S15C Low Carbon Steel: Composition, Properties & 1015 / C15 Equivalent
S15C is a JIS G 4051 low carbon steel for machine structural use, with carbon 0.13–0.18%, equivalent to EN C15E and GB Grade 15, and close to AISI/SAE 1015. It is soft, easy to cold form and weld, and a common carbon steel for carburizing — used in pins, bushings, light-load gears, and cold-forged parts.
Overview
S15C is a low carbon structural steel under JIS G 4051, with carbon 0.13–0.18% — slightly above S10C and below S20C. With this little carbon it cannot be quench hardened to high hardness, but it is easy to cold forge, bend, weld, and machine, and it carburizes well: after carburizing and quenching the surface is wear resistant while the core keeps the toughness of a low carbon steel. Pins, bushings, washers, light-load gears, and chain parts commonly use S15C.
S15C is a regularly supplied grade, available made to order, with a mill certificate and heat (cast) analysis certificate available for every lot and full chemistry and heat number traceability. See supply specifications below for sizes; please inquire for stock and lead time.
Chemical Composition (JIS G 4051)
| Element | Specification (%) |
|---|---|
| C (Carbon) | 0.13 – 0.18 |
| Si (Silicon) | 0.15 – 0.35 |
| Mn (Manganese) | 0.30 – 0.60 |
| P (Phosphorus) | ≤ 0.030 |
| S (Sulfur) | ≤ 0.035 |
| Ni (Nickel) | ≤ 0.20 |
| Cr (Chromium) | ≤ 0.20 |
| Cu (Copper) | ≤ 0.30 |
| Ni + Cr | ≤ 0.35 |
Mechanical Properties After Heat Treatment (Reference)
| Condition | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HB) |
|---|---|---|---|---|
| Annealed (~880°C, furnace cool) | — | — | — | 111–149 |
| Normalized (880–930°C, air cool) | ≥ 370 | ≥ 235 | ≥ 30 | 111–167 |
Reference values commonly used in the Japanese steel industry after heat treatment (former JIS G 4051 reference values, Ø25 mm test piece) — not guaranteed values for hot-rolled delivery. The current JIS G 4051 does not specify mechanical properties after heat treatment. S15C is too low in carbon for quench-and-temper use; surface hardness and core strength after carburizing depend on carburizing conditions and section size.
Heat Treatment
Carburizing
S15C is a common carbon steel for carburizing. Carburize, quench, and low-temperature temper for a wear-resistant surface with a tough core. Carbon steel has low hardenability, so core strength is lower than alloy carburizing steels such as SCM415 and SCM420; choose an alloy carburizing steel for heavy-load gears or larger carburized sections.
Quench Hardening
With only 0.13–0.18% carbon, direct quench hardening has limited effect, and S15C is not used as a quench-and-temper steel. Choose a medium carbon steel such as S45C when Q+T strength is needed.
Annealing & Normalizing
Process annealing between cold forging or multi-pass cold drawing restores ductility. Normalizing homogenizes the hot-rolled structure, improves the machined surface, and is often used before carburizing.
Welding
Low carbon equivalent gives good weldability, usually without preheating. Do not weld on a carburized case.
International Standard Equivalents
| Standard | Equivalent Grade | Correspondence |
|---|---|---|
| JIS (Japan) | S15C (G 4051) | Reference standard |
| AISI/SAE (USA) | 1015 | Near equivalent |
| DIN (Germany) | C15 / Ck15 | Equivalent |
| EN (EU) | C15E (1.1141) | Equivalent |
| GB (China) | 15 (GB/T 699) | Equivalent |
Composition ranges differ slightly: AISI/SAE 1015 is C 0.13–0.18%, Mn 0.30–0.60% (SAE J403 does not specify Si); EN 10084 C15E is C 0.12–0.18%, Mn 0.30–0.60%; GB/T 699 Grade 15 is C 0.12–0.18%, Mn 0.35–0.65%. Where a specific standard is required, follow the standard named on the drawing.
Typical Applications
Machine Components
Pins, bushings, washers, sleeves, and other parts that do not need high strength, plus light-load carburized parts.
Small Carburized Parts
Light-load gears, chain parts, and cam rollers, wear resistant after carburizing and quenching.
Cold-Forged & Cold-Formed Parts
Cold-forged head parts, cold-bent parts, and small structural parts, using its good cold formability.
Hardware & Welded Parts
Welded brackets, mounting bases, and general hardware structural parts.
Supply Specifications
| Form | Size Range | Source |
|---|---|---|
| Hot-rolled round bar | Ø 13 – 100 mm | Fengxing |
| Hot-rolled round bar | Ø 14 – 130 mm | CSC |
S15C is a regularly supplied grade, available made to order; a mill certificate and heat (cast) analysis certificate are available for every lot. Please inquire for sizes outside these ranges, stock, and lead time.
Selection Guide
S15C suits parts made by cold forming, welding, or light-load carburizing. Choose by the main process and load:
US standard specified on the drawing
Same carbon and manganese ranges as S15C; SAE J403 does not specify Si and allows more sulfur.
Slightly higher strength needed
About 0.05% more carbon for slightly higher strength, with slightly lower cold formability.
Carburized parts need high core strength
Cr-Mo carburizing steel with high hardenability for heavy-load gears and shafts.
Part needs Q+T strength
Medium carbon steel that can be quenched and tempered above HB 200 for loaded shafts and structural parts.
For technical consultation or quotations, contact the Double Steel sales team via the inquiry form below or LINE customer service.
Related Grades
For cross-standard composition and mechanical property tables, see the technical reference tables.
FAQ
- What is S15C steel?
- S15C is a JIS G 4051 low carbon steel for machine structural use, with carbon 0.13–0.18%. It is soft, easy to cold form and weld, and often used for carburizing.
- Are S15C, 1015, C15, and GB Grade 15 the same?
- S15C (JIS G 4051) is generally regarded as equivalent to EN C15E (1.1141) and GB Grade 15, and close to AISI/SAE 1015 (same carbon and manganese ranges, but 1015 does not specify Si and allows more sulfur). Composition ranges differ slightly: C15E is C 0.12–0.18%; Grade 15 is C 0.12–0.18%, Mn 0.35–0.65%. Where certification to a standard is required, follow the standard named on the drawing.
- What is the chemical composition of S15C?
- JIS G 4051 specifies C 0.13–0.18%, Si 0.15–0.35%, Mn 0.30–0.60%, P ≤ 0.030%, S ≤ 0.035%, plus Ni ≤ 0.20%, Cr ≤ 0.20%, Cu ≤ 0.30%, Ni+Cr ≤ 0.35%.
- What is the hardness of S15C?
- It depends on heat treatment (reference values): annealed HB 111–149, normalized HB 111–167. Hardness is not guaranteed for hot-rolled delivery; surface hardness after carburizing depends on carburizing conditions.
- Can S15C be carburized?
- Yes, S15C is a common carbon steel for carburizing, but core strength is limited; use SCM415 or SCM420 for heavy-load carburized parts.
- S15C or S20C — which should I choose?
- S20C has about 0.05% more carbon for slightly higher strength; S15C has slightly better cold formability and weldability. Both can be carburized — choose by load and forming method.
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