Bearing-grade strip that blanks into a ring or cage, hardens to 60–65 HRC, and survives 10 million rolling-contact cycles — with oxygen content and carbide uniformity controlled at the melt, not after the fact.
Every bearing solves the same problem: a rolling element contacts a raceway under load, millions of times, and the surface must not spall. The material answer is high carbon chromium bearing steel for the loaded parts, and formable low carbon or stainless steel for the cage that holds everything in place. The three families below are how bearing engineers split the assembly by function.
C ~1.0%, Cr ~1.5%. The global standard for bearing rings and rolling elements. Chromium carbides dispersed in a hardened martensitic matrix carry the rolling contact load; after quenching and tempering at 150–180 °C it reaches 60–65 HRC with dimensional stability. The three designations are near-equivalent across GB, EN and JIS standards.
Choose GCr15/100Cr6/SUJ2 for every load-bearing ring and roller.C ≤0.15%, Cr 16–18%, Ni 6–8%. Austenitic stainless that does not quench-harden but work-hardens during forming. Used for bearing cages in corrosive environments (food processing, marine, chemical) and high-temperature applications where low carbon steel would oxidize. Its spring-back resistance holds pocket geometry after stamping.
Choose SUS301 for cages that see moisture, chemicals or elevated temperature.C ≤0.12%, Mn ≤0.50%. Low carbon cold-rolled strip that blanks and deep-draws cleanly in the 0.3–1.0 mm range. It does not harden and does not need to — the cage's job is to separate rolling elements and guide them, not to carry load. SPCC is the lowest-cost, most widely used cage material in volume bearing production.
Choose SPCC for standard stamped cages in dry, normal-temperature environments.Indicative values from production bearing programs; the final spec is agreed at RFQ against your bearing size, load rating and governing standard (GB/T 18254, EN 100Cr6, JIS SUJ2).
| Parameter | Typical value | Why it matters |
|---|---|---|
| Bearing ring strip thickness | 0.5 – 4.0 mm | Miniature and thin-section rings run 0.5–1.5 mm wall; standard deep groove rings run 1.5–4.0 mm |
| Cage strip thickness | 0.3 – 1.0 mm | Stamped cages for miniature bearings run 0.3–0.5 mm; standard industrial cages run 0.6–1.0 mm |
| Delivery condition (bearing steel) | Spheroidized (soft annealed) | Rings blank or turn cleanly; harden predictably to 60–65 HRC with uniform carbide distribution |
| Finished ring hardness | 60 – 65 HRC (after Q&T) | Sets rolling contact fatigue resistance and wear life — the central number in every bearing rating |
| Contact fatigue life | ≥ 10⁷ cycles (L10, rated) | The minimum expected life under standard rolling contact load; driven by cleanliness and hardness |
| Total oxygen content | ≤ 15 ppm (target ≤ 10 ppm) | Oxide inclusions are the dominant fatigue initiation site; lower oxygen directly extends fatigue life |
| Decarburization | ≤ 0.03 mm per side (controlled) | A decarburized surface under-hardens, lowering raceway hardness and initiating premature spalling |
| Carbide uniformity | Fine, uniformly dispersed (controlled) | Large or banded carbides create stress concentrations under rolling contact and reduce fatigue life |
| MTC | Chemistry + oxygen + inclusions + decarb per heat | Traceability for bearing certification, customer PPAP and ISO/TS 16949 audits |
Oxygen content and inclusion rating are measured per heat and reported on the MTC. For high-precision or long-life bearing programs, we can confirm oxygen ≤10 ppm and inclusion severity per ASTM E45 or GB/T 10561. State your cleanliness requirement at RFQ.
Bearing steel supplied spheroidized as standard; cage steels supplied cold-rolled full-hard or annealed per drawing. Choose by component function, environment and governing standard.
| Grade | Standard | Component | Key property |
|---|---|---|---|
| GCr15 | GB/T 18254 | Bearing rings, rollers, sliders | 60–65 HRC, O ≤15 ppm, fatigue ≥10⁷ cycles |
| 100Cr6 | EN ISO 683-17 | Bearing rings, rolling elements | Near-equivalent to GCr15; European standard |
| SUJ2 | JIS G 4805 | Bearing rings, balls, rollers | Near-equivalent to GCr15; Japanese standard |
| SUS301 | JIS G 4313 | Corrosion-resistant cages, thin retainers | Work-hardens, corrosion-resistant, spring-back |
| SPCC | JIS G 3141 | Standard stamped cages, retainers | Excellent blanking & deep-drawing, low cost |
| SPCD | JIS G 3141 | Deep-drawn cages, complex retainers | Better drawability than SPCC for complex cage geometry |
GCr15, 100Cr6 and SUJ2 are near-equivalent grades with minor chemistry differences; confirm the exact standard and revision on your drawing. SPCC/SPCD values are indicative of the JIS G 3141 family — refer to the latest revision for governing limits. All bearing-grade heats include oxygen and inclusion reporting on the MTC.
