauge work where close dimensional tolerances after hardening are essential.
Related Grades:
A2 Tool Steel (1.2363) | D2 Tool Steel (1.2379) | S1 Tool Steel (1.2550) | H13 Tool Steel (1.2344)
Typical uses of O1 include gauges, taps, cold punches, cold blanking and forming dies, reamers, drill bushes, straight edges, deep drawing and needle dies, engraving dies, shear blades, ground flat stock, templates and general wearing parts for machines.
O1 tool steel is widely used across toolmaking, engineering and manufacturing. Typical applications include gauges, taps, reamers, cold punches, cold blanking and forming dies, drill bushes, needle dies, deep drawing dies, engraving dies, shear blades, straight edges, ground flat stock, templates and general wearing parts for machinery.
Equivalent grades and specifications
O1 tool steel is covered by the following international standards and designations:
| Standard | Designation |
|---|---|
| DIN / Werkstoff | 1.2510 — 100MnCrW4 |
| BS4659 | BO1 |
| AISI | O1 |
| ASTM | A681 |
| BS EN ISO | 4957 |
Tools should be protected from excessive scaling or decarburisation by packing in a suitable inert material in a sealed container. Heat to 770°C / 790°C and hold for sufficient time to ensure uniformity then cool slowly at 20°C per hour to 650°C. The tools may then be withdrawn and air cooled. This treatment should result in a hardness of 229 HB maximum.
Heat to 650°C /700ºC . Hold for 2-4 hours and furnace cool.
Before heat treatment, sufficient machining should be carried out to remove surface decarburisation. Preheat thoroughly to 650°C / 700°C and then raise more rapidly to 780°C / 790°C in a controlled atmosphere furnace or, preferably, a neutral salt bath. Quench in oil. A useful alternative is box hardening using spent charcoal placed away from the working faces. Larger sections may be hardened from 810°C / 820°C.
Tools must be tempered as soon as possible following completion of the quenching operation. Heat to within 190°C / 210°C and hold for a minimum period of one hour. Longer times are advised for larger sections. The tempering curve values indicates typical hardness values obtained from oil quenching test samples from 790°C.
The diagram illustrates the time required for transformation of austenite to commence and it may be usefully employed in determining the correct temperatures and holding times for interrupted quenching treatments.
(Austenitised at 800°C)
Taylor Special Steels have been supplying specialist tool steels to UK and Irish industry for over 30 years. All O1 stock is supplied in the annealed condition and available in a wide range of round bar, flat bar and ground flat stock sizes, sawn or cut to length to your exact requirements. O1 is one of our most commonly held grades and is available for quick despatch. We supply to the manufacturing, toolmaking, aerospace and automotive industries, from single pieces to bulk orders.
If you need to compare grades, O1 is an excellent general-purpose starting point for cold-work tooling. For applications requiring greater wear resistance or improved dimensional stability on larger or more complex tools, A2 tool steel offers air-hardening characteristics with reduced distortion. For the most demanding high-volume applications, D2 tool steel provides superior wear resistance. Our team can advise on the most suitable grade for your requirements.
Call us on 0121 552 2741 or email sales@taylorspecialsteels.co.uk to discuss your O1 tool steel requirement.
Related Grades:
A2 Tool Steel (1.2363) | D2 Tool Steel (1.2379) | S1 Tool Steel (1.2550) | H13 Tool Steel (1.2344)