What are the common deep groove ball bearing steels

As one of the most common types of rolling bearings, deep groove ball bearings are widely used in various mechanical fields such as motors, automobiles, home appliances, and industrial transmission equipment. Its performance stability, life and reliability depend largely on the steel material used for the bearing. Different use environments, load conditions and durability requirements put forward diverse technical requirements for the selection of bearing steel.

GCr15 high carbon chromium bearing steel
GCr15 is currently the most widely used bearing steel in China and even in the world. Its corresponding international grades are AISI 52100 (USA), 100Cr6 (Europe), etc. This steel contains about 1.0% carbon and 1.5% chromium, and is a high-carbon high-chromium alloy steel.
Material properties
Extremely high hardness (HRC 60~64)
Excellent fatigue resistance
Good hardenability and stable heat treatment performance
Strong surface wear resistance
Application scenarios
Suitable for most standard industrial applications, including general motors, industrial pumps, gearboxes, compressors, etc.
Limiting factors
Poor corrosion resistance
Sensitive to lubrication conditions
Not suitable for high temperature or highly corrosive environment

Stainless bearing steel (such as AISI 440C)
AISI 440C is a martensitic stainless steel with a high chromium content (about 16%~18%) and a medium carbon content, combining high hardness with good corrosion resistance.
Material properties
Hardness can reach above HRC 58
Excellent corrosion resistance
Can withstand light to medium loads
Good dimensional stability
Application scenarios
Widely used in food machinery, medical equipment, marine equipment, chemical environment, and motors used in humid and high humidity environments.
Limiting factors
Fatigue resistance is slightly lower than GCr15
Higher cost
The heat treatment process is complicated and prone to cracks

Quenched stainless steel (such as AISI 420)
AISI 420 stainless steel is another common bearing stainless steel. Compared with 440C, it has a lower carbon content and better processability and toughness.
Material properties
Good corrosion resistance
Medium strength and wear resistance
More suitable for occasions that require moisture resistance but low load requirements
Application scenarios
Commonly used in low-speed load situations, such as small household appliances, water pumps, simple industrial equipment, etc.
Limiting factors
Hardness and fatigue strength are lower than 440C
Not suitable for high-load and high-speed conditions

High nitrogen stainless steel (such as AISI 14Cr14N)
High nitrogen stainless steel is an emerging high-performance bearing material in recent years. It improves the contradiction between the hardness and corrosion resistance of traditional stainless steel by introducing nitrogen (replacing part of the carbon).
Material properties
High corrosion resistance
Medium to high hardness
Strong pitting resistance
Better resistance to chloride ion corrosion
Application scenarios
Mainly used in special industries that require extremely high corrosion resistance, such as medical equipment, aerospace equipment, and marine engineering.
Limiting factors
High material cost
Difficulty in machining
Complex heat treatment process

Quenched carburized steel (such as 20Cr, 20CrMnTi)
Although not common in most precision bearings, carburized steel still has important application value in some working conditions that require impact resistance.
Material properties
The outer layer can obtain high hardness and the core retains toughness
Good impact resistance
More suitable for bearing structures of large or heavy-loaded low-speed equipment
Application scenarios
Applicable to large-sized deep groove ball bearings or combined bearing components in heavy machinery, metallurgical equipment, and mining equipment.
Limiting factors
High manufacturing cost
Difficult to control the thickness of the carburized layer
High surface precision processing requirements
Ceramic materials (such as silicon nitride Si₃N₄)
Although not a traditional "steel" material, ceramic ball materials are becoming more and more common in deep groove ball bearings, especially in hybrid ceramic bearings (steel rings + ceramic balls).
Material properties
Ultra-high hardness, extremely low density
Excellent high temperature resistance and electrical insulation performance
Extremely low friction coefficient and thermal expansion rate
Application scenarios
Application scenarios with extremely high performance requirements in high-speed spindles, aerospace equipment, high-speed motors, and precision instruments.
Limiting factors
Extremely high cost
Extremely high assembly requirements, prone to edge cracking
Sensitive to impact loads