Bearing Steel

Steel AISI/SAE

High-carbon, high-chromium steel engineered for extreme hardness, wear resistance, and fatigue life in rolling-element bearings.

Bearing steels must withstand millions of rolling contact fatigue cycles under Hertzian contact stresses exceeding 3,000 MPa. Cleanliness is paramount — a single oxide inclusion 15 µm in diameter can initiate a spalling failure. Modern vacuum-degassed bearing steels achieve L10 fatigue lives exceeding 10 billion cycles.

Designation Guide

AISI 52100 (100Cr6 in European notation, SUJ2 in JIS) is by far the most widely used bearing steel, containing 1.0% carbon and 1.5% chromium. For corrosive environments, 440C martensitic stainless or Cronidur 30 (nitrogen-bearing) are specified. Carburizing grades M50NiL and 32CrMoV13 serve high-temperature aerospace bearings.

Selection Tips

52100 is the default for ball and roller bearings operating below 150 °C. Above 150 °C, M50 or M50NiL (case-carburized) maintains hardness. In corrosive environments, consider 440C (lower fatigue life but corrosion resistant) or hybrid ceramic bearings (steel races + Si3N4 balls). Always specify vacuum-degassed or vacuum-remelted steel for critical bearing applications — total oxygen content below 10 ppm dramatically extends fatigue life.

Alloys in this Family

DIN 1.3505 Material 100Cr6 Bearing Steel Equivalent, Composition, Properties, Hardness

Tensile: 1080.0 MPa Yield: 835.0 MPa

GCr15 Steel Equivalent, Chemical Composition, Mechanical Properties

GCr15 vs 52100, 100Cr6 and SUJ2 Bearing Steel Grades

Frequently Asked Questions

What is the Bearing Steel family?
The Bearing Steel family is a group of steel alloys. High-carbon, high-chromium steel engineered for extreme hardness, wear resistance, and fatigue life in rolling-element bearings.
How many alloys are in the Bearing Steel family?
The Bearing Steel family contains 3 published alloys on AlloyFYI.
What metal base does Bearing Steel use?
Bearing Steel alloys are based on steel and follow the AISI/SAE designation system.

Other Steel Families