Steel 30CrMo
GB 30CrMo · EN 1.7218, 25CrMo4 · JIS SCM430
30CrMo is a chromium-molybdenum alloy structural steel of the GB alloy-steel family, equivalent to AISI 4130 and 30CrMo4 and normally supplied quenched and tempered.
Values for the HR condition
30CrMo tempers and conditions
30CrMo is supplied in 8 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize anneal ~830–860 °C, slow cool | Softest and most machinable/formable state; choose for deep machining, cold forming or before final quench and temper. | 390 | 620 | 24 | 185 HB | — |
HRDefault Hot rolled | Most stocked mill condition for bar and plate; buy when you will machine and then heat treat the part yourself. | 500 | 800 | 18 | 215 HB | — |
Normalized and tempered | Pick for large sections or welded assemblies where full quench hardening is impractical but stress-free mid strength is wanted. | 520 | 760 | 20 | 18 HRC | 7.8 % IACS |
Cold rolled | Thin-gauge strip and sheet for stamped or roll-formed parts that will be quenched and tempered after forming. | 570 | 720 | 13 | 20 HRC | 7.8 % IACS |
870–900 °C, air cool | Uniform fine-grain structure with mid-range strength; used for weld fabrications and as a pre-treatment before Q&T. | 570 | 830 | 18 | 22 HRC | — |
Cold drawn | Choose for close-tolerance, good-surface bar used as-is in shafts and studs without further heat treatment. | 660 | 790 | 11 | 235 HB | — |
Quenched and tempered to a specified hardness band | Ordered when drawings call out a hardness band for machinability plus fatigue strength (typical for pinions, couplings, hydraulic bodies). | 810 | 950 | 15 | 30 HRC | 7.5 % IACS |
Quenched and tempered | Standard high-strength delivery condition for shafts, bolts and pressure parts; ~930 MPa minimum UTS with high toughness. | 850 | 990 | 14 | 31 HRC | — |
What is 30CrMo?
30CrMo is a chromium-molybdenum alloy structural steel of the GB alloy-steel family, equivalent to AISI 4130 and 30CrMo4 and normally supplied quenched and tempered. In the default Q&T condition it gives about 500 MPa yield, 800 MPa tensile, 18 % elongation and 215 HB with useful strength to roughly 400 °C, which suits shafts, flanges, hydraulic cylinders and pressure parts; bar and tube are available hot-rolled, cold-drawn, annealed, normalized and at 28–32 HRC. It welds only with preheat and post-weld tempering and has no corrosion resistance; 42CrMo (4140) is the usual step up in strength. 30CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 30CrMo has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
What is 30CrMo used for?
- Shafts
- Industrial bolts
- Hydraulic cylinders
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
30CrMo properties
Typical room-temperature values for 30CrMo-HR; bars are the position among steel grades.
Physical3
30CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
30CrMo has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 63% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
30CrMo is rated for continuous service to 400°C (752 °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
30CrMo 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 30CrMo takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
30CrMo's machinability is fair (54/100, better than 54% of steel grades); weldability good (60/100); formability fair (45/100).
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. 30CrMo is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 30CrMo
Is 30CrMo easy to machine?
Machine in the annealed or 28–32 HRC condition with carbide inserts, ~60 % of 1212 rates; above 34 HRC expect rapid tool wear and prefer grinding.
Can 30CrMo be welded?
Weldable by TIG/MIG/SMAW with ER80S-D2/E8018-B2 filler; preheat 150–250 °C and temper/stress relieve at 600–650 °C to avoid hydrogen and quench cracks.
Can 30CrMo be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed state with generous radii.
Manufacturability
The process limits FabDigit applies to 30CrMo. Every 30CrMo part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better54 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair45 / 100 |
|---|---|
| Weldability | Better60 / 100 |
30CrMo 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 3077-2015 | 0.26 – 0.34 | 0.3 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.4 – 0.7 | 0.55 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.25 | |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 30CrMo?
No natural corrosion protection — use phosphate + oil, black oxide, zinc or hard-chrome plating, or paint; polishes and nitrides well after Q&T.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 30CrMo in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 30CrMo cost?
30CrMo is a standard-cost steel ($$), cheaper than about 71% 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.
30CrMo — frequently asked
What is 30CrMo used for?
30CrMo is typically used for shafts, industrial bolts and hydraulic cylinders. In short: workhorse Cr-Mo bar.
What is the yield strength of 30CrMo?
30CrMo has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 30CrMo easy to machine?
Reasonably — machinability is rated fair (54/100, better than 54% of steel grades). Machine in the annealed or 28–32 HRC condition with carbide inserts, ~60 % of 1212 rates; above 34 HRC expect rapid tool wear and prefer grinding.
Can 30CrMo be welded?
Yes — weldability is rated good (60/100). Weldable by TIG/MIG/SMAW with ER80S-D2/E8018-B2 filler; preheat 150–250 °C and temper/stress relieve at 600–650 °C to avoid hydrogen and quench cracks.
What surface finishes work on 30CrMo?
No natural corrosion protection — use phosphate + oil, black oxide, zinc or hard-chrome plating, or paint; polishes and nitrides well after Q&T.
Can 30CrMo be formed, bent or molded?
Hot forge 1150–850 °C then normalize; cold bending only in the annealed state with generous radii.
What is the maximum service temperature of 30CrMo?
30CrMo 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.
What is the difference between 30CrMo-HR and 30CrMo-CD?
HR is the default condition — most stocked mill condition for bar and plate; buy when you will machine and then heat treat the part yourself. CD: choose for close-tolerance, good-surface bar used as-is in shafts and studs without further heat treatment. Yield strength is 500 MPa in HR versus 660 MPa in CD.
How much does 30CrMo cost?
30CrMo is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in 30CrMo?
Yes — 30CrMo is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10083-3 Steels for quenching and tempering (25CrMo4 / 1.7218) — CEN (2006)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Machinery's Handbook, 31st ed. (machinability and heat-treat data) — Industrial Press (2020)
- 1.7218 / 25CrMo4 alloy steel datasheet — Böhler / Lucefin group data (2020)
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.