Steel 12CrMo
GB 12CrMo · ASTM A335 Grade P12
12CrMo is a 1Cr-0.5Mo creep-resistant low-alloy steel for boiler and pressure equipment, comparable to ASTM A335 Grade P12.
Reference datasheet — 12CrMo is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the N+T condition
12CrMo tempers and conditions
12CrMo is supplied in 6 conditions, soft to hard. N+T is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick for deep machining, cold forming or as an intermediate state before final heat treatment. | 250 | 430 | 30 | 130 HB | — |
Hot rolled | Cheapest mill condition for bar and plate that will be re-heat-treated after machining or forming. | 295 | 490 | 24 | 155 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for boiler tube, pipe, plate and forgings in creep service to ~550 °C. | 305 | 480 | 27 | 145 HB | — |
Normalized | Slightly stronger and harder than N+T; used for plate and forgings where a temper step is added later or where hardness limits are looser. | 335 | 520 | 24 | 160 HB | 7.8 % IACS |
Quenched and tempered | Choose for high-temperature bolting, valve bodies and forgings needing higher yield strength with retained toughness. | 410 | 570 | 21 | 12 HRC | — |
Cold drawn | Bright, dimensionally accurate bar with raised yield strength — for machined fittings and studs, not for creep-critical parts unless re-normalized. | 460 | 570 | 13 | 180 HB | 7.8 % IACS |
Supply forms, finishes and certifications
Ways 12CrMo is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
TUBE-NT | Seamless tube/pipe N+T | Supply form |
What is 12CrMo?
12CrMo is a 1Cr-0.5Mo creep-resistant low-alloy steel for boiler and pressure equipment, comparable to ASTM A335 Grade P12. It is normally used normalized and tempered (N+T) as seamless tube, pipe, plate and headers where service reaches 550 °C, and is also available in A, N, QT, HR and CD conditions; the default condition gives 305 MPa yield, 480 MPa tensile, 27 % elongation and 145 HB (79 HRB). Machinability is rated 58 and weldability 62, but code joints require preheat and 680–720 °C post-weld heat treatment. It offers no corrosion resistance in wet service; 10CrMo9-10 / P22 is the step up for higher temperatures. 12CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). 12CrMo has a yield strength of 305 MPa (44.2 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 84% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi).
What is 12CrMo used for?
- boiler tubes
- pressure vessels
- steam piping
Advantages
- High service temperature — 550°C (1,022 °F), better than 95% of steel grades
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- Ductile — tolerates forming and impact — 27%, better than 86% of steel grades
Limitations
- Low strength — 305 MPa (44.2 ksi), worse than 84% of steel grades
12CrMo properties
Typical room-temperature values for 12CrMo-N+T; bars are the position among steel grades.
Physical3
12CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
12CrMo has a yield strength of 305 MPa (44.2 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 84% of steel grades. Elongation at break is 27% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12CrMo is rated for continuous service to 550°C (1,022 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
12CrMo conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 12CrMo takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
12CrMo's machinability is good (58/100, better than 75% of steel grades); weldability good (62/100); formability good (60/100).
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. 12CrMo is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 12CrMo
Is 12CrMo easy to machine?
Machines like annealed 4130 — rigid setups, carbide inserts at moderate speed, generous coolant; work-hardening is mild but Mo carbides shorten tool life versus plain carbon steel.
Can 12CrMo be welded?
P-No.4 material: preheat 150–250 °C, use matched 1Cr-0.5Mo filler (E8018-B2 / ER80S-B2), keep interpass ≥150 °C and apply 680–720 °C PWHT to soften the HAZ and avoid hydrogen cracking.
Can 12CrMo be formed, bent or molded?
Hot form at 1100–850 °C then re-normalize and temper; cold bending of tube is feasible at generous radii but tight bends should be stress-relieved.
12CrMo 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 |
|---|---|---|
| CGB/T 3077 12CrMo; A335 P12 allows 0.05–0.15 | 0.08 – 0.15 | 0.12 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| CrA335 P12 requires 0.80–1.25 Cr — check the governing standard before substitution | 0.4 – 0.7 | 0.55 |
| Mo | 0.4 – 0.55 | 0.48 |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.2 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 12CrMo?
No anodizing (ferrous) — protect with phosphate plus high-temperature aluminium/silicone paint, aluminising or spray coatings for external oxidation; internal steam side relies on the protective magnetite film.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 12CrMo in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- A335 Grade P12
How much does 12CrMo cost?
12CrMo is a budget-cost steel ($), cheaper than about 90% 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.
12CrMo — frequently asked
What is 12CrMo used for?
12CrMo is typically used for boiler tubes, pressure vessels and steam piping. In short: creep-resistant 1Cr-0.5Mo steel; A335 P12 equivalent; service to 550 °C.
What is the yield strength of 12CrMo?
12CrMo has a typical yield strength of 305 MPa (44.2 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 84% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 12CrMo easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like annealed 4130 — rigid setups, carbide inserts at moderate speed, generous coolant; work-hardening is mild but Mo carbides shorten tool life versus plain carbon steel.
Can 12CrMo be welded?
Yes — weldability is rated good (62/100). P-No.4 material: preheat 150–250 °C, use matched 1Cr-0.5Mo filler (E8018-B2 / ER80S-B2), keep interpass ≥150 °C and apply 680–720 °C PWHT to soften the HAZ and avoid hydrogen cracking.
What surface finishes work on 12CrMo?
No anodizing (ferrous) — protect with phosphate plus high-temperature aluminium/silicone paint, aluminising or spray coatings for external oxidation; internal steam side relies on the protective magnetite film.
Can 12CrMo be formed, bent or molded?
Hot form at 1100–850 °C then re-normalize and temper; cold bending of tube is feasible at generous radii but tight bends should be stress-relieved.
What is the maximum service temperature of 12CrMo?
12CrMo is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 12CrMo N+T and 12CrMo-CD?
N+T is the default condition — standard supply condition for boiler tube, pipe, plate and forgings in creep service to ~550 °C. CD: bright, dimensionally accurate bar with raised yield strength — for machined fittings and studs, not for creep-critical parts unless re-normalized. Yield strength is 305 MPa in N+T versus 460 MPa in CD.
How much does 12CrMo cost?
12CrMo is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- ASTM A335/A335M Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service — ASTM International (2023)
- ASME BPVC Section II Part D — Materials, Properties — ASME (2023)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- API RP 941 — Steels for Hydrogen Service (Nelson curves) — API (2016)
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.