Case-Hardening Steels / 16MnCr5
Chromium-Manganese Alloyed Case Hardening Steel
Alloyed case hardening steel with high hardenability, providing excellent surface hardness and tough core after carburizing. Industry standard for gears, piston pins, and transmission components.
Technical Specifications
Key Features
- High hardenability (deep case depth achievable)
- Hard, wear-resistant surface after carburizing
- Soft, impact-absorbing, tough core structure
- Excellent resistance to variable and impact loads
- Suitable for precision cold drawing
- Good dimensional stability after heat treatment
- Excellent gear blank material
- Good weldability (before case hardening)
Applications
- Gears and pinions
- Camshafts
- Piston pins
- Worm gears
- Drive shafts
- Bearing races
- Automotive transmission parts
- Agricultural machinery gears and shafts
- Industrial gearbox components
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: 900-950°C (typical duration: 2-12 hours depending on part size)
- 02Case depth (CHD): Typically 0.5-2.0mm
- 03Post-carburizing heat treatment: Water or oil quench + temper at 150-200°C
- 04Surface hardness: 58-63 HRC (after carburizing + quenching)
- 05Core hardness: 30-45 HRC (depends on section size and quench medium)
- 06Delivery condition: +AC (annealed) or +C (cold drawn)
- 07Annealing temperature before cold drawing: 650-700°C
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.
Related Blog Posts
Technical articles, guides and industry analyses
Steel Bar Usage in the Automotive Industry and 2026 Trends
The most commonly used steel bar grades in the automotive industry and 2026 trends. The impact of electric vehicle transition, lightweighting, and sustainability requirements on material selection.
Steel Heat Treatment Processes: Annealing, Quenching & Tempering, Normalizing Guide
A comprehensive guide to steel heat treatment processes. Parameters, suitable steel grades, and proper process selection for annealing, normalizing, quenching & tempering, and case hardening.