Because of high, repetitive stress to the rolling contact areas, fatigue phenomenon will occur to the bearing material after a duration of operation. Loading stress ultimately dislodges a surface section and the bearing fails. To delay the advent of material fatigue, bearing ring and rolling element materials should have the following properties:

● High level of hardness
● High rolling contact fatigue resistance
● Good wear resistance
● Dimensional stability
● Good mechanical strength

Today, carbon chromium steel is one of the oldest and most intensively investigated steels; due to the continuously increasing demands for extended bearing service life. The composition of this rolling bearing steel provides an optimum balance between manufacturing and application performance. This steel is normally given a martensitic or bainitic heat treatment during which it is hardened to the range of 58 to 65 HRC. Vacuum degassed, chromium-bearing steel GCr15 is the standard material for precision bearing rings and rolling elements. The material has uniform specification as SAE52100 (America), DIN100 Cr6 (German), JISSUJ2 (Japan).

Chemical composition of representative carbon chrome bearing steels

Steel No.	Chemical Composition %
GCr 15 SAE52100 JISSUJ2 DIN 100 Gr6	C	Si	Mn	P	S	Cr	Mo	Cu	Ni
	0.95-1.05	0.15-0.35	0.25-0.45	≤0.02	≤0.015	1.4-1.6	0-0.08	0.06-0.02	≤0.2

Because HCH has the competence and facilities to provide a variety of materials, processes and coatings, HCH application engineers can assist in selecting those bearings that will provide superior performance for particular applications.