Steel SCM422 Carburized
Heat-treated state
JIS SCM422
The intended service condition: hard wear-resistant case over a tough, Mo-strengthened core for gears and splined shafts.
Values for the Carburized condition
Other SCM422 tempers and conditions
SCM422 is listed in 8 conditions; see the grade overview at SCM422.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
for cold forming / heading | Choose when the part is cold-headed, cold-extruded or deep-machined before carburizing. | 340 | 540 | 28 | 155 HB | 8 % IACS |
AnnealedDefault full/soft anneal, as-supplied bar | Standard stock condition for carburizing-grade bar: softest and most machinable state before case hardening. | 370 | 580 | 25 | 170 HB | — |
as-rolled black bar | Cheapest raw form; use when the part is fully machined and heat treated afterwards. | 420 | 660 | 20 | 195 HB | 8 % IACS |
880–920 °C air cool | Used to refine grain and homogenize forgings before carburizing or machining. | 470 | 720 | 20 | 210 HB | 8 % IACS |
bright bar, annealed then drawn | Pick for close-tolerance bright bar going straight onto a lathe or screw machine. | 600 | 730 | 12 | 215 HB | 8 % IACS |
Quenched & tempered | Direct-hardened (non-carburized) use for shafts and fasteners needing uniform medium strength and good toughness. | 830 | 1,000 | 15 | 31 HRC | — |
CarburizedThis page case 58–62 HRC | The intended service condition: hard wear-resistant case over a tough, Mo-strengthened core for gears and splined shafts. | 1,000 | 1,200 | 13 | 60 HRC | — |
Quenched & low-tempered | Higher-strength direct-hardened option for medium sections where toughness can be traded for strength. | 1,080 | 1,250 | 12 | 40 HRC | — |
What is SCM422 Carburized?
SCM422 Carburized is SCM422 heat treated to Carburized — the intended service condition: hard wear-resistant case over a tough, Mo-strengthened core for gears and splined shafts. SCM422 Carburized has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Elongation at break is 13% and the elastic modulus is 206 GPa (29.9 Msi). SCM422 Carburized 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). Annealed is the default condition FabDigit quotes; Carburized is available on request or by drawing note.
Advantages
- High strength — 1,000 MPa (145 ksi), better than 92% of steel grades
Limitations
- Difficult to machine — 10/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
SCM422 Carburized properties
Typical room-temperature values for SCM422 Carburized; 12 are specific to this condition. Other listed values are SCM422 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SCM422 Carburized 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
SCM422 Carburized has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Elongation at break is 13% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SCM422 Carburized 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
SCM422 Carburized conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of SCM422 Carburized takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
SCM422 Carburized's machinability is not recommended (10/100, worse than 99% of steel grades); weldability fair (40/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SCM422 Carburized
Is SCM422 easy to machine?
Machine in the annealed or spheroidized state with coated carbide, ~120–180 m/min; leave grinding stock because carburizing causes 0.1–0.3 % growth and distortion.
Can SCM422 be welded?
Poor weldability (CE ≈ 0.7–0.8): preheat 250–350 °C, low-hydrogen filler, and temper/stress relieve immediately; never weld a carburized case.
Can SCM422 be formed, bent or molded?
Hot forge 1150–900 °C then normalize; cold heading only from spheroidize-annealed stock with generous radii.
What surface finishes work on SCM422?
No corrosion resistance bare — use black oxide, manganese phosphate, zinc plating (bake to avoid hydrogen embrittlement) or oil; case-hardened surfaces grind and polish to a fine finish.
SCM422 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 | 0.2 – 0.25 | 0.22 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cr | 0.9 – 1.2 | 1.05 |
| Moraised vs SCM420/SCM421 for core hardenability | 0.35 – 0.45 | 0.4 |
| Niresidual max | ≤ 0.25 | — |
| Curesidual max | ≤ 0.3 | — |
| Febalance; confirm exact limits against the governing mill/JIS Cr-Mo specification for this designation | balance | — |
SCM422 Carburized — frequently asked
What is SCM422 Carburized used for?
SCM422 Carburized is typically used for carburized gears, shafts and pinions. In short: deeper-hardening carburizing Cr-Mo; hard case, strong core; medium-section gear steel.
What is the yield strength of SCM422 Carburized?
SCM422 Carburized has a typical yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 92% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is SCM422 Carburized easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 99% of steel grades). Machine in the annealed or spheroidized state with coated carbide, ~120–180 m/min; leave grinding stock because carburizing causes 0.1–0.3 % growth and distortion.
Can SCM422 Carburized be welded?
With care — weldability is rated fair (40/100). Poor weldability (CE ≈ 0.7–0.8): preheat 250–350 °C, low-hydrogen filler, and temper/stress relieve immediately; never weld a carburized case.
What surface finishes work on SCM422 Carburized?
No corrosion resistance bare — use black oxide, manganese phosphate, zinc plating (bake to avoid hydrogen embrittlement) or oil; case-hardened surfaces grind and polish to a fine finish.
Can SCM422 Carburized be formed, bent or molded?
Hot forge 1150–900 °C then normalize; cold heading only from spheroidize-annealed stock with generous radii.
What is the maximum service temperature of SCM422 Carburized?
SCM422 Carburized 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.
Sources
- JIS G 4053 Low-alloyed steels for machine structural use (Cr-Mo SCM series) — JSA (2016)
- JIS G 4051 / G 0557 carburized case-depth and hardness test practice — JSA (2016)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A: Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- ASM Machining Data Handbook (4100-series machinability) — ASM International (1980)
- GB/T 3077 (equivalent 20CrMo/22CrMo class) — SAC (2015)
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.