Steel 4130
AISI/SAE 4130 · UNS G41300 · EN 1.7218, 25CrMo4 · JIS SCM430 · GB 30CrMo
4130 is a low-alloy chromium-molybdenum through-hardening steel (nominally 0.30 C – 1 Cr – 0.2 Mo) supplied as bar, plate, sheet and seamless tube; it is the classic 'chrome-moly' used for aircraft tube frames, roll cages, high-pressure cylinders, drill collars and machine shafts.
Values for the HR condition
4130 tempers and conditions
4130 is supplied in 12 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full anneal ~845–870 °C, slow cool | Softest and most machinable/formable condition; use for deep machining, cold bending or as the starting point before hardening. | 361 | 560 | 28 | 156 HB | 43 W/m·K |
HRDefault Hot rolled | Cheapest mill condition for bar and plate that will be heat treated or machined afterwards; scaled surface and variable properties. | 440 | 700 | 22 | 210 HB | — |
870–900 °C, air cooled (4130N) | Default stock condition for aircraft-quality 4130 sheet and seamless tube: uniform fine grain, good toughness and weldability at ~730 MPa. | 460 | 731 | 25 | 217 HB | — |
Normalized and tempered | Normalized then high-temper for lower hardness and better dimensional stability/toughness in welded or machined structures. | 500 | 670 | 26 | 13 HRC | 7.7 % IACS |
Cold drawn | Choose for straight, on-size shafting with good surface finish where no further heat treatment is planned. | 600 | 700 | 18 | 17 HRC | 43 W/m·K |
Cold rolled | Thin strip and sheet with tight thickness tolerance and smooth surface; strength raised and ductility cut by the cold reduction. | 690 | 810 | 12 | 22 HRC | 7.7 % IACS |
High-temper | Pick when hardness must stay ≤22–26 HRC for H₂S/sour service or maximum ductility in a hardened part. | 700 | 810 | 22 | 24 HRC | — |
Quenched and tempered | General-purpose hardened condition for shafts, fittings and pressure parts needing ~1000 MPa with retained toughness. | 910 | 1,030 | 18 | 31 HRC | — |
Tempered ~540 °C | Most common ordered hardness band for machined 4130 shafts, flanges and hydraulic bodies. | 910 | 1,030 | 18 | 30 HRC | — |
Tempered ~480 °C | Higher-strength band (~1150 MPa) for gears, sprockets and highly loaded fasteners where some toughness is still needed. | 1,040 | 1,150 | 16 | 34 HRC | — |
Tempered ~400 °C | Use for wear-loaded pins, tooling and drill components; toughness and weldability drop sharply at this hardness. | 1,150 | 1,280 | 14 | 42 HRC | — |
Oil/water quenched, tempered 205 °C | Maximum-strength condition (~1550 MPa) for small highly stressed parts; brittle, notch- and hydrogen-sensitive, not for welding. | 1,340 | 1,550 | 11 | 48 HRC | — |
What is 4130?
4130 is a low-alloy chromium-molybdenum through-hardening steel (nominally 0.30 C – 1 Cr – 0.2 Mo) supplied as bar, plate, sheet and seamless tube; it is the classic 'chrome-moly' used for aircraft tube frames, roll cages, high-pressure cylinders, drill collars and machine shafts. Its attraction is a good strength-to-cost ratio, excellent hardenability in thin sections and unusually good weldability for a heat-treatable alloy steel, with strengths from ~560 MPa annealed to over 1500 MPa quenched-and-tempered. Limits are poor corrosion resistance (must be painted, plated or oiled), risk of hydrogen embrittlement and quench cracking above ~1200 MPa, and the need for preheat/post-weld stress relief in thicker weldments. 4130 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,432°C (2,610 °F). 4130 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 22% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4130 used for?
- Roll cages and tube space frames
- Aircraft engine mounts
- High-pressure gas cylinders
- Drill collars and downhole tools
- Machine shafts and spindles
- Hydraulic cylinder rods
- Motorsport suspension links
- Landing-gear fittings
4130 properties
Typical room-temperature values for 4130-HR; bars are the position among steel grades.
Physical3
4130 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,432°C (2,610 °F).
