Steel 12CrMo4 +QT (Quenched and tempered)
Heat-treated state
EN 12CrMo4
Use for bolting, flanges and shafts needing higher yield strength with retained toughness at moderate temperature.
Values for the +QT condition
Other 12CrMo4 tempers and conditions
12CrMo4 is listed in 9 conditions; see the grade overview at 12CrMo4.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Softest condition — pick for cold heading, deep drilling, thread rolling or heavy cold forming before quench-and-temper. | 280 | 460 | 28 | 145 HB | — |
Annealed | General mill-annealed bar/plate condition for machining and subsequent heat treatment. | 300 | 480 | 27 | 150 HB | 7.8 % IACS |
Treated to ferrite-pearlite structure with specified hardness range | Choose when a defined ferrite–pearlite microstructure and hardness band is needed for consistent machining and surface finish before final heat treatment. | 330 | 500 | 24 | 160 HB | 7.8 % IACS |
Normalized and tempered | Preferred for thick-wall pressure parts and weldments where residual stress and hardness must be controlled before service. | 330 | 490 | 25 | 148 HB | 7.8 % IACS |
+NDefault Normalized | Standard supply condition for boiler tube, plate and forgings; balanced strength and toughness for code pressure service. | 340 | 500 | 24 | 150 HB | — |
Hot rolled | Cheapest mill condition for parts that will be fully heat treated after rough machining; properties are section- and cooling-rate dependent. | 340 | 520 | 22 | 165 HB | 7.8 % IACS |
+QTThis page Quenched and tempered | Use for bolting, flanges and shafts needing higher yield strength with retained toughness at moderate temperature. | 480 | 650 | 19 | 15 HRC | — |
Cold drawn | Cold-drawn bar for close tolerance and better surface finish; higher strength but lower ductility and residual stress present. | 520 | 620 | 12 | 195 HB | 7.7 % IACS |
Supplied with specified hardenability (Jominy band), hardened response | Order this when the part will be hardened after machining and a guaranteed Jominy hardenability band / as-hardened hardness is required. | 540 | 720 | 17 | 20 HRC | — |
What is 12CrMo4 +QT?
12CrMo4 +QT is 12CrMo4 heat treated to +QT — use for bolting, flanges and shafts needing higher yield strength with retained toughness at moderate temperature. 12CrMo4 +QT has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 59% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi). 12CrMo4 +QT 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). +N is the default condition FabDigit quotes; +QT is available on request or by drawing note.
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
12CrMo4 +QT properties
Typical room-temperature values for 12CrMo4 +QT; 10 are specific to this condition. Other listed values are 12CrMo4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
12CrMo4 +QT 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
12CrMo4 +QT has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 59% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
12CrMo4 +QT is rated for continuous service to 500°C (932 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
12CrMo4 +QT conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 12CrMo4 +QT takes about 29 MJ of energy and emits 2.2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability6
12CrMo4 +QT's machinability is good (58/100, better than 75% of steel grades); weldability very good (70/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 12CrMo4 +QT
Is 12CrMo4 easy to machine?
Machines like a 60 %-of-1212 alloy steel; best in +AC/+FP condition with carbide tooling, rigid setups and generous coolant to avoid built-up edge.
Can 12CrMo4 be welded?
Readily weldable with matching low-alloy (E8018-B2 / ER80S-B2) consumables; preheat 150–250 °C and PWHT 660–700 °C to control hardness and hydrogen cracking.
Can 12CrMo4 be formed, bent or molded?
Hot form at 950–1150 °C; cold bending possible in annealed condition with generous radii, followed by stress relief.
What surface finishes work on 12CrMo4?
Not stainless — protect with paint, zinc or aluminized coating for ambient service; can be nitrided or hard-chrome plated (bake after plating to avoid hydrogen embrittlement).
12CrMo4 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 | 0.08 – 0.18 | 0.13 |
| Si | ≤ 0.35 | 0.25 |
| Mn | 0.4 – 1 | 0.6 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| Cr | 0.7 – 1.15 | 0.95 |
| Mo | 0.4 – 0.6 | 0.5 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
12CrMo4 +QT — frequently asked
What is 12CrMo4 +QT used for?
12CrMo4 +QT is typically used for pressure vessel parts, boiler components, pipe fittings and flanges. In short: weldable creep-resistant steel; 530 °C service ceiling; low-carbon Cr-Mo grade.
What is the yield strength of 12CrMo4 +QT?
12CrMo4 +QT has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 650 MPa (94.3 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 12CrMo4 +QT easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a 60 %-of-1212 alloy steel; best in +AC/+FP condition with carbide tooling, rigid setups and generous coolant to avoid built-up edge.
Can 12CrMo4 +QT be welded?
Yes — weldability is rated very good (70/100). Readily weldable with matching low-alloy (E8018-B2 / ER80S-B2) consumables; preheat 150–250 °C and PWHT 660–700 °C to control hardness and hydrogen cracking.
What surface finishes work on 12CrMo4 +QT?
Not stainless — protect with paint, zinc or aluminized coating for ambient service; can be nitrided or hard-chrome plated (bake after plating to avoid hydrogen embrittlement).
Can 12CrMo4 +QT be formed, bent or molded?
Hot form at 950–1150 °C; cold bending possible in annealed condition with generous radii, followed by stress relief.
What is the maximum service temperature of 12CrMo4 +QT?
12CrMo4 +QT is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10216-2 Seamless steel tubes for pressure purposes — alloy steels with elevated temperature properties — CEN (2020)
- EN 10083-3 Steels for quenching and tempering — alloy steels — CEN (2006)
- EN 10084 Case hardening steels — delivery conditions (+A, +AC, +FP, +H, +S) — CEN (2008)
- EN 10028-2 Flat products for pressure purposes — steels with elevated temperature properties — CEN (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook, machining data for Cr-Mo alloy steels — Industrial Press (2020)
- GB/T 3077 (12CrMo ) — SAC (2015)
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.