Steel 15CrMo · heat-treated state
Steel 15CrMo N&T
Properties of the N&T condition, compared with the other 15CrMo tempers.
Standard GB/T 3077 and GB 5310 supply condition for boiler tubes, headers and pressure plate — best balance of creep strength, toughness and weld compatibility.
What is 15CrMo N&T?
15CrMo N&T is 15CrMo heat treated to N&T — standard GB/T 3077 and GB 5310 supply condition for boiler tubes, headers and pressure plate — best balance of creep strength, toughness and weld compatibility. 15CrMo N&T has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). 15CrMo N&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; N&T is available on request or by drawing note.
Advantages
- High service temperature — 550°C (1,022 °F), better than 94% 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 — 25%, better than 76% of steel grades
Limitations
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
15CrMo N&T properties
Typical room-temperature values for 15CrMo N&T — 12 properties are specific to this condition; the rest are grade-level values shared by every 15CrMo temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
15CrMo N&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
15CrMo N&T has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
15CrMo N&T 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 12.1 µm/m·K (6.72 µin/in·°F).
Electrical3
15CrMo N&T conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 15CrMo N&T takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 55% of steel grades. Typical recycled content is 30%.
Manufacturability8
15CrMo N&T's machinability is fair (54/100, better than 54% of steel grades); weldability good (62/100); formability good (55/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 15CrMo tempers and conditions
15CrMo is also supplied in 6 other conditions. The full side-by-side table is on the 15CrMo overview.
- HRDefaultMost commonly stocked mill condition for 15CrMo plate, bar and seamless tube before final heat treatment or as-supplied for general pressure work.305 MPa yield · 155 HB
- Q&TChoose for high-temperature bolting, valve stems and shafts where higher yield strength and toughness than N&T are needed below ~500 °C.550 MPa yield · 19 HRC
- CDPick for small-diameter bar needing tight tolerance, bright finish and higher yield strength without heat treatment.500 MPa yield · 185 HB
- NormalizedUse to refine grain and homogenise forgings/plate; higher strength than annealed but usually followed by a temper for pressure service.340 MPa yield · 165 HB
- N&TStandard GB/T 3077 and GB 5310 supply condition for boiler tubes, headers and pressure plate — best balance of creep strength, toughness and weld compatibility.300 MPa yield · 150 HB
- AnnealedPick for maximum machinability and cold formability, or to soften after forging before final normalize-and-temper.265 MPa yield · 145 HB
Working with 15CrMo N&T
Is 15CrMo easy to machine?
Machines like normalized 4130 at ~60 % of 1212; carbide tooling, rigid setups and moderate speeds — anneal or N&T before heavy cuts and expect work hardening in the Q&T condition.
Can 15CrMo be welded?
Weldable with matched E8018-B2 / ER80S-B2 consumables, preheat 150–250 °C, interpass ≤300 °C and PWHT 680–720 °C to soften the martensitic HAZ and restore creep ductility.
Can 15CrMo be formed, bent or molded?
Hot forms readily at 1100–850 °C; cold bending of tube is possible with generous radii, but re-normalize and temper after severe cold work.
What surface finishes work on 15CrMo?
No anodizing; protect with phosphate + high-temperature aluminium paint, aluminizing or thermal insulation, since the alloy rusts freely below the dew point.
15CrMo 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 | 0.12 – 0.18 | 0.15 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.4 – 0.55 | 0.48 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.2 | — |
| Pimpurity | ≤ 0.03 | — |
| Simpurity | ≤ 0.03 | — |
| Fe | balance | — |
15CrMo N&T — frequently asked
What is 15CrMo N&T used for?
15CrMo N&T is typically used for boiler superheater tubes, hot petrochemical piping, steam headers and manifolds, pressure vessel plate for hydrogen service, forged flanges and pipe fittings and elevated-temperature pressure parts. In short: chrome-moly boiler pipe.
What is the yield strength of 15CrMo N&T?
15CrMo N&T has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 490 MPa (71.1 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 15CrMo N&T easy to machine?
Reasonably — machinability is rated fair (54/100, better than 54% of steel grades). Machines like normalized 4130 at ~60 % of 1212; carbide tooling, rigid setups and moderate speeds — anneal or N&T before heavy cuts and expect work hardening in the Q&T condition.
Can 15CrMo N&T be welded?
Yes — weldability is rated good (62/100). Weldable with matched E8018-B2 / ER80S-B2 consumables, preheat 150–250 °C, interpass ≤300 °C and PWHT 680–720 °C to soften the martensitic HAZ and restore creep ductility.
What surface finishes work on 15CrMo N&T?
No anodizing; protect with phosphate + high-temperature aluminium paint, aluminizing or thermal insulation, since the alloy rusts freely below the dew point.
Can 15CrMo N&T be formed, bent or molded?
Hot forms readily at 1100–850 °C; cold bending of tube is possible with generous radii, but re-normalize and temper after severe cold work.
What is the maximum service temperature of 15CrMo N&T?
15CrMo N&T 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 15CrMo-HR and 15CrMo-CD?
HR is the default condition — most commonly stocked mill condition for 15CrMo plate, bar and seamless tube before final heat treatment or as-supplied for general pressure work. CD: pick for small-diameter bar needing tight tolerance, bright finish and higher yield strength without heat treatment. Yield strength is 305 MPa in HR versus 500 MPa in CD.
Can FabDigit make parts in 15CrMo N&T?
Yes — 15CrMo N&T is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 3077 Alloy structural steels (2015)
- GB 5310 Seamless steel tubes for high pressure boilers — SAC (2017)
- ASTM A335/A335M Grade P12 seamless ferritic alloy-steel pipe — ASTM International (2023)
- EN 10216-2 (13CrMo4-5, 1.7335) seamless steel tubes for pressure purposes — CEN (2020)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASME BPVC Section II Part D — physical properties and allowable stresses — ASME (2023)
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.