Steel 4024 CARB
Heat-treated state
AISI/SAE 4024 · UNS G40240
CARB = carburized, quenched and tempered
Primary end-use condition: hard wear-resistant case over a tough moderate-strength core for pins, gears and bushings.
Values for the CARB condition
Other 4024 tempers and conditions
4024 is listed in 7 conditions; see the grade overview at 4024.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick when maximum cold formability or the softest structure before deep machining is wanted. | 290 | 450 | 30 | 131 HB | 8 % IACS |
HRDefault Hot rolled | Lowest-cost stock condition for parts that will be machined and then carburized. | 330 | 490 | 25 | 143 HB | — |
Normalized | Uniform fine-grained structure before carburizing; better machined-surface finish than as-rolled. | 370 | 530 | 27 | 156 HB | 7.8 % IACS |
Cold drawn, stress relieved | Use when machining-induced distortion must be minimized on long slender parts. | 450 | 550 | 18 | 166 HB | 7.8 % IACS |
Cold drawn | Choose for close size tolerance, bright finish and higher yield strength on screw-machine parts. | 490 | 580 | 15 | 174 HB | — |
Q&T | Through-hardened option when uniform core strength rather than a hard case is required. | 540 | 700 | 18 | 15 HRC | 7.8 % IACS |
CARBThis page Carburized, quenched and tempered | Primary end-use condition: hard wear-resistant case over a tough moderate-strength core for pins, gears and bushings. | 560 | 800 | 13 | 60 HRC | — |
What is 4024 CARB?
4024 CARB is 4024 heat treated to CARB — primary end-use condition: hard wear-resistant case over a tough moderate-strength core for pins, gears and bushings. 4024 CARB has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 73% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). 4024 CARB has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR 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 — 18/100, worse than 97% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
4024 CARB properties
Typical room-temperature values for 4024 CARB; 12 are specific to this condition. Other listed values are 4024 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4024 CARB has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical13
4024 CARB has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 73% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4024 CARB is rated for continuous service to 180°C (356 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
4024 CARB conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 4024 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%.
Manufacturability7
4024 CARB's machinability is poor (18/100, worse than 97% of steel grades); weldability fair (35/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4024 CARB
Is 4024 easy to machine?
Excellent for high-volume screw-machine work — MnS inclusions break chips; run 20–30 % higher speed than 4023 with carbide and sulfur-bearing cutting oil.
Can 4024 be welded?
Marginal: the 0.035–0.050 % S promotes hot cracking; if welding is unavoidable use low-hydrogen filler, 150–200 °C preheat and post-weld stress relief, or specify 4023 instead.
Can 4024 be formed, bent or molded?
Good longitudinal cold heading/bending in the annealed state, but keep bend axes across the rolling direction — transverse ductility is reduced by sulfide stringers.
What surface finishes work on 4024?
Not anodizable; protect with zinc or nickel plating, black oxide or phosphate-and-oil. Sulfide pull-out limits mirror polishing and can leave micro-pits in plated surfaces.
4024 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 |
| Sintentional resulfurizing for free machining | 0.04 – 0.05 | 0.04 |
| P | ≤ 0.04 | — |
| Fe | balance | — |
4024 CARB — frequently asked
What is 4024 CARB used for?
4024 CARB is typically used for automatic screw-machine parts, shafts and fittings. In short: free-machining 4023 variant; best-machining moly steel; high-volume turning grade.
What is the yield strength of 4024 CARB?
4024 CARB has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 4024 CARB easy to machine?
Not especially — machinability is rated poor (18/100, worse than 97% of steel grades). Excellent for high-volume screw-machine work — MnS inclusions break chips; run 20–30 % higher speed than 4023 with carbide and sulfur-bearing cutting oil.
Can 4024 CARB be welded?
With care — weldability is rated fair (35/100). Marginal: the 0.035–0.050 % S promotes hot cracking; if welding is unavoidable use low-hydrogen filler, 150–200 °C preheat and post-weld stress relief, or specify 4023 instead.
What surface finishes work on 4024 CARB?
Not anodizable; protect with zinc or nickel plating, black oxide or phosphate-and-oil. Sulfide pull-out limits mirror polishing and can leave micro-pits in plated surfaces.
Can 4024 CARB be formed, bent or molded?
Good longitudinal cold heading/bending in the annealed state, but keep bend axes across the rolling direction — transverse ductility is reduced by sulfide stringers.
What is the maximum service temperature of 4024 CARB?
4024 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 4024-HR and 4024 CARB?
HR is the default condition — lowest-cost stock condition for parts that will be machined and then carburized. CARB: primary end-use condition: hard wear-resistant case over a tough moderate-strength core for pins, gears and bushings. Yield strength is 330 MPa in HR versus 560 MPa in CARB.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 / ASTM A29-A29M Alloy Steel Bars — ASTM International (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 low-alloy steels) — ASM International (1991)
- Machinery's Handbook, machinability ratings for resulfurized alloy steels — 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.