Steel O1 · temper · default condition
Steel O1 Annealed
Properties of the Annealed condition, compared with the other O1 tempers.
Standard stock condition for machining, sawing and drilling before hardening.
What is O1 Annealed?
O1 Annealed is O1 in the Annealed temper — standard stock condition for machining, sawing and drilling before hardening. O1 Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). O1 Annealed 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).
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 76% of steel grades
Limitations
- Difficult to weld — 20/100, worse than 84% of steel grades
O1 Annealed properties
Typical room-temperature values for O1 Annealed — 14 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 Annealed 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 Annealed has a yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 60% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
O1 Annealed is rated for continuous service to 400°C (752 °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 Annealed 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 Annealed 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 Annealed's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (20/100); formability fair (35/100).
Common Calculations5
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 Annealed
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 Annealed — frequently asked
What is O1 Annealed used for?
O1 Annealed 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 Annealed?
O1 Annealed has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is O1 Annealed easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% 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 Annealed 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 Annealed?
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 Annealed 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 Annealed?
O1 Annealed is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in O1 Annealed?
Yes — O1 Annealed 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.