Bearing Steel Strip

What Bearing Applications Require from Steel Strip

Bearing components can be exposed to concentrated contact stress and demanding dimensional requirements. Grade chemistry alone does not establish suitability: cleanliness, carbide condition, decarburization, heat treatment, geometry and finished-component testing may also govern.

Cold-rolled strip provides a manufacturing path distinct from bar/tube stock: it enables stamped bearing rings, drawn needle cups, and thin-section thrust washers that cannot be economically turned from solid material. The strip route also reduces machining — stamped and formed parts are near-net-shape, requiring only grinding after heat treatment.

Grade Selection for Bearing Applications

Grade	Comparable designations	Hardness reference	Typical candidate uses	Selection note
GCr15	SUJ2 (JIS) / 52100 (AISI) / 100Cr6 (EN)	60-65 HRC	Bearing rings, needle rollers, thrust washers	1.0% C + 1.5% Cr. A commonly referenced grade for rolling-bearing components.
S45C	1045 (AISI) / C45 (EN)	50-58 HRC (induction)	Bearing cages, retainers, low-load races	Medium carbon. Tough core with hard surface after induction hardening. Lower cost for non-critical bearings.
SUS440C	440C (AISI) / X105CrMo17 (EN)	58-62 HRC	Corrosion-resistant bearings, food/marine	17% Cr stainless + 1.0% C. Maintains hardness while providing corrosion resistance. Essential for wet environments.

Microstructure Requirements for Bearing Enquiries

For bearing-grade strip ordered in a spheroidized condition, buyers should define the carbide assessment method, rating limit, sampling frequency and applicable standard. A percentage should not be assumed without an agreed inspection basis.

Carbide distribution: Agree how carbide network, size and distribution will be rated for the intended component and heat treatment.
Formability for stamped rings: Bearing rings and cages stamped from strip require deep drawing without edge cracking. Spheroidized carbides (round, discrete particles in a ferrite matrix) allow plastic flow without carbide network fracture. This means 180° bend test pass and >40% elongation in annealed condition.
Through-hardening response: Define the finished-component hardness, retained-austenite limit, heat-treatment route and dimensional-stability criteria in the engineering specification.
Dimensional precision after heat treatment: Non-uniform microstructure causes non-uniform volume change during martensite transformation. This distortion requires extra grinding stock — increasing manufacturing cost. Uniform spheroidization minimizes heat-treatment distortion to within 0.01mm for stamped ring diameters under 50mm.

Available Specifications

Parameter	Range	Notes
Thickness	Confirm grade-specific availability	State thickness, width, tolerances and measurement method
Width	10mm – 600mm	Custom slit to ring blank width
Surface Finish	Ra ≤ 0.4μm (bright annealed)	Critical for raceway surfaces formed directly from strip
Flatness	≤ 3 I-units	Tight flatness for precision stamping without springback compensation
Delivery Condition	State the required condition	Define metallographic inspection and acceptance criteria where needed
Edge	Slit / Deburred	Deburred edges available for direct-feed to progressive dies

Typical Bearing Components from Strip

Stamped Bearing Rings

Inner and outer races for drawn-cup needle bearings (automotive gearbox, rocker arms). Stamped from GCr15 strip, through-hardened to 60-64 HRC, then precision ground.

Thrust Washers

Flat thrust bearing components stamped from 0.5-2.0mm strip. GCr15 for standard applications, SUS440C for hydraulic systems with fluid exposure.

Needle Bearing Cages

Retainer cages stamped from S45C or GCr15 strip. Require excellent formability in annealed state, then surface hardening for wear resistance against rollers.

Linear Motion Components

Guide rails, slider beds, and flat bearing surfaces for linear guides. GCr15 strip ground to mirror finish after hardening for low-friction sliding contact.

Quality Control for Bearing Steel

Bearing steel may require controls beyond a general cold-rolled strip order. State which of the following tests and documents are required:

Inclusion rating: Non-metallic inclusion content per ASTM E45 or ISO 4967. Oxide type ≤ 1.5, sulfide type ≤ 1.0.
Carbide network rating: Required method, rating limit, sampling location and frequency.
Decarburization check: Total decarburized layer ≤ 1.0% of thickness per side. Verified by microhardness traverse.
Chemical composition: Required ladle or product analysis, certificate type and heat-number traceability.
Surface inspection: Visual + eddy-current testing for surface defects. Maximum permissible defect depth: 0.5% of thickness.

Need bearing-grade strip with specific inclusion limits?
Provide your bearing specification (customer spec or JIS/ISO reference) — we'll confirm compliance and ship test coils for your validation.

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