These are the failure modes that show up in bearing production, in the order bearing engineers care about them.
The dominant bearing failure mode: a subsurface inclusion initiates a crack that propagates to the surface and spalls. Fix: clean steel with total oxygen ≤15 ppm and controlled inclusion severity, measured per heat and reported on the MTC. The melt shop's vacuum degassing and inclusion engineering are the material-side lever.
Miniature rings with 0.5–1.5 mm wall can run soft in the core if hardenability is marginal, or distort if the quench is too aggressive. Fix: GCr15's chromium content provides through-hardening in thin sections; controlled-atmosphere spheroidizing ensures uniform carbide distribution so the quench response is consistent ring to ring.
A decarburized surface layer under-hardens, producing a soft raceway that wears and spalls prematurely. Fix: controlled-atmosphere spheroidizing with measured decarb ≤0.03 mm per side, plus a hardening cycle that does not add decarb. For rings that are not fully ground after hardening, this is a non-negotiable incoming inspection.
Stamped cages with deep pockets or complex geometry can crack at the draw radius if the strip is too hard or has poor ductility. Fix: SPCC or SPCD in the fully annealed or skin-passed condition with confirmed elongation and drawability; we confirm mechanicals per coil and can supply trial coils for draw testing before production.
Bearing assemblies use more than one steel family. Match your component below and confirm at RFQ.
GCr15 / 100Cr6 / SUJ2 high carbon chromium bearing steel for rings, rollers and linear bearing sliders — the core of this page. Bearing steel family →
SUS301 austenitic stainless for corrosion-resistant bearing cages and retainers in food, marine and chemical environments. Stainless steel family →
SPCC / SPCD low carbon cold-rolled strip for standard stamped bearing cages and retainers in volume production. Cold-rolled family →
For linear bearing shafts and certain high-wear rolling elements where tool steel grades are specified instead of bearing steel. Tool steel family →
A typical 608-size bearing (8 mm bore, 22 mm OD, 7 mm width), described the way it runs.
The inner and outer rings are turned or blanked from GCr15 spheroidized strip, 1.2 mm wall thickness for the outer ring and 1.0 mm for the inner. The drawing calls GCr15 per GB/T 18254, oxygen ≤15 ppm, decarb ≤0.03 mm per side, carbide uniformity ≤ grade 3. After blanking, the rings are turned to rough geometry, then through-hardened: austenitizing at 830–850 °C, oil quenching, and tempering at 160–180 °C to 62–64 HRC. The raceways are then ground to a 0.05 μm Ra finish, the rings are super-finished, and the bearing is assembled with seven 3.969 mm Si3N4 or GCr15 balls and a stamped SPCC cage.
The noise test is the moment of truth: every bearing is run at 10,000 rpm and measured for vibration and acoustic noise. A bearing with a subsurface inclusion or a decarburized raceway spot will run noisy and fail the test — and that defect traces directly back to the strip's cleanliness and decarb control. Our job is to make the GCr15's oxygen, inclusion content and decarb so repeatable that the bearing line's variables (grinding, assembly, lubrication) are the only variables left.
The cage is a separate supply line: SPCC 0.4 mm strip, blanked and deep-drawn into a two-piece riveted cage with seven ball pockets. The strip's drawability and surface condition determine whether the cage cracks at the pocket radius during forming. We confirm elongation and earing per coil, and can supply trial coils for draw testing before production commitment.
If your bearing program needs GCr15 rings, SUS301 or SPCC cages, or any combination, send the bearing drawing and we confirm grade, cleanliness level, decarb limit and a trial-coil plan. Our slitting and processing services cover exact-width coils, cut-to-length rings and edge conditioning for blanking or turning. For order and logistics details, see our order process and shipping & logistics pages.
Related reading: how to read a mill test certificate for bearing steel chemistry and cleanliness, and how surface defects and inclusions interact on hardened bearing raceways. For procurement context, see our precision steel strip buyer's handbook.
These grade families share material, processing or application territory with the topic on this page.
GCr15 / 100Cr6 / SUJ2 grades with HRC 60–65 and controlled oxygen for rolling-contact fatigue life.
SUS301 / SUS304 grades with corrosion resistance and work-hardening for bearing retainers and springs.
SPCC / SPCD grades with excellent blanking and deep-drawing for volume bearing cage production.
Send bearing size, wall thickness, cleanliness requirement (oxygen ppm), quantity and destination port. Our engineers reply within one working day with grade match, inclusion reporting and a trial-coil option.