Steel 4820
AISI/SAE 4820 · UNS G48200
4820 (G48200) is a nickel-molybdenum case-hardening steel with higher nickel content than the common carburizing grades, giving greater core toughness under heavy tooth loading.
Values for the HR condition
4820 tempers and conditions
4820 is supplied in 7 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
HRDefault Hot rolled | Standard stocked mill condition for bar and billet that will be machined then carburized. | 450 | 700 | 20 | 200 HB | 6.9 % IACS |
full anneal ~815 °C, slow cool | Softest, most machinable and most dimensionally stable state; usual condition for rough gear blanking before carburizing. | 465 | 680 | 22 | 197 HB | — |
~900 °C, air cool | Uniform fine-grained structure for forgings and for pre-conditioning before carburizing; better toughness than as-rolled. | 485 | 750 | 24 | 20 HRC | 6.9 % IACS |
Cold rolled | Thin strip form for stamped, carburized parts (shims, thin gears, clutch plates) needing a smooth surface. | 560 | 720 | 14 | 210 HB | 6.9 % IACS |
Cold drawn | Choose for close-tolerance, bright-finish bar where extra core strength and better chip control are wanted. | 655 | 780 | 14 | 225 HB | — |
Quenched and tempered | Through-hardened condition for shafts and non-carburized structural parts needing high strength with very good toughness. | 900 | 1,030 | 17 | 31 HRC | — |
gas carburized, quenched and low-temper (case 58–62 HRC) | The primary reason to buy 4820: hard wear-resistant case on a tough, high-nickel core for heavily loaded gears and bearings. | 950 | 1,200 | 12 | 60 HRC | — |
What is 4820?
4820 (G48200) is a nickel-molybdenum case-hardening steel with higher nickel content than the common carburizing grades, giving greater core toughness under heavy tooth loading. It is specified for gears, bearing components and pins, and is available hot-rolled, cold-rolled, cold-drawn, annealed, normalized, Q&T and carburized; the default condition runs about 450 MPa yield, 700 MPa tensile, 20 % elongation and 200 HB. The nickel raises cost and narrows availability, machinability is around 52, and the steel has no corrosion resistance uncoated. SNCM220/8620 covers lighter-duty gearing at lower cost. 4820 has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,425°C (2,597 °F). 4820 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 52% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4820 used for?
- Gears
- Bearings
- Pins
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
4820 properties
Typical room-temperature values for 4820-HR; bars are the position among steel grades.
Physical3
4820 has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 90% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
4820 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 52% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4820 is rated for continuous service to 250°C (482 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
4820 conducts electricity at 6.9 % IACS, worse than 76% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4820 takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 35%.
Manufacturability6
4820's machinability is fair (52/100, better than 52% of steel grades); weldability fair (40/100); formability good (55/100).
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. 4820 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4820
Is 4820 easy to machine?
Machine in the annealed or normalized state with rigid setups and sharp carbide; the tough Ni-Mo matrix is gummy — use positive rake, generous feed and flood coolant, and finish-grind after carburizing.
Can 4820 be welded?
Weldable only with care: preheat 200–300 °C, low-hydrogen Ni-bearing filler, and post-weld temper/stress relief; avoid welding carburized surfaces entirely.
Can 4820 be formed, bent or molded?
Cold form only in the annealed condition and expect springback; hot forge 1100–1200 °C, finish above 950 °C, then normalize and anneal before machining.
Manufacturability
The process limits FabDigit applies to 4820. Every 4820 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better52 / 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 | Better55 / 100 |
|---|---|
| Weldability | Better40 / 100 |
4820 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 |
|---|---|---|
| Ccarburizing carbon level | 0.18 – 0.23 | 0.2 |
| Mn | 0.5 – 0.7 | 0.6 |
| Si | 0.15 – 0.35 | 0.25 |
| Nigives core toughness and hardenability | 3.25 – 3.75 | 3.5 |
| Mo | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4820?
No native corrosion protection — phosphate + oil, black oxide, zinc/manganese phosphate or nickel plating; case-hardened surfaces polish and hone well but must not be electroplated without hydrogen bake-out.
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 4820 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G48200
How much does 4820 cost?
4820 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.
4820 — frequently asked
What is 4820 used for?
4820 is typically used for gears, bearings and pins. In short: carburizing Ni-Cr-Mo bar.
What is the yield strength of 4820?
4820 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4820 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machine in the annealed or normalized state with rigid setups and sharp carbide; the tough Ni-Mo matrix is gummy — use positive rake, generous feed and flood coolant, and finish-grind after carburizing.
Can 4820 be welded?
With care — weldability is rated fair (40/100). Weldable only with care: preheat 200–300 °C, low-hydrogen Ni-bearing filler, and post-weld temper/stress relief; avoid welding carburized surfaces entirely.
What surface finishes work on 4820?
No native corrosion protection — phosphate + oil, black oxide, zinc/manganese phosphate or nickel plating; case-hardened surfaces polish and hone well but must not be electroplated without hydrogen bake-out.
Can 4820 be formed, bent or molded?
Cold form only in the annealed condition and expect springback; hot forge 1100–1200 °C, finish above 950 °C, then normalize and anneal before machining.
What is the maximum service temperature of 4820?
4820 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4820-HR and 4820-CD?
HR is the default condition — standard stocked mill condition for bar and billet that will be machined then carburized. CD: choose for close-tolerance, bright-finish bar where extra core strength and better chip control are wanted. Yield strength is 450 MPa in HR versus 655 MPa in CD.
How much does 4820 cost?
4820 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 4820?
Yes — 4820 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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASTM A534 — Carburizing Steels for Anti-Friction Bearings — ASTM (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Ni-Mo steels) — ASM International (1991)
- Machinery's Handbook (machinability ratings, AISI 1212 = 100 %) — Industrial Press (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.