Steel 4626 CARB
Heat-treated state
AISI/SAE 4626 · UNS G46260
CARB = carburized, quenched and tempered
Specify carburizing, quenching and tempering for gears, bushings and pins that need a 60 HRC wear- and contact-fatigue-resistant case over a tough core; welding is effectively excluded.
Values for the CARB condition
Other 4626 tempers and conditions
4626 is listed in 9 conditions; see the grade overview at 4626.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Choose the fully annealed, spheroidized state at 156 HB as the softest condition for machining and cold forming, and the usual aerospace bar stock; strength comes only from later quench and temper. | 350 | 540 | 27 | 156 HB | — |
Hot rolled | Pick the lowest-cost as-rolled bar for blanks that will be forged and then fully heat treated; at 187 HB the surface and hardness are uneven, so leave generous machining stock. | 400 | 640 | 22 | 187 HB | 7.8 % IACS |
Normalized | Normalize at 870–900 °C and air cool to refine forging structure and even out properties, either as a pre-treatment before quench and temper or for moderate 420 MPa yield service. | 420 | 660 | 23 | 192 HB | 7.8 % IACS |
Cold drawn | Pick cold-drawn bar for close dimensional tolerance, good surface and 580 MPa yield on pin and shaft parts needing little machining; cold work cuts elongation to 15 % and formability. | 580 | 680 | 15 | 15 HRC | 7.8 % IACS |
oil quenched and high-temperature tempered | Use oil quenching with a high-temperature temper to 28–32 HRC when impact toughness leads, as on large-section pins, connecting rods and shafts, accepting 830 MPa yield instead of peak strength. | 830 | 960 | 18 | 30 HRC | — |
CARBThis page Carburized, quenched and tempered | Specify carburizing, quenching and tempering for gears, bushings and pins that need a 60 HRC wear- and contact-fatigue-resistant case over a tough core; welding is effectively excluded. | 950 | 1,150 | 12 | 60 HRC | — |
Aircraft Quality | Order vacuum-degassed, low-sulphur, ultrasonically inspected bar for fatigue- and fracture-critical parts such as landing-gear pins; mechanical properties follow the quench-and-temper hardness chosen. | 950 | 1,100 | 18 | 35 HRC | 7.5 % IACS |
oil quenched and tempered | Use this balanced oil-quenched and tempered state, 32–36 HRC and 970 MPa yield, as the default delivery hardness for medium-duty landing-gear pins and shafts, with 16 % elongation retained. | 970 | 1,100 | 16 | 34 HRC | — |
oil quenched and low-temperature tempered | Pick the oil quench plus low-temperature temper to 38–42 HRC for highly stressed pins and wear-resistant journals; toughness and hydrogen-embrittlement margin fall, so plate with care. | 1,180 | 1,300 | 13 | 40 HRC | — |
What is 4626 CARB?
4626 CARB is 4626 heat treated to CARB — specify carburizing, quenching and tempering for gears, bushings and pins that need a 60 HRC wear- and contact-fatigue-resistant case over a tough core; welding is effectively excluded. 4626 CARB has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). 4626 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). A is the default condition FabDigit quotes; CARB 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 weld — 10/100, worse than 99% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
4626 CARB properties
Typical room-temperature values for 4626 CARB; 10 are specific to this condition. Other listed values are 4626 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4626 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).
Mechanical14
4626 CARB has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4626 CARB is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
4626 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 4626 CARB takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability7
4626 CARB's machinability is good (60/100, better than 83% of steel grades); weldability not recommended (10/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4626 CARB
Is 4626 easy to machine?
Turn and mill annealed or normalized bar with carbide tooling at roughly 60–65 % of the 1212 rate. Above 35 HRC after quench and temper, reduce cutting speed and use coated inserts; complete finishing operations before heat treatment where possible.
Can 4626 be welded?
Carbon equivalent is high, so weld with 150–260 °C preheat and low-hydrogen consumables, then temper immediately after welding. Carburized parts and high-hardness quenched-and-tempered parts are normally not welded.
Can 4626 be formed, bent or molded?
Warm or hot forge annealed material at 1050–1200 °C; cold formability is limited. Normalize after forging to refine the structure before quench and temper.
What surface finishes work on 4626?
Cadmium, zinc-nickel or hard chrome plating, or phosphate plus paint, are the usual corrosion protection. High-strength parts must be baked at 190 °C for several hours after plating to remove hydrogen; the steel polishes to a mirror finish but must be protected immediately.
4626 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 |
|---|---|---|
| CSAE J404 / UNS G46260 | 0.24 – 0.29 | 0.27 |
| Mn | 0.45 – 0.65 | 0.55 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.7 – 1 | 0.85 |
| Mo | 0.15 – 0.25 | 0.2 |
| Paerospace quality often limited to 0.025 max | ≤ 0.04 | — |
| Saerospace quality often limited to 0.025 max | ≤ 0.04 | — |
| Fe | balance | — |
4626 CARB — frequently asked
What is 4626 CARB used for?
4626 CARB is typically used for landing gear pins, aircraft bolts and high-strength shafts. In short: aircraft-quality Ni-Mo steel; low-sulfur, clean steel practice; higher-carbon 46xx grade.
What is the yield strength of 4626 CARB?
4626 CARB has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 4626 CARB easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Turn and mill annealed or normalized bar with carbide tooling at roughly 60–65 % of the 1212 rate. Above 35 HRC after quench and temper, reduce cutting speed and use coated inserts; complete finishing operations before heat treatment where possible.
Can 4626 CARB be welded?
Not readily — weldability is rated not recommended (10/100). Carbon equivalent is high, so weld with 150–260 °C preheat and low-hydrogen consumables, then temper immediately after welding. Carburized parts and high-hardness quenched-and-tempered parts are normally not welded.
What surface finishes work on 4626 CARB?
Cadmium, zinc-nickel or hard chrome plating, or phosphate plus paint, are the usual corrosion protection. High-strength parts must be baked at 190 °C for several hours after plating to remove hydrogen; the steel polishes to a mirror finish but must be protected immediately.
Can 4626 CARB be formed, bent or molded?
Warm or hot forge annealed material at 1050–1200 °C; cold formability is limited. Normalize after forging to refine the structure before quench and temper.
What is the maximum service temperature of 4626 CARB?
4626 CARB is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4626-A and 4626 CARB?
A is the default condition — choose the fully annealed, spheroidized state at 156 HB as the softest condition for machining and cold forming, and the usual aerospace bar stock; strength comes only from later quench and temper. CARB: specify carburizing, quenching and tempering for gears, bushings and pins that need a 60 HRC wear- and contact-fatigue-resistant case over a tough core; welding is effectively excluded. Yield strength is 350 MPa in A versus 950 MPa in CARB.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Alloy H Steels (4626H) — SAE International (2018)
- ASTM A29/A29M — 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 — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.