Steel 18Cr2Ni4WA CARB
Heat-treated state
GB 18Cr2Ni4WA
CARB = carburized, hardened + 160–180 °C temper
Specify carburizing, hardening and a 160–180 °C temper as the in-service state for gears and splines: a 60 HRC wear case over a tough core gives the highest contact and bending fatigue life.
Values for the CARB condition
Other 18Cr2Ni4WA tempers and conditions
18Cr2Ni4WA is listed in 7 conditions; see the grade overview at 18Cr2Ni4WA.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick the 650–670 °C softening anneal, the usual bar delivery state, for rough machining and gear-blank hobbing, with hardness limited to ≤269 HB per GB/T 3077. | 640 | 850 | 18 | 24 HRC | — |
Cold drawn | Use annealed then cold-drawn bar for small-diameter precision stock with good dimensional accuracy and surface finish; final heat treatment is still needed after machining. | 800 | 950 | 10 | 29 HRC | 5.5 % IACS |
Hot rolled | Use only as the incoming rolled or as-forged blank; hardness is high and uneven at about 350 HB, so anneal it before any machining or forming operation. | 850 | 1,150 | 12 | 38 HRC | 5.5 % IACS |
Quenched + high temper | Choose quenching with a 500–600 °C temper for heavily loaded shafts and flanges that need more ductility and machinability, accepting 1050 MPa instead of low-temper strength. | 900 | 1,050 | 16 | 34 HRC | — |
Normalized | Choose normalizing at 900–950 °C with air cooling to refine post-forging structure; air hardening leaves about 370 HB, so a high temper must follow before machining. | 950 | 1,200 | 12 | 39 HRC | 5.5 % IACS |
CARBThis page Carburized, hardened + 160–180 °C temper | Specify carburizing, hardening and a 160–180 °C temper as the in-service state for gears and splines: a 60 HRC wear case over a tough core gives the highest contact and bending fatigue life. | 1,050 | 1,250 | 12 | 60 HRC | — |
QT200Default Quenched + low temper 200 °C | Pick the property-acceptance route — 950 °C air cool, 850 °C oil quench, 200 °C temper — for uncarburized high-strength shafts, pins and joints needing the best strength-toughness balance. | 1,150 | 1,350 | 13 | 43 HRC | — |
What is 18Cr2Ni4WA CARB?
18Cr2Ni4WA CARB is 18Cr2Ni4WA heat treated to CARB — specify carburizing, hardening and a 160–180 °C temper as the in-service state for gears and splines: a 60 HRC wear case over a tough core gives the highest contact and bending fatigue life. 18Cr2Ni4WA CARB has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). 18Cr2Ni4WA 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). QT200 is the default condition FabDigit quotes; CARB is available on request or by drawing note.
Advantages
- High strength — 1,050 MPa (152 ksi), better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- High embodied carbon — 2.8 kg CO₂/kg, worse than 90% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
18Cr2Ni4WA CARB properties
Typical room-temperature values for 18Cr2Ni4WA CARB; 11 are specific to this condition. Other listed values are 18Cr2Ni4WA reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
18Cr2Ni4WA 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).
Mechanical16
18Cr2Ni4WA CARB has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18Cr2Ni4WA CARB is rated for continuous service to 150°C (302 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
18Cr2Ni4WA CARB conducts electricity at 5.5 % IACS, worse than 81% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of 18Cr2Ni4WA CARB takes about 36 MJ of energy and emits 2.8 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 25%.
Manufacturability7
18Cr2Ni4WA CARB's machinability is not recommended (8/100, worse than 100% of steel grades); weldability poor (20/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 18Cr2Ni4WA CARB
Is 18Cr2Ni4WA easy to machine?
Machine in the annealed (high-temperature tempered) condition with hardness held to ≤269 HB; use rigid setups and carbide tooling at low speed with heavy feed. After quenching or carburizing only grinding and gear honing are practical.
Can 18Cr2Ni4WA be welded?
Poor weldability: high carbon equivalent and air-hardening behaviour require 250–350 °C preheat, a low-hydrogen process and immediate post-weld tempering. Critical transmission parts are normally designed without welds.
Can 18Cr2Ni4WA be formed, bent or molded?
Start forging at 1150–1180 °C, finish at or above 850 °C and cool slowly to avoid flake (white-spot) cracking. Cold forming is effectively impractical; stress relieve and soften fully before heat treatment.
What surface finishes work on 18Cr2Ni4WA?
Shot peening is standard to raise tooth-root fatigue strength, combined with phosphating, black oxide or cadmium / zinc-nickel plating for corrosion protection. In the high-strength condition, bake plated parts at 190–220 °C for 8–24 h to remove hydrogen.
18Cr2Ni4WA 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 | 0.13 – 0.19 | 0.16 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 1.35 – 1.65 | 1.5 |
| Nihigh Ni for hardenability and low-temperature toughness | 4 – 4.5 | 4.25 |
| Wrefines grain, improves tempering stability | 0.8 – 1.2 | 1 |
| Prestricted for class A high-grade quality steel | ≤ 0.03 | — |
| Srestricted for class A high-grade quality steel | ≤ 0.03 | — |
| Curesidual element | ≤ 0.3 | — |
| Fe | balance | — |
18Cr2Ni4WA CARB — frequently asked
What is 18Cr2Ni4WA CARB used for?
18Cr2Ni4WA CARB is typically used for aircraft gears, critical high-load transmission shafts, heavy-duty spur and bevel pinions, splined drive shafts, helicopter and aero gearbox gears and military drivetrain gears. In short: highest-strength carburizing grade; aerospace and military gearing; lowest machinability in family.
What is the yield strength of 18Cr2Ni4WA CARB?
18Cr2Ni4WA CARB has a typical yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 18Cr2Ni4WA CARB easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine in the annealed (high-temperature tempered) condition with hardness held to ≤269 HB; use rigid setups and carbide tooling at low speed with heavy feed. After quenching or carburizing only grinding and gear honing are practical.
Can 18Cr2Ni4WA CARB be welded?
Not readily — weldability is rated poor (20/100). Poor weldability: high carbon equivalent and air-hardening behaviour require 250–350 °C preheat, a low-hydrogen process and immediate post-weld tempering. Critical transmission parts are normally designed without welds.
What surface finishes work on 18Cr2Ni4WA CARB?
Shot peening is standard to raise tooth-root fatigue strength, combined with phosphating, black oxide or cadmium / zinc-nickel plating for corrosion protection. In the high-strength condition, bake plated parts at 190–220 °C for 8–24 h to remove hydrogen.
Can 18Cr2Ni4WA CARB be formed, bent or molded?
Start forging at 1150–1180 °C, finish at or above 850 °C and cool slowly to avoid flake (white-spot) cracking. Cold forming is effectively impractical; stress relieve and soften fully before heat treatment.
What is the maximum service temperature of 18Cr2Ni4WA CARB?
18Cr2Ni4WA CARB is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 18Cr2Ni4WA-QT200 and 18Cr2Ni4WA-A?
QT200 is the default condition — pick the property-acceptance route — 950 °C air cool, 850 °C oil quench, 200 °C temper — for uncarburized high-strength shafts, pins and joints needing the best strength-toughness balance. A: pick the 650–670 °C softening anneal, the usual bar delivery state, for rough machining and gear-blank hobbing, with hardness limited to ≤269 HB per GB/T 3077. Yield strength is 1,150 MPa in QT200 versus 640 MPa in A.
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.