AISI O1 Steel Round Bar Sheet Plate, DIN 1.2510, JIS SKS3

O1 steel also is called DIN 1.2510 and JIS SKS3 steel. High content for manganese, chromium and tungsten in 1.2510 steel composition, that could increase the hardening ability. Then the steel does not need to undergo water quenching. After oil cooling and quenching, the hardness could reach 62HRC. O1 tool steel round bar sheet plate was used widely as a cold work mold steel. It is a great material for the blade, metal molds and etc. O1 steel properties and O1 steel heat treat as below.

O1 Steel Grade Equivalent Chart

Country  USA Germany/UK/France JAPAN
Standard ASTM A681 DIN EN ISO 4957 JIS G4404
Grades O1 1.2510/100MnCrW4 SKS3

O1 Steel Chemical Composition and Equivalent Grades

STAND C (%) Mn(%) P(%) S (%) Si (%) Cr (%) V(%) W (%) Mo(%)
ASTM A681 0.85-1.00 1.00-1.40 0.03 0.03 0.10-0.50 0.40-0.70 0.40-0.60
EN ISO 4957 0.90-1.05 1.00-1.20 0.03 0.03 0.15-0.35 0.50-0.70 0.05-0.15 0.50-0.70
JIS G4404 0.90-1.00 0.90-1.20 0.03 0.03 max 0.35 0.50-1.00 0.50-1.00

1.2510 Steel Physical Properties

Properties Metric Imperial
Density(hardened to 62 HRC) 7.81 g/cm³ 0.282 lb/in³
Density(@399°C/ 750°F, hardened to 62 HRC) 7.70 g/cm³ 0.278 lb/in³
Density(@191°C/ 375°F, hardened to 62 HRC) 7.75 g/cm³ 0.280 lb/in³
Melting point 1421℃ 2590°F

O1 Steel Mechanical Properties

Properties Metric Imperial
Hardness, Brinell(soft annealed -delivery condition) 190 190
Hardness, Rockwell C(tempering temp 300-1200°F) 34.0-64.0 34.0-64.0
Elastic modulus(hardened to 62 HRC) 193 GPa 28000 ksi
Elastic modulus(@399°C/750°F, hardened to 62 HRC ) 172 GPa  25000 ksi
Elastic modulus(@191°C/375°F, hardened to 62 HRC) 186 GPa 27000 ksi
Compressive yield strength(0.2%, hardened to 50 HRC) 1350 MPa 196000 ksi
Compressive yield strength(0.2%, hardened to 55 HRC) 1800 MPa 261000 ksi
Compressive yield strength(0.2%, hardened to 60 HRC) 2150 MPa 312000 ksi
Compressive yield strength(0.2%, hardened to 62 HRC) 2200 MPa 319000 ksi

1.2510 Steel Characteristics

1.It is pre-hardened, texture consistent, high hardenability.
2.High cleanliness and excellent polishing performance.
3.Good electrical processing properties and texture processing properties.

O1 Steel Application

O1 Steel Application

1.2510 steel is used as a material of tough parts. Such as punches, knock-out pins, cams, and of course, knife blades. And 1.2510 steel is mainly used for short-run tooling for cold forming dies, blanking dies, and cutting tools operating at ambient temperature. Typical applications for O1 tool steel are blanking, forming, and trim dies, gages, slitting cutters and etc.

O1 Steel Round Bar Sheet Plate Heat Treatment

Stress Relief of Unhardened Material
Heat slowly to 1250° F. Soak for two hours per inch of thickness at heat. Slow cool (furnace cool if possible) to room temperature.

Critical Temperature:
Ac1: 1350°F Ac3: 1400°F
(732°C) (760°C)
Ar1: 1295°F Ar3: 1240°F
(703°C) (671°C)

Heat at a rate not exceeding 400°F per hour (222°C per hour) to 1200-1300°F (649-704°C) and equalize.

Austenitizing (High Heat)
Heat slowly from the preheat to 1475-1500°F (802-816C)

Soak for 30 minutes for the first inch (25.4 mm) of thickness, plus 15 minutes for each additional inch (25.4 mm).

Oil quenching to a temperature no lower than 150-125°F (66-51°C).


O1 steel is prone to quench cracking, especially if there are significant changes in section thickness and sharp internal corners. The oil quenching should be performed so that the heat removal is as uniform as possible in all areas of the part being quenched. Be sure to remove the part from the oil before the temperature drops to ambient temperature. Hot oil at a temperature of 300 to 400°F (149-204°C) is recommended.

Temper immediately after quenching. Do not allow the part to cool below 125°F (51°C). The typical tempering range is 350 – 400°F (177 -204°C). Hold at temperature for 1 hour per inch (25.4 mm) of thickness, 2 hours minimum, then air cool to ambient temperature. To minimize internal stresses in cross sections greater than 3 inches (76.2 mm) and to improve stability in parts that will be EDM’d after heat treatment, a soaking time of 4 to 6 hours at the tempering temperature is strongly recommended.

Cryogenic Treatment
Refrigeration treatments should typically be performed after the temper, and must be followed by a second temper.

Annealing must be performed after hot working and before re-hardening.

Heat at a rate not exceeding 400°F per hour (222°C per hour) to 1425 -1450°F (802-816°C), and hold at temperature for 1 hour per inch (25.4mm) of maximum thickness; 2 hours minimum. Then cool slowly with the furnace at a rate not exceeding 50°F per hour (28°C per hour) to 1000°F (538°C). Continue cooling to ambient temperature in the furnace or in air. The resultant hardness should be a maximum of 212 HBW.

O1 Steel Quality Certificate Certificate & SGS Report

O1 Steel Quality Certificate Certificate & SGS Report

O1 Steel Round Bar Sheet Plate Supply

Round Bar

Specification: Dia 20-600mm; Length: <5800mm(fit 20ft container); >5800mm, 40ft container
Surface: original black, peeled, machined/turned, polished/ grounded/milled/grinded


Specification: thickness: 10-600mm; width: 30-810mm; length: same as above
Surface: original black, machined/turned, polished/ grounded/milled/grinded


We have our own cutting and processing equipment. Specifications can be cut and customized according to your requirements.

We are a professional special steel stockist and supplier with a high-quality stand for many years. Please contact us for any request of O1/1.2510 steels materials. Songshun Steel always with you.