Steel 4820 · heat-treated state
Steel 4820 Carburized
Properties of the Carburized condition, compared with the other 4820 tempers.
The primary reason to buy 4820: hard wear-resistant case on a tough, high-nickel core for heavily loaded gears and bearings.
What is 4820 Carburized?
4820 Carburized is 4820 heat treated to Carburized — the primary reason to buy 4820: hard wear-resistant case on a tough, high-nickel core for heavily loaded gears and bearings. 4820 Carburized has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). 4820 Carburized has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 89% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; Carburized is available on request or by drawing note.
Advantages
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 100% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Low electrical conductivity — 6.9 % IACS, worse than 76% of steel grades
4820 Carburized properties
Typical room-temperature values for 4820 Carburized — 12 properties are specific to this condition; the rest are grade-level values shared by every 4820 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
4820 Carburized has a density of 7.86 g/cm³ (0.284 lb/in³), heavier than 89% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical13
4820 Carburized has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4820 Carburized is rated for continuous service to 180°C (356 °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 Carburized 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 Carburized 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 Carburized's machinability is not recommended (10/100, worse than 100% of steel grades); weldability fair (40/100); formability good (55/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 4820 tempers and conditions
4820 is also supplied in 6 other conditions. The full side-by-side table is on the 4820 overview.
- HRDefaultStandard stocked mill condition for bar and billet that will be machined then carburized.450 MPa yield · 200 HB
- CarburizedThe primary reason to buy 4820: hard wear-resistant case on a tough, high-nickel core for heavily loaded gears and bearings.950 MPa yield · 60 HRC
- Q&TThrough-hardened condition for shafts and non-carburized structural parts needing high strength with very good toughness.900 MPa yield · 31 HRC
- CDChoose for close-tolerance, bright-finish bar where extra core strength and better chip control are wanted.655 MPa yield · 225 HB
- CRThin strip form for stamped, carburized parts (shims, thin gears, clutch plates) needing a smooth surface.560 MPa yield · 210 HB
- NormalizedUniform fine-grained structure for forgings and for pre-conditioning before carburizing; better toughness than as-rolled.485 MPa yield · 229 HB
- AnnealedSoftest, most machinable and most dimensionally stable state; usual condition for rough gear blanking before carburizing.465 MPa yield · 197 HB
Working with 4820 Carburized
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.
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.
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 | — |
4820 Carburized — frequently asked
What is 4820 Carburized used for?
4820 Carburized is typically used for gears, bearings and pins. In short: carburizing Ni-Cr-Mo bar.
What is the yield strength of 4820 Carburized?
4820 Carburized has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4820 Carburized easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% 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 Carburized 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 Carburized?
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 Carburized 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 Carburized?
4820 Carburized is rated for continuous use to about 180°C (356 °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.
Can FabDigit make parts in 4820 Carburized?
Yes — 4820 Carburized 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
- 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.