Steel O1 · heat-treated state
Steel O1 Q&T
Properties of the Q&T condition, compared with the other O1 tempers.
Generic supplied-hardened condition when a hardness band rather than an exact temper is specified.
What is O1 Q&T?
O1 Q&T is O1 heat treated to Q&T — generic supplied-hardened condition when a hardness band rather than an exact temper is specified. O1 Q&T has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 99% of steel grades. Elongation at break is 2% and the elastic modulus is 205 GPa (29.7 Msi). O1 Q&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- High strength — 1,800 MPa (261 ksi), better than 99% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 100% of steel grades
- Limited ductility — 2%, worse than 99% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
O1 Q&T properties
Typical room-temperature values for O1 Q&T — 10 properties are specific to this condition; the rest are grade-level values shared by every O1 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
O1 Q&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
O1 Q&T has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 99% of steel grades. Elongation at break is 2% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
O1 Q&T is rated for continuous service to 200°C (392 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 74% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
O1 Q&T conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of O1 Q&T takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 40%.
Manufacturability6
O1 Q&T's machinability is not recommended (10/100, worse than 100% of steel grades); weldability poor (20/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other O1 tempers and conditions
O1 is also supplied in 8 other conditions. The full side-by-side table is on the O1 overview.
- AnnealedDefaultStandard stock condition for machining, sawing and drilling before hardening.400 MPa yield · 200 HB
- H 62-64 HRCMaximum hardness for knife blades, reamers, hand tools and gauges where toughness is secondary.2,050 MPa yield · 63 HRC
- Hardened & TemperedStandard working condition for blanking dies, punches and gauges where maximum wear resistance is wanted.1,900 MPa yield · 61 HRC
- Q&TGeneric supplied-hardened condition when a hardness band rather than an exact temper is specified.1,800 MPa yield · 59 HRC
- Q&T 57-59 HRCBalanced hardness/toughness for punches and shear blades that see impact loading.1,750 MPa yield · 58 HRC
- Q&T 54-56 HRCToughest practical working hardness for heavily shock-loaded chisels, cold heading and forming tools.1,600 MPa yield · 55 HRC
Working with O1 Q&T
Is O1 easy to machine?
Machines and grinds well at 190–210 HB (≈42 % of 1212); after hardening only grinding, EDM or CBN work — rough machine soft, stress relieve, then finish.
Can O1 be welded?
Poor weldability; if repair welding is unavoidable preheat to 300–350 °C, use matching or low-hydrogen high-alloy filler, and temper immediately to avoid quench cracks.
Can O1 be formed, bent or molded?
Cold form only in the annealed state and with generous radii; hot work 900–1050 °C with slow furnace cooling, then spheroidize anneal at 760–790 °C. Harden 790–815 °C, oil quench, temper 150–400 °C; dimensional change is small, ~+0.05 % typical.
What surface finishes work on O1?
Takes a high polish and mirror finish when hardened; protect bare surfaces with oil, black oxide, phosphate or nitride/PVD coating since the steel has no corrosion resistance.
O1 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CASTM A681 O1 | 0.85 – 1 | 0.92 |
| Mn | 1 – 1.4 | 1.2 |
| Si | 0.1 – 0.5 | 0.3 |
| Cr | 0.4 – 0.6 | 0.5 |
| W | 0.4 – 0.6 | 0.5 |
| Voptional / max | ≤ 0.3 | 0.1 |
| Moresidual, not required | ≤ 0.3 | — |
| Niresidual | ≤ 0.3 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
O1 Q&T — frequently asked
What is O1 Q&T used for?
O1 Q&T is typically used for blanking and trimming dies, hand and machine cutting tools, knife and shear blades, gauges and templates, cold forming tools and punches and die inserts. In short: classic oil-hardening tool.
What is the yield strength of O1 Q&T?
O1 Q&T has a typical yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,100 MPa (305 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is O1 Q&T easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% of steel grades). Machines and grinds well at 190–210 HB (≈42 % of 1212); after hardening only grinding, EDM or CBN work — rough machine soft, stress relieve, then finish.
Can O1 Q&T be welded?
Not readily — weldability is rated poor (20/100). Poor weldability; if repair welding is unavoidable preheat to 300–350 °C, use matching or low-hydrogen high-alloy filler, and temper immediately to avoid quench cracks.
What surface finishes work on O1 Q&T?
Takes a high polish and mirror finish when hardened; protect bare surfaces with oil, black oxide, phosphate or nitride/PVD coating since the steel has no corrosion resistance.
Can O1 Q&T be formed, bent or molded?
Cold form only in the annealed state and with generous radii; hot work 900–1050 °C with slow furnace cooling, then spheroidize anneal at 760–790 °C. Harden 790–815 °C, oil quench, temper 150–400 °C; dimensional change is small, ~+0.05 % typical.
What is the maximum service temperature of O1 Q&T?
O1 Q&T is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in O1 Q&T?
Yes — O1 Q&T is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A681 Standard Specification for Tool Steels, Alloy — ASTM International (2020)
- DIN EN ISO 4957 Tool steels (100MnCrW4 / 1.2510) — DIN/ISO (2018)
- GB/T 1299 (9CrWMn) — SAC (2014)
- ASM Handbook Vol.1: Properties and Selection — Tool Steels — ASM International (1990)
- Uddeholm Arne (AISI O1) datasheet — voestalpine Uddeholm (2023)
- Böhler K460 (1.2510) datasheet — voestalpine Böhler Edelstahl (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.