Steel 30CrMo4 +U (Hot rolled)
Finish state
EN 30CrMo4
Cheapest mill condition for parts that will be heat treated by the customer after rough machining.
Values for the +U condition
Other 30CrMo4 tempers and conditions
30CrMo4 is listed in 10 conditions; see the grade overview at 30CrMo4.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Spheroidized carbides for maximum cold formability — chosen for cold-headed fasteners and deep cold extrusion. | 370 | 580 | 27 | 10 HRC | 8.2 % IACS |
Treated for shearability | Hardness held low enough for clean cold shearing of bar into blanks before forging or heading. | 380 | 600 | 25 | 11 HRC | 8.2 % IACS |
Annealed | Softest supply condition (≤229 HB) for heavy machining, cold forming or before final quench and temper. | 400 | 620 | 24 | 190 HB | — |
+UThis page Hot rolled | Cheapest mill condition for parts that will be heat treated by the customer after rough machining. | 440 | 700 | 19 | 18 HRC | 8 % IACS |
Normalized | Uniform fine ferrite-pearlite structure for forgings and weldments where full Q&T strength is not required. | 460 | 720 | 20 | 215 HB | — |
+QT | Large-diameter bar and forgings where limited hardenability reduces core properties to ~700–850 MPa. | 500 | 780 | 17 | 22 HRC | — |
Cold drawn | Bright, close-tolerance bar for automatic machining; higher yield but reduced ductility and residual stress. | 620 | 750 | 12 | 230 HB | — |
+QTDefault Quenched and tempered | Standard stocked condition: best balance of ~900 MPa strength, toughness and machinability for shafts and machine parts. | 660 | 900 | 15 | 28 HRC | — |
+QT | Thin sections that through-harden fully, giving 900–1100 MPa tensile with ≥700 MPa yield. | 780 | 1,000 | 13 | 31 HRC | — |
+QT to 28–32 HRC | Specified for oilfield/pressure and sour-service style parts where a hardness ceiling is contractually required. | 780 | 950 | 16 | 30 HRC | — |
What is 30CrMo4 +U?
30CrMo4 +U is 30CrMo4 supplied in the +U condition — cheapest mill condition for parts that will be heat treated by the customer after rough machining. 30CrMo4 +U has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 50% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi). 30CrMo4 +U 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). +QT is the default condition FabDigit quotes; +U is available on request or by drawing note.
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
30CrMo4 +U properties
Typical room-temperature values for 30CrMo4 +U; 23 are specific to this condition. Other listed values are 30CrMo4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
30CrMo4 +U 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
30CrMo4 +U has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 50% of steel grades. Elongation at break is 19% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
30CrMo4 +U is rated for continuous service to 300°C (572 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
30CrMo4 +U 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 30CrMo4 +U takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability8
30CrMo4 +U's machinability is fair (53/100, better than 53% of steel grades); weldability good (65/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 30CrMo4 +U
Is 30CrMo4 easy to machine?
Machines predictably in +A or +QT up to ~30 HRC with carbide tooling and rigid setups; expect ~55 % of 1212 rates and use positive rake plus good coolant to avoid work-hardened surfaces.
Can 30CrMo4 be welded?
Weldable by TIG/MIG with ER80S-D2 or matching Cr-Mo filler; preheat 150–250 °C for thick sections, keep interpass control and stress-relieve or re-heat-treat afterwards to avoid HAZ martensite cracking.
Can 30CrMo4 be formed, bent or molded?
Cold form only in +A/+AC condition with generous bend radii; hot forge 1100–850 °C and always normalize or re-quench and temper after hot work.
What surface finishes work on 30CrMo4?
No corrosion resistance bare — use zinc or cadmium plating, black oxide, manganese phosphate, nitriding or paint; nitriding gives a hard wear surface without losing core Q&T properties.
30CrMo4 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 | 0.26 – 0.34 | 0.3 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.6 |
| P | ≤ 0.03 | 0.02 |
| Smax; ≤0.035 for standard, lower for +S grades | ≤ 0.04 | 0.02 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Fe | balance | — |
30CrMo4 +U — frequently asked
What is 30CrMo4 +U used for?
30CrMo4 +U is typically used for shafts, bolts, gears and structural components. In short: weldable Cr-Mo steel; 4130 tube frame grade; balanced strength and weldability.
What is the yield strength of 30CrMo4 +U?
30CrMo4 +U has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 50% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 30CrMo4 +U easy to machine?
Reasonably — machinability is rated fair (53/100, better than 53% of steel grades). Machines predictably in +A or +QT up to ~30 HRC with carbide tooling and rigid setups; expect ~55 % of 1212 rates and use positive rake plus good coolant to avoid work-hardened surfaces.
Can 30CrMo4 +U be welded?
Yes — weldability is rated good (65/100). Weldable by TIG/MIG with ER80S-D2 or matching Cr-Mo filler; preheat 150–250 °C for thick sections, keep interpass control and stress-relieve or re-heat-treat afterwards to avoid HAZ martensite cracking.
What surface finishes work on 30CrMo4 +U?
No corrosion resistance bare — use zinc or cadmium plating, black oxide, manganese phosphate, nitriding or paint; nitriding gives a hard wear surface without losing core Q&T properties.
Can 30CrMo4 +U be formed, bent or molded?
Cold form only in +A/+AC condition with generous bend radii; hot forge 1100–850 °C and always normalize or re-quench and temper after hot work.
What is the maximum service temperature of 30CrMo4 +U?
30CrMo4 +U 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.
Sources
- EN 10083-3 Steels for quenching and tempering — Alloy steels — CEN (2006)
- EN 10277 / EN 10278 Bright steel products (cold drawn +C) — CEN (2018)
- GB/T 3077 (30CrMo) — SAC (2015)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 19 — Fatigue and Fracture — ASM International (1996)
- MMPDS-17 (AISI 4130 mechanical property tables) — Battelle/FAA (2022)
- 1.7216 / 30CrMo4 alloy steel datasheet — European long-products mills (e.g. Lucchini/Ovako-type) (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.