Steel 33CrMoV12-9 +U (Hot rolled)
Finish state
EN 33CrMoV12-9
Mill delivery condition for stock that will be fully re-heat-treated by the customer; hard and not suited to direct machining.
Values for the +U condition
Other 33CrMoV12-9 tempers and conditions
33CrMoV12-9 is listed in 5 conditions; see the grade overview at 33CrMoV12-9.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for rough machining, deep-hole drilling or cold work before final quench-and-temper and nitriding. | 500 | 780 | 18 | 230 HB | — |
+UThis page Hot rolled | Mill delivery condition for stock that will be fully re-heat-treated by the customer; hard and not suited to direct machining. | 600 | 950 | 12 | 31 HRC | 5.8 % IACS |
+QT | Same treatment on large forged bars/shafts, where mass effect lowers the guaranteed strength band. | 950 | 1,180 | 12 | 37 HRC | — |
+QTDefault Quenched and tempered | Standard supply and service condition: high core strength and toughness with tempering above the intended nitriding temperature. | 1,050 | 1,300 | 11 | 41 HRC | — |
+QT + gas nitrided | Final functional condition for wear surfaces: very hard nitrided case on a tough Q&T core, with high compressive residual stress boosting fatigue life. | 1,050 | 1,300 | 10 | 67 HRC | — |
What is 33CrMoV12-9 +U?
33CrMoV12-9 +U is 33CrMoV12-9 supplied in the +U condition — mill delivery condition for stock that will be fully re-heat-treated by the customer; hard and not suited to direct machining. 33CrMoV12-9 +U has a yield strength of 600 MPa (87 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 77% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). 33CrMoV12-9 +U has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). +QT is the default condition FabDigit quotes; +U is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- High strength — 600 MPa (87 ksi), better than 77% of steel grades
Limitations
- Difficult to machine — 28/100, worse than 91% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Limited formability — 20/100, worse than 80% of steel grades
- Low electrical conductivity — 5.8 % IACS, worse than 79% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
33CrMoV12-9 +U properties
Typical room-temperature values for 33CrMoV12-9 +U; 22 are specific to this condition. Other listed values are 33CrMoV12-9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
33CrMoV12-9 +U has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
33CrMoV12-9 +U has a yield strength of 600 MPa (87 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 77% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
33CrMoV12-9 +U is rated for continuous service to 400°C (752 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
33CrMoV12-9 +U conducts electricity at 5.8 % IACS, worse than 79% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 33CrMoV12-9 +U takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 35%.
Manufacturability8
33CrMoV12-9 +U's machinability is poor (28/100, worse than 91% of steel grades); weldability poor (25/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 33CrMoV12-9 +U
Is 33CrMoV12-9 easy to machine?
Rough machine in the +AC soft-annealed state; in +QT (≈40 HRC) use coated carbide, rigid setups and low feeds, and leave only grinding stock after nitriding.
Can 33CrMoV12-9 be welded?
Essentially not a weldable structural grade — if repair welding is unavoidable, preheat 300–400 °C, use matching low-hydrogen filler and re-temper below the last tempering temperature.
Can 33CrMoV12-9 be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling, then soft anneal; cold forming is impractical except in the annealed condition at low strain.
What surface finishes work on 33CrMoV12-9?
Gas or plasma nitride at 480–530 °C (always below the tempering temperature) for 800–1000 HV cases; otherwise oil, phosphate, black-oxide or hard chrome since the steel is not stainless.
33CrMoV12-9 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 | 0.29 – 0.36 | 0.33 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| Pimpurity | ≤ 0.03 | — |
| Simpurity; low-S variants for cleanliness | ≤ 0.04 | — |
| Cr | 2.8 – 3.3 | 3.05 |
| Mo | 0.7 – 1.2 | 0.95 |
| V | 0.15 – 0.25 | 0.2 |
| Fe | balance | — |
33CrMoV12-9 +U — frequently asked
What is 33CrMoV12-9 +U used for?
33CrMoV12-9 +U is typically used for high-temperature bearings, aircraft engine components, turbine shafts and high-strength fasteners. In short: hot-strength nitriding steel; hardenable to 41 HRC; effectively non-weldable.
What is the yield strength of 33CrMoV12-9 +U?
33CrMoV12-9 +U has a typical yield strength of 600 MPa (87 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 77% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is 33CrMoV12-9 +U easy to machine?
Not especially — machinability is rated poor (28/100, worse than 91% of steel grades). Rough machine in the +AC soft-annealed state; in +QT (≈40 HRC) use coated carbide, rigid setups and low feeds, and leave only grinding stock after nitriding.
Can 33CrMoV12-9 +U be welded?
Not readily — weldability is rated poor (25/100). Essentially not a weldable structural grade — if repair welding is unavoidable, preheat 300–400 °C, use matching low-hydrogen filler and re-temper below the last tempering temperature.
What surface finishes work on 33CrMoV12-9 +U?
Gas or plasma nitride at 480–530 °C (always below the tempering temperature) for 800–1000 HV cases; otherwise oil, phosphate, black-oxide or hard chrome since the steel is not stainless.
Can 33CrMoV12-9 +U be formed, bent or molded?
Hot forge 1100–850 °C with slow cooling, then soft anneal; cold forming is impractical except in the annealed condition at low strain.
What is the maximum service temperature of 33CrMoV12-9 +U?
33CrMoV12-9 +U 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.
Sources
- EN 10085 — Nitriding steels: technical delivery conditions — CEN (2001)
- EN 10250-3 — Open die steel forgings, alloy special steels — CEN (1999)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (nitriding) — ASM International (2013)
- Nitriding steel 1.8522 / 33CrMoV12-9 bar and forging datasheets — European special steel producers (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.