Steel 4820 · heat-treated state
Steel 4820 Q&T
Properties of the Q&T condition, compared with the other 4820 tempers.
Through-hardened condition for shafts and non-carburized structural parts needing high strength with very good toughness.
What is 4820 Q&T?
4820 Q&T is 4820 heat treated to Q&T — through-hardened condition for shafts and non-carburized structural parts needing high strength with very good toughness. 4820 Q&T has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). 4820 Q&T 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; Q&T is available on request or by drawing note.
Advantages
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 38/100, worse than 80% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 77% 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 Q&T properties
Typical room-temperature values for 4820 Q&T — 13 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 Q&T 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 Q&T has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4820 Q&T is rated for continuous service to 300°C (572 °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 Q&T 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 Q&T 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 Q&T's machinability is fair (38/100, worse than 80% 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 Q&T
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 Q&T — frequently asked
What is 4820 Q&T used for?
4820 Q&T is typically used for gears, bearings and pins. In short: carburizing Ni-Cr-Mo bar.
What is the yield strength of 4820 Q&T?
4820 Q&T has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,030 MPa (149 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4820 Q&T easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% 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 Q&T 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 Q&T?
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 Q&T 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 Q&T?
4820 Q&T 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.
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 Q&T?
Yes — 4820 Q&T 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.