Steel O2
AISI/SAE O2 · UNS T31502 · EN 1.2842, 90MnCrV8 · GB 9Mn2V
O2 (1.2842 / 90MnCrV8, UNS T31502, also 9Mn2V) is a manganese-alloyed oil-hardening cold-work tool steel, close to O1 but with higher manganese for greater hardenability from a low austenitizing temperature.
Values for the Annealed condition
O2 tempers and conditions
O2 is supplied in 5 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault spheroidize annealed (soft, as-supplied bar / ground flat stock) | Standard stock condition for machining, drilling and grinding before hardening. | 420 | 740 | 25 | 205 HB | — |
h9–h11 bar and flat stock | Annealed material supplied to close size and finish so only the working faces need machining. | 520 | 800 | 15 | 19 HRC | 8 % IACS |
Hardened & Tempered 54–56 HRC | Highest-toughness tempered condition for shear blades and impact-loaded punches. | 1,600 | 1,850 | 3 | 55 HRC | 6.6 % IACS |
oil quench + 150–200 °C temper | Standard working condition for blanking dies, gauges and knife/cutting edges needing maximum wear resistance. | 1,900 | 2,200 | 1 | 61 HRC | — |
790–815 °C, oil quench, untempered | Intermediate condition only — maximum hardness but brittle; must be tempered immediately. | 2,000 | 2,200 | 0.5 | 64 HRC | 5.7 % IACS |
What is O2?
O2 (1.2842 / 90MnCrV8, UNS T31502, also 9Mn2V) is a manganese-alloyed oil-hardening cold-work tool steel, close to O1 but with higher manganese for greater hardenability from a low austenitizing temperature. It is bought as annealed or cold-drawn flat and round stock — 420 MPa yield, 740 MPa tensile, 25 % elongation, 205 HB (94 HRB) — for punches, blanking dies and gauges that must hold size, since oil hardening gives 60–62 HRC with only ~0.02 % dimensional change. It has essentially no corrosion resistance and is limited to about 300 °C service; A2 or D2 are better where abrasive wear or air hardening is preferred. O2 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). O2 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
What is O2 used for?
- Blanking and piercing dies
- Punches
- Shear and trim blades
- Gauges and templates
- Thread-rolling and knurling tools
- Woodworking knives
- Engraving and embossing tools
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
O2 properties
Typical room-temperature values for O2-Annealed; bars are the position among steel grades.
Physical3
O2 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
O2 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
O2 is rated for continuous service to 300°C (572 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 80% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
O2 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of O2 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 35%.
Manufacturability6
O2's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (15/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. O2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with O2
Is O2 easy to machine?
Machine only in the annealed state with sharp HSS or coated carbide, moderate speeds and rigid setups; after hardening only grinding or EDM is practical.
Can O2 be welded?
Not recommended for structural joints; repair-weld with matching tool-steel filler at 300–400 °C preheat and temper immediately afterwards.
Can O2 be formed, bent or molded?
Hot work at 900–1050 °C with slow cooling; cold forming is limited — harden from 790–815 °C, oil quench (small sections may be air-cooled) and temper at 150–200 °C for 60–62 HRC, expecting only ~0.02 % size change.
Manufacturability
The process limits FabDigit applies to O2. Every O2 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better48 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
O2 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 |
|---|---|---|
| C | 0.85 – 0.95 | 0.9 |
| MnDIN 1.2842 / 90MnCrV8 uses Mn 1.80–2.20 | 1.4 – 1.8 | 1.6 |
| Si | 0.1 – 0.5 | 0.25 |
| Cr1.2842: 0.20–0.50 | 0 – 0.5 | 0.3 |
| V1.2842: 0.05–0.20 | 0 – 0.3 | 0.1 |
| Mo | 0 – 0.3 | |
| W | 0 – 0.3 | |
| Ni | 0 – 0.3 | |
| P | 0 – 0.03 | |
| S | 0 – 0.03 | |
| Fe | balance |
What surface finishes work on O2?
Takes a fine polish for die faces; protect with oil, black oxide, phosphate or thin nitride/PVD coatings since the alloy has essentially no corrosion resistance.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel O2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does O2 cost?
O2 is a premium-cost steel ($$$), pricier than about 57% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
O2 — frequently asked
What is O2 used for?
O2 is typically used for blanking and piercing dies, punches, shear and trim blades, gauges and templates, thread-rolling and knurling tools and woodworking knives. In short: oil-hardening tool steel.
What is the yield strength of O2?
O2 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 740 MPa (107 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is O2 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machine only in the annealed state with sharp HSS or coated carbide, moderate speeds and rigid setups; after hardening only grinding or EDM is practical.
Can O2 be welded?
Not readily — weldability is rated poor (15/100). Not recommended for structural joints; repair-weld with matching tool-steel filler at 300–400 °C preheat and temper immediately afterwards.
What surface finishes work on O2?
Takes a fine polish for die faces; protect with oil, black oxide, phosphate or thin nitride/PVD coatings since the alloy has essentially no corrosion resistance.
Can O2 be formed, bent or molded?
Hot work at 900–1050 °C with slow cooling; cold forming is limited — harden from 790–815 °C, oil quench (small sections may be air-cooled) and temper at 150–200 °C for 60–62 HRC, expecting only ~0.02 % size change.
What is the maximum service temperature of O2?
O2 is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does O2 cost?
O2 is a premium-cost steel ($$$), pricier than about 57% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in O2?
Yes — O2 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A681 — Alloy Tool Steels — ASTM International (2015)
- EN ISO 4957 — Tool steels (90MnCrV8 / 1.2842) — CEN/ISO (2018)
- GB/T 1299 (9Mn2V) — SAC (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 1.2842 / 90MnCrV8 cold-work tool steel datasheet — European tool-steel producers (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.