Steel 4023 CARB
Heat-treated state
AISI/SAE 4023 · UNS G40230
CARB = carburized, quenched & tempered
The intended service condition: hard wear-resistant case over a tough, moderately strong core for gears and pins.
Values for the CARB condition
Other 4023 tempers and conditions
4023 is listed in 7 conditions; see the grade overview at 4023.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition; choose for heavy cold forming, deep drilling or before carburizing. | 290 | 448 | 28 | 137 HB | — |
Hot rolled | Cheapest bar condition for parts that will be machined and then carburized or heat treated. | 315 | 490 | 25 | 143 HB | — |
Normalized | Uniform fine grain and predictable machining response for forgings before carburizing. | 345 | 520 | 25 | 156 HB | — |
Q&T | Tough medium-strength condition for shafts and small forgings not requiring a hard case. | 450 | 600 | 24 | 179 HB | — |
CDDefault Cold drawn | Most commonly stocked bar: tight tolerance, bright finish, higher yield strength for as-machined parts. | 470 | 552 | 18 | 163 HB | — |
Q&T | Direct hardening of thin sections where a carburized case is not required; limited hardenability above ~25 mm. | 520 | 720 | 17 | 19 HRC | — |
CARBThis page Carburized, quenched & tempered | The intended service condition: hard wear-resistant case over a tough, moderately strong core for gears and pins. | 560 | 780 | 15 | 60 HRC | — |
What is 4023 CARB?
4023 CARB is 4023 heat treated to CARB — the intended service condition: hard wear-resistant case over a tough, moderately strong core for gears and pins. 4023 CARB has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 73% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). 4023 CARB 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). CD is the default condition FabDigit quotes; CARB is available on request or by drawing note.
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
4023 CARB properties
Typical room-temperature values for 4023 CARB; 14 are specific to this condition. Other listed values are 4023 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4023 CARB 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).
Mechanical15
4023 CARB has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 73% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4023 CARB is rated for continuous service to 180°C (356 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
4023 CARB conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4023 CARB takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability6
4023 CARB's machinability is poor (20/100, worse than 97% of steel grades); weldability poor (25/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4023 CARB
Is 4023 easy to machine?
Machines like a soft low-alloy steel (~70 % of 1212); best surface finish in the normalized or cold-drawn condition, use sharp positive-rake carbide and good coolant to avoid built-up edge.
Can 4023 be welded?
Good weldability at 0.2 % C with low Mo; preheat 100–200 °C on thick sections, use low-hydrogen E70XX/ER70S-x consumables, and never weld after carburizing.
Can 4023 be formed, bent or molded?
Cold heads and bends well when annealed; hot forge 1100–1200 °C and normalize afterwards to refine grain before carburizing.
What surface finishes work on 4023?
Not corrosion resistant — specify black oxide, phosphate + oil, zinc or nickel plating; bake after plating to prevent hydrogen embrittlement of hardened cases.
4023 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 |
|---|---|---|
| C | 0.2 – 0.25 | 0.23 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Mo | 0.2 – 0.3 | 0.25 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Fe | balance | — |
4023 CARB — frequently asked
What is 4023 CARB used for?
4023 CARB is typically used for shafts, couplings, connecting rods and gears. In short: weldable 40xx carburizing grade; balanced strength and toughness; common forging stock.
What is the yield strength of 4023 CARB?
4023 CARB has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4023 CARB easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Machines like a soft low-alloy steel (~70 % of 1212); best surface finish in the normalized or cold-drawn condition, use sharp positive-rake carbide and good coolant to avoid built-up edge.
Can 4023 CARB be welded?
Not readily — weldability is rated poor (25/100). Good weldability at 0.2 % C with low Mo; preheat 100–200 °C on thick sections, use low-hydrogen E70XX/ER70S-x consumables, and never weld after carburizing.
What surface finishes work on 4023 CARB?
Not corrosion resistant — specify black oxide, phosphate + oil, zinc or nickel plating; bake after plating to prevent hydrogen embrittlement of hardened cases.
Can 4023 CARB be formed, bent or molded?
Cold heads and bends well when annealed; hot forge 1100–1200 °C and normalize afterwards to refine grain before carburizing.
What is the maximum service temperature of 4023 CARB?
4023 CARB 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 4023-CD and 4023-A?
CD is the default condition — most commonly stocked bar: tight tolerance, bright finish, higher yield strength for as-machined parts. A: softest condition; choose for heavy cold forming, deep drilling or before carburizing. Yield strength is 470 MPa in CD versus 290 MPa in A.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (Carburizing of Alloy Steels) — ASM International (1991)
- Machining Data Handbook — Metcut Research Associates (1980)
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.