S50C Medium Carbon Steel: Composition, Properties & 1050 / C50 Equivalent
S50C is a JIS G 4051 medium carbon steel for machine structural use, with carbon 0.47–0.53%, equivalent to AISI/SAE 1050, EN C50E, and GB Grade 50. It offers higher strength and wear resistance than S45C (reference HB 212–277 after Q+T) and is common in shafts, cams, ratchets, and induction-hardened parts that need more hardness.
Overview
S50C is a medium carbon structural steel under JIS G 4051, with carbon 0.47–0.53% — between S45C and S55C. About 0.05% more carbon than S45C gives higher strength, hardness, and wear resistance after quench-and-temper or induction hardening, at the cost of slightly lower machinability, weldability, and toughness. Where S45C is not hard enough but S55C or an alloy steel is more than the part needs, S50C is a common choice.
S50C 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) | 0.47 – 0.53 |
| Si (Silicon) | 0.15 – 0.35 |
| Mn (Manganese) | 0.60 – 0.90 |
| 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 (~800°C, furnace cool) | — | — | — | 159–192 |
| Normalized (810–860°C, air cool) | ≥ 610 | ≥ 365 | ≥ 20 | 179–235 |
| Q+T (quench 810–860°C water + temper 550–650°C) | ≥ 735 | ≥ 540 | ≥ 15 | 212–277 |
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; actual values depend on section size and heat treatment conditions. Q+T also gives reduction of area ≥ 40% and impact value ≥ 69 J/cm². Double Steel can help arrange specific mechanical testing on request.
Heat Treatment
Quench Hardening
S50C is usually quenched from 810–860°C, mainly in water; with more carbon than S45C, as-quenched hardness is higher. Like S45C it contains no Cr or Mo, so hardenability is limited and larger sections are harder to through-harden. For large parts that need uniform hardening across the section, choose an alloy steel such as SCM440.
Quench & Temper (Q+T)
Q+T (quench + high-temperature temper at 550–650°C) is the most common condition for S50C, with reference hardness HB 212–277 — higher than S45C under the same conditions (HB 201–269). Temper immediately after quenching to avoid cracking; S50C is more sensitive to quench cracking than S45C, so take care with complex shapes and sharp corners.
Induction Hardening
Shafts, cams, and gears that need a wear-resistant surface with a tough core can be induction hardened locally, reaching higher surface hardness than S45C (depending on induction conditions). Q+T before induction hardening gives more uniform hardness and structure.
Normalizing
Normalizing (810–860°C, air cool) relieves machining stress and homogenizes the structure as a preparatory treatment before finishing. S50C carbon is too high for carburizing — for carburized parts choose SCM415, SCM420, or a low carbon steel such as 1010.
International Standard Equivalents
| Standard | Equivalent Grade | Correspondence |
|---|---|---|
| JIS (Japan) | S50C (G 4051) | Reference standard |
| AISI/SAE (USA) | 1050 | Equivalent |
| DIN (Germany) | C50 / Ck50 | Equivalent |
| EN (EU) | C50E (1.1206) | Equivalent |
| ISO | C50E (ISO 683-1) | Equivalent |
| GB (China) | 50 (GB/T 699) | Equivalent |
| BS (UK) | 080M50 | Near equivalent |
Composition ranges differ slightly: AISI/SAE 1050 is C 0.48–0.55%, Mn 0.60–0.90%; EN C50E is C 0.47–0.55%, Si ≤ 0.40%, Mn 0.60–0.90%; GB/T 699 Grade 50 is C 0.47–0.55%, Mn 0.50–0.80%. Acceptance of mechanical properties after heat treatment also differs: JIS G 4051 does not specify them, while ISO 683-1 and EN standards set explicit tensile and impact test requirements. Where a specific standard is required, follow the standard named on the drawing.
Typical Applications
Machine Tools
Guideway sliders, locating pins, and other parts that need more wear resistance than S45C, used quenched and tempered or induction hardened.
Machine Components
Cams, ratchets, clutch parts, sprockets, and medium-load gears, where S50C balances hardness and cost.
Automotive & Motorcycle Parts
Medium-load shafts, connecting rods, and crank-type parts, used after Q+T or induction hardening.
Defense & Structural Parts
Vehicle chassis structural parts, mounting bases, and mechanism brackets, providing stable strength and dimensions after Q+T.
Supply Specifications
| Form | Size Range | Source |
|---|---|---|
| Hot-rolled round bar | Ø 13 – 100 mm | Fengxing |
| Hot-rolled round bar | Ø 14 – 130 mm | CSC |
S50C 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
S50C sits between S45C and S55C: harder than S45C, easier to machine than S55C. It suits cost-sensitive machine parts of moderate section that need more strength or wear resistance than S45C.
Machinability, weldability, and toughness come first
S45C is easier to machine and weld, tougher, and more widely stocked; choose it when hardness requirements are moderate.
Higher as-quenched hardness and wear resistance needed
S55C has more carbon for higher quench hardness and wear resistance, common in hand tool forgings and induction-hardened wear parts.
Large sections or uniform through-hardening needed
With Cr and Mo, SCM440 has far better hardenability than S50C and higher, more uniform strength after Q+T.
For technical consultation, sample quotations, or mill certificate review, 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 S50C steel?
- S50C is a JIS G 4051 medium carbon steel for machine structural use, with carbon 0.47–0.53%. It has higher strength and wear resistance than S45C and reaches its working hardness through Q+T or induction hardening.
- Are S50C, 1050, C50, and GB Grade 50 the same?
- S50C (JIS G 4051) is generally regarded as equivalent to AISI/SAE 1050, EN C50E (1.1206), and GB Grade 50, but composition ranges differ slightly: 1050 is C 0.48–0.55%; C50E is C 0.47–0.55%; Grade 50 is C 0.47–0.55%, Mn 0.50–0.80%. Where certification to a standard is required, follow the standard named on the drawing.
- What is the chemical composition of S50C?
- JIS G 4051 specifies C 0.47–0.53%, Si 0.15–0.35%, Mn 0.60–0.90%, 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 S50C?
- It depends on heat treatment (reference values): annealed HB 159–192, normalized HB 179–235, Q+T HB 212–277. Hardness is not guaranteed for hot-rolled delivery.
- S50C or S45C — which should I choose?
- S50C has about 0.05% more carbon, giving higher strength, hardness, and wear resistance after Q+T or induction hardening; S45C machines and welds more easily and is tougher. Choose S50C when the part needs more wear resistance or strength; S45C is enough for general structural parts.
- Can S50C be carburized?
- Not recommended. S50C carbon is too high for carburizing; for case-carburized parts choose SCM415, SCM420, or a low carbon steel such as 1010.
- How do I order S50C from Double Steel?
- S50C is a regularly supplied grade, available made to order, with a mill certificate and heat (cast) analysis certificate available for every lot. Available sizes are listed in the supply specifications on this page. Please inquire about stock and lead time via the inquiry form or LINE customer service.
Or call +886-424078309 or email [email protected]