AISI O1 Tool Steel | 1.2510 | 100MnCrW4 | SKS3-steel round bar

What is oil O1 Steel? AISI / ASTM A681 O1 tool steel is a low alloy cold work tool steel that must be oil-quenched in heat treatment. Tools and dies made from O1 tool steel flat or rounds will have good wearing and abrasive qualities since the tungsten and higher chromium content gives improved wear resistance.

ASTM O1 tool steel has deep hardening properties with fine grain structure with unusual toughness. AISI O1 tool steel offers good durability, gives excellent wear resistance and holds a good cutting edge. O1 cold work tool steels also have a good response to heat treatment with small dimensional changes.

We are a better choice of O1 oil tool steel materials supplier with reliable quality and sales service. AISI Tool steel O1 is available in standard de-carb free rounds, flats, and squares, as well as the largest size selection in O1 oil steel ground flat stock and drill rod of all the tool steel grades, or as per customized requirements.

1. Supply Range of ASTM O1 Tool Steel

O1 Tool Steel Round Bar: diameter 8mm – 350mm

O1 Steel Plate: thickness 2mm –300mm x width 200mm – 800mm

Other sizes of O1 oil steel or as per customer’s requirements

Surface Finish: Black, Rough Machined, Turned or as per given requirements.

2. Relevant Steel Specification of AISI O1 Tool Steel

Country	USA	German	Japan
Standard	ASTM A681	DIN EN ISO 4957	JIS G4404
Grades	O1	1.2510/100MnCrW4	SKS3

3. AISI O1 Tool Steel Chemical Composition & Other Equivalents

ASTM A681	C		Mn		P	S	Si		Cr		V		W		Mo
O1	0.85	1.00	1.00	1.40	0.03	0.03	0.10	0.50	0.40	0.70	. . .	0.30	0.40	0.60	. . .	. . .
DIN ISO 4957	C		Mn		P	S	Si		Cr		V		W		Mo
1.2510	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	C		Mn		P	S	Si		Cr		V		W		Mo
SKS3	0.90	1.00	0.90	1.20	0.03	0.03		0.35	0.50	1.00	. . .	. . .	0.50	1.00	. . .	. . .

4. ASTM O1 Tool 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 psi
Compressive yield strength (0.2%, hardened to 55 HRC)	1800 MPa	261000 psi
Compressive yield strength (0.2%, hardened to 60 HRC)	2150 MPa	312000 psi
Compressive yield strength (0.2%, hardened to 62 HRC)	2200 MPa	319000 psi

• 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°C	2590°F

• Thermal Properties

Properties		Conditions
		T (°C)	Treatment
Thermal expansion	10.6 x 10-6/ºC	20-260	–

5. Forging of ASTM O1 Tool Steel

Heating for forging of oil tool steel O1 must be done slowly and uniformly. Forging of alloy O1 steels can be performed at 980-1000°C, and reheat as often as necessary. But not forge below 800°C. After forging AISI O1 tool steel, cool slowly in lime, mica, dry ashes or furnace. ASTM O-1 tool steels should always be annealed after forging.

6. AISI O1 Tool Steel Heat Treatment

• Anneal

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

Heat at a rate not exceeding 222°C per hour to 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 28°C per hourto 538°C. Continue cooling to ambient temperature in the furnace or in the air. The resultant hardness should be a maximum of 212 HBW.

• Stress Relief of Unhardened Material

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

• Hardening

1. Preheat: Warm slightly before charging into the preheat furnace, which should be operating at about 1100°-1200°F.
2. Hardening: Heat to 1475 to 1500° F. Soak at heat for 30 minutes per inch of thickness.
3. Quench: Quench O1 steel in warm oil and allow to cool in the oil until a temperature of 125°-150°F has been reached, or to where the part can be held in the bare hand, and temper immediately.
4. Temper: Normally oil hardening steels need to be single tempered only. However, double tempering may sometimes be preferred. Soak at heat for 2 hours per inch of thickness for each temper. Air cool to room temperature between tempers. The normal tempering range for this grade is 300 to 450° F.

•  Stress Relief Temper

A stress relief temper for the hardened material is strongly recommended after significant grinding, or welding, or EDM. Select a temperature that is 25 or 50° F lower than the last tempering temperature used.

7. Applications for ASTM A681 O1 Tool Steel

O1 steels are 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, punches, bolster dies, knock-out pins, thread roll dies, bending dies, plastic mold dies, shims, cams, machine ways, stamps, machine parts, jigs, cutter templates, swaging dies, etc.

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