Mechanical16
4130 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 22% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4130 is rated for continuous service to 400°C (752 °F). It conducts heat at 42.7 W/m·K (24.7 BTU/hr·ft·°F), better than 50% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
4130 conducts electricity at 7.7 % IACS, worse than 65% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of 4130 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
4130's machinability is good (55/100, better than 62% of steel grades); weldability good (65/100); 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. 4130 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4130
Is 4130 easy to machine?
Machines best annealed or normalized (~200 HB) with carbide at moderate speed and heavy positive feed; above 32 HRC expect tool wear, so rough before hardening and finish-grind after.
Can 4130 be welded?
Readily TIG/MIG welded with ER80S-D2 or ER70S-2 filler; preheat 150–250 °C for sections over ~3 mm, avoid quench-hard HAZ by slow cooling and stress relieve 590–650 °C, then re-normalize if full properties are required.
Can 4130 be formed, bent or molded?
Cold bend only in annealed/normalized thin sheet and tube with generous radii (≥3t); hot form 850–1150 °C and re-normalize afterwards, hardened material must not be cold formed.
Manufacturability
The process limits FabDigit's quote engine applies to 4130. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better55 / 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 | Better45 / 100 |
|---|---|
| Weldability | Better65 / 100 |
4130 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 30CrMo: 0.26–0.34 | 0.28 – 0.33 | 0.3 |
| Mn | 0.4 – 0.6 | 0.5 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | |
| Smax; 0.025 max for aircraft quality | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4130?
No natural corrosion resistance — specify zinc, cadmium or nickel plate, phosphate-and-oil, black oxide or epoxy paint; bake plated high-strength parts at 190 °C to relieve hydrogen.
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 4130 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 4130 cost?
4130 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.
4130 — frequently asked
What is 4130 used for?
4130 is typically used for roll cages and tube space frames, aircraft engine mounts, high-pressure gas cylinders, drill collars and downhole tools, machine shafts and spindles and hydraulic cylinder rods. In short: tough aerospace chromoly.
What is the yield strength of 4130?
4130 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 12 listed tempers.
Is 4130 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines best annealed or normalized (~200 HB) with carbide at moderate speed and heavy positive feed; above 32 HRC expect tool wear, so rough before hardening and finish-grind after.
Can 4130 be welded?
Yes — weldability is rated good (65/100). Readily TIG/MIG welded with ER80S-D2 or ER70S-2 filler; preheat 150–250 °C for sections over ~3 mm, avoid quench-hard HAZ by slow cooling and stress relieve 590–650 °C, then re-normalize if full properties are required.
What surface finishes work on 4130?
No natural corrosion resistance — specify zinc, cadmium or nickel plate, phosphate-and-oil, black oxide or epoxy paint; bake plated high-strength parts at 190 °C to relieve hydrogen.
Can 4130 be formed, bent or molded?
Cold bend only in annealed/normalized thin sheet and tube with generous radii (≥3t); hot form 850–1150 °C and re-normalize afterwards, hardened material must not be cold formed.
What is the maximum service temperature of 4130?
4130 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 4130-HR and 4130-CR?
HR is the default condition — cheapest mill condition for bar and plate that will be heat treated or machined afterwards; scaled surface and variable properties. CR: thin strip and sheet with tight thickness tolerance and smooth surface; strength raised and ductility cut by the cold reduction. Yield strength is 440 MPa in HR versus 690 MPa in CR.
How much does 4130 cost?
4130 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 4130?
Yes — 4130 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
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM International (2020)
- ASTM A519 — Seamless Carbon and Alloy Steel Mechanical Tubing — ASTM International (2022)
- AMS 6345 / AMS 6360 — 4130 sheet, plate and tubing (normalized) — SAE International (2019)
- GB/T 3077 — (30CrMo) (2015)
- EN 10083-3 — Quenched and tempered steels, 25CrMo4 (1.7218) — CEN (2006)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- MMPDS-17 Metallic Materials Properties Development and Standardization — Battelle/FAA (2022)
- Atlas of Stress-Strain Curves / ASM Fatigue Data Book — ASM International (2002)
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.