52100 Steel vs 440C: Bearing Steel Material Selection Guide

Selecting the correct raw material is the most critical step in bearing manufacturing. Bearings operate under continuous stress, and any defect in the raw steel can lead to premature failure, such as rolling contact fatigue (RCF) or spalling.

When procurement managers and engineers source bearing steel for their turning and grinding operations, they frequently compare two primary grades: 52100 steel and 440C stainless steel.

Additionally, with global supply chains evolving, manufacturers must accurately cross-reference international standards, such as EN31 material (UK) and 1.3505 steel (Europe).

This guide provides a direct, technical comparison of 52100 steel vs. 440c. We will analyze their chemical compositions, material properties, and applications to help you procure the correct raw material for your machining facility.

52100 steel is a high-carbon chromium alloy steel. It is the global standard for bearing manufacturing, accounting for the vast majority of industrial bearings produced worldwide.

Hardness: When properly oil-quenched and tempered, 52100 steel typically achieves a hardness of 60-64 HRC.
Fatigue Life: The primary advantage of 52100 is its high rolling contact fatigue life. It features a uniform microstructure with finely dispersed carbides, which allows it to withstand high radial and axial loads over billions of cycles.
Limitation: 52100 steel has low corrosion resistance. It will rust if exposed to moisture without proper lubrication or sealing.

If your facility manufactures inner rings, outer rings, or rolling elements for automotive, electric motor, or general industrial applications, 52100 round bars or tubes are the standard raw material choice.

440C stainless steel is a high-carbon martensitic stainless alloy. It is primarily specified for environments where standard bearing steel would fail due to oxidation.

Hardness: After heat treatment, 440C can achieve a hardness of 58-60 HRC, making it one of the hardest stainless steel grades available.
Corrosion Resistance: 440C offers excellent resistance to water, steam, and mild chemicals.
Fatigue Trade-off: To achieve high corrosion resistance, 440C contains a high percentage of chromium. This forms large, coarse primary carbides in the steel matrix. These large carbides act as stress concentration points. As a result, the dynamic load capacity and rolling fatigue life of a 440C bearing are typically 20% to 30% lower than a 52100 bearing of the same dimensions.

Procurement teams often receive engineering drawings specifying regional material standards. It is important to know that the following grades are chemically equivalent high-carbon chromium bearing steel:

USA: AISI 52100
UK / Commonwealth: EN31 (BS 970 standard)
Germany / Europe: 1.3505 material (DIN 100Cr6)
China: GCr15
Japan: SUJ2

If your client's drawing requires an EN31 equivalent material, you need to source a high-quality 52100 or GCr15 material. Similarly, 1.3505 steel is the standard European designation for this exact same chemistry.

Sourcing raw materials internationally requires strict quality control. Promisteel supplies Vacuum Degassed (VD) bearing steel round bars that fully comply with AISI 52100, EN31 material, and 1.3505 steel standards. Every shipment includes a complete Mill Test Certificate (MTC).

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The performance differences between these two materials are determined by their chemical composition.

Element	52100 / 1.3505 Steel	440C Stainless Steel	Machining Impact
Carbon (C)	0.95% - 1.10%	0.95% - 1.20%	Both provide high hardness (approx. 60 HRC).
Chromium (Cr)	1.30% - 1.60%	16.00% - 18.00%	440C uses high chromium for corrosion resistance.
Silicon (Si)	0.15% - 0.35%	≤ 1.00%	Acts as a deoxidizer during smelting.
Manganese (Mn)	0.25% - 0.45%	≤ 1.00%	Improves hardenability.

Machinability Considerations: Due to its high chromium content and large carbides, 440C stainless steel is more difficult to machine than standard 52100 steel. It increases wear on carbide turning inserts and requires careful cooling management during grinding to prevent surface burns.

For any bearing application, material cleanliness is critical. Non-metallic inclusions (such as oxygen or sulfur compounds trapped in the steel) can initiate micro-cracks under load.

At Promisteel, our standard bearing steel is vacuum degassed (VD) during the smelting process to minimize these inclusions. For highly critical applications, such as aerospace bearings, we also supply materials processed through Electroslag Remelting (ESR) or Vacuum Arc Remelting (VAR) to ensure maximum metallurgical purity.

Because 440C contains 16-18% chromium, its raw material cost is significantly higher than 52100 steel. Use the following guidelines to specify your material:

General industrial bearings, automotive components, and electric motors.
Applications with adequate oil or grease lubrication.
Projects requiring maximum dynamic load capacity and long fatigue life.
High-volume production where raw material cost control is necessary.

Food processing machinery, medical devices, and marine equipment.
Environments exposed to water, steam, or mild corrosive agents.
Applications where the prevention of rust is prioritized over maximum load capacity.

Choosing between 52100 steel vs. 440C depends on the specific operating environment of the finished bearing. However, the reliability of any bearing begins with the quality of the raw material.

Whether your specifications call for standard AISI 52100, a certified EN31 equivalent material, or European 1.3505 material, Promisteel provides the exact metallurgical grades required by global manufacturers. We supply ultrasonically tested (UT) bearing steel in round bars, wire rods, and forgings.

Contact Promisteel's Sales Team to discuss your raw material requirements and receive a competitive quote.