Carbon: S25C runs 0.22–0.28% against S20C’s 0.18–0.23%. S25C gives a little more as-normalized strength and responds marginally better to direct hardening in thin sections.

Grades · Carbon Steel · S25C

S25C

Data verified

S25C is the JIS G4051 carbon steel at 0.25% carbon — the Japanese designation matching AISI 1025. It sits between the mild steels and the heat-treatable medium-carbon grades: weldable and formable, with modest strength in the normalized condition.

DINC25 (1.0406, near)

AISI1025

JISS25C (JIS G4051)

CategoryCarbon Steel

Chemical composition

Element	Content (%)
C	0.22–0.28
Si	0.15–0.35
Mn	0.30–0.60
P	≤0.030
S	≤0.035

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

Properties

Tensile strength	≥440 MPa (normalized, JIS reference)
Density	7.85 g/cm³
Weldability	Good

Heat treatment

Normalize 860–890 °C; used normalized or annealed, or case carburized for wear surfaces.

Equivalent grades

Standard	Designation
din	C25 (1.0406, near)
aisi	1025
jis	S25C (JIS G4051)
gb	25

Compare side by side: S25C vs 1025

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

Applications & Processing

Applications: Low-load shafts, pins, bolts, keys, spacers and general machine parts in Asian supply chains.

Processing: Machines and welds easily; limited hardenability, so through-hardening is not practical — carburize if a hard case is needed.

FAQ

S25C vs S20C?: Carbon: S25C runs 0.22–0.28% against S20C’s 0.18–0.23%. S25C gives a little more as-normalized strength and responds marginally better to direct hardening in thin sections.

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Source: JIS G4051 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.