Carburizing bearing steel is a type of low-carbon alloy structural steel (typically with 0.08–0.23% carbon) containing alloying elements such as chromium, nickel, and molybdenum. After being formed into bearing components, it undergoes a carburizing (or carbonitriding) heat treatment process. This process diffuses carbon into the surface layer, creating a hard, wear-resistant outer case while retaining a tough, ductile inner core.
Key Differences from Ordinary (Through-Hardened) Bearing Steel
Ordinary bearing steel usually refers to high‑carbon chromium bearing steel (e.g., GCr15 / 100Cr6 / SAE 52100), the most widely used grade. The main differences are as follows:
| Aspect | Carburizing Bearing Steel | Ordinary (Through‑Hardened) Bearing Steel | |
| Carbon Content | Low: 0.08–0.23% | High: ~0.95–1.10% | |
| Heat Treatment | Carburizing + quenching + tempering | Direct quenching + low‑temperature tempering | |
| Hardness Profile | Case hard: HRC 58–62Core tough: HRC 25–45 | Uniformly hard throughout: HRC 61–65 | |
| Core Toughness | Excellent (resists impact/shock) | Relatively brittle (lower impact resistance) | |
| Typical Grades | G20CrMo, G20CrNiMo, 8620H, SNCM220 | GCr15, 100Cr6, SUJ2, SAE 52100 | |
| Primary Applications | Heavy‑impact scenarios: railway, rolling mill, heavy machinery, automotive transmission bearings | General‑purpose, high‑speed, heavy‑load bearings (e.g., deep‑groove ball bearings) |
Carburizing bearing steel is designed for high‑impact, shock‑prone applications, offering a hard surface for wear resistance and a tough core for impact absorption.
Ordinary bearing steel provides uniform, ultra‑high hardness across the entire cross‑section, ideal for general‑purpose, high‑precision, high‑speed bearing applications where impact loading is minimal.
