Case-Hardening Steels / C10-C15
Unalloyed Carbon Case Hardening Steel
Low-carbon, unalloyed case hardening steels. Economical solution for simple geometry and medium-duty parts with lower hardenability. Provides surface hardness and tough core after carburizing.
Technical Specifications
Key Features
- Economical case hardening steel solution
- Hard surface and tough core after carburizing
- Good cold formability
- Excellent machinability
- Good weldability
- Low tendency to internal stresses
- Adequate hardenability in small cross-sections
- Suitable for precision cold drawing
Applications
- Light-duty gears
- Pins and fasteners
- Chain components
- Simple geometry machine parts
- Automotive auxiliary components
- Hydraulic cylinder pins
- Agricultural machinery thin-section parts
- General machine structural elements
Dimension Table
| Profile | Size Range (mm) | Tolerance | Standard Length (m) | Delivery Condition |
|---|---|---|---|---|
| Round | 5 - 20 | h9 | 3 | +AC / +C |
| Round | 20 - 60 | h9, h10 | 3 | +AC / +C |
| Round | 60 - 120 | h10, h11 | 3 | +AC / +C |
| Hexagon | 6 - 30 | h9 | 3 | +C |
| Hexagon | 30 - 70 | h10, h11 | 3 | +C |
| Square | 6 - 30 | h9 | 3 | +C |
| Square | 30 - 70 | h10, h11 | 3 | +C |
Technical Notes
- 01Carburizing temperature: 900-920°C (typical for C10/C15)
- 02Case depth (CHD): Typically 0.3-1.5mm
- 03Post-carburizing heat treatment: Quench (water or salt bath) + temper at 150-180°C
- 04Surface hardness: 55-62 HRC (after carburizing + quenching)
- 05Core hardness: 20-35 HRC (lower hardenability due to unalloyed composition)
- 06Low hardenability: Full hardening only achieved in thin sections (<20mm)
- 07Delivery condition: +AC (annealed) or +C (cold drawn)
- 08C15 offers slightly higher strength and hardenability compared to C10
Other Types
What is case-hardening steel?
Case-hardening steel is a low-carbon steel (0.10–0.25% C) hardened by diffusing carbon into its surface (carburizing). The result is a hard, wear-resistant case (58–62 HRC) with a tough, impact-resistant core. Common grades: 16MnCr5, 20MnCr5, C10/C15 and 18CrNiMo7-6 (EN 10084). Used for gears, shafts, cams and pins.
The carburizing process and grade selection
The part is held at ~880–950°C in a carbon-rich medium (gas, pack or salt bath); carbon diffuses into the surface (typical case depth 0.3–2 mm), followed by quenching and low-temperature tempering. Grade selection depends on section size and load: C10/C15 for small parts, 16MnCr5 for medium sections, 20MnCr5 for higher core strength, and 18CrNiMo7-6 for heavily loaded large gears. Cr and Mn raise hardenability; Ni adds toughness.
Frequently Asked Questions
What hardness does 16MnCr5 reach?+
Typically 58–62 HRC at the surface after carburizing and quenching; the core stays tough at roughly 30–45 HRC.
Case-hardening vs quenched-and-tempered steel?+
Case-hardening steel is low-carbon and gains hardness only at the surface via carburizing; Q&T steel (like 42CrMo4) is medium-carbon and hardens through the section.
How deep is the hardened case?+
Typically 0.3–2 mm (CHD) depending on the application, controlled by time, temperature and carbon potential.
Which parts use case-hardening steel?+
Gears, shafts, camshafts, pins and bearing components — parts that wear at the surface but take impact loads.
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