20CrMo vs 20CrMnTi — which carburizing steel?

Both are GB gear staples. 20CrMnTi is cheaper and very widely stocked in China, but Ti grain control can scatter hardenability; 20CrMo (like SCM420) gives more consistent core strength and better toughness, and is preferred for export and automotive OEM work.

Is 20CrMo the same as SCM420?

Effectively yes for gear work: the windows overlap almost completely (SCM420 runs slightly higher Mn and Cr). Mill certs should still be checked against the ordered standard before substitution.

Grades · Alloy & Engineering Steel · 20CrMo

20CrMo

Data verified

20CrMo is the GB/T 3077 chromium-molybdenum carburizing steel — the molybdenum-bearing counterpart of 20Cr and the Chinese designation closest to JIS SCM420. The Mo addition lifts core hardenability and temper resistance over plain Cr carburizing grades, making it a staple for automotive and motorcycle gears.

DIN18CrMo4 / 1.7243 (near)

AISI4118 (near)

JISSCM420

CategoryAlloy & Engineering Steel

Chemical composition

Element	Content (%)
C	0.17–0.24
Si	0.17–0.37
Mn	0.40–0.70
P	≤0.035
S	≤0.035
Cr	0.80–1.10
Mo	0.15–0.25

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Case hardness (carburized)	58–63 HRC
Tensile strength	≥885 MPa (GB/T 3077 reference, carburized test piece)
Density	7.85 g/cm³

Heat treatment

Carburize 900–930 °C; quench 850–880 °C in oil; temper 150–200 °C. Also used quenched and tempered without carburizing for moderate-duty shafts.

Equivalent grades

Standard	Designation
din	18CrMo4 / 1.7243 (near)
aisi	4118 (near)
jis	SCM420
gb	20CrMo (GB/T 3077)

Compare side by side: 20CrMo vs 4118 · 20CrMo vs SCM420

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Carburized gears, gear shafts, camshafts, piston pins, motorcycle transmission parts, small-to-medium drivetrain components.

Processing: Good machinability before carburizing; grinds well after hardening. Distortion is moderate and predictable with oil quenching.

FAQ

20CrMo vs 20CrMnTi — which carburizing steel?: Both are GB gear staples. 20CrMnTi is cheaper and very widely stocked in China, but Ti grain control can scatter hardenability; 20CrMo (like SCM420) gives more consistent core strength and better toughness, and is preferred for export and automotive OEM work.
Is 20CrMo the same as SCM420?: Effectively yes for gear work: the windows overlap almost completely (SCM420 runs slightly higher Mn and Cr). Mill certs should still be checked against the ordered standard before substitution.

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Source: GB/T 3077 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.