The material of the rolling elements and bearing components require enough hardness and large fatigue strength against repeated force that is due to fatigue fracture of rolling surface which control life of bearings.
To purpose prevent deformation of components due to high load we control limit of elasticity and strength of bearings.
ETC EVO bearings material is GCR15 Steel (JIS G4805) High carbon chromium bearing steel with following chemical composition:

No.	Standard	Symbol	Chemical Composition (%)
			C	Si	Mn	P	S	Cr
1	GB	GCR15	0.98-1.10	0.15-0.35	<0.50	<0.025	<0.025	1.30-1.60
	DIN	100Cr6
	ASTM	E5200
	JIS	SUJ2
2	GB	9Cr18	0.98-1.10	<1.00	<1.00	<0.025	<0.025	16.00-18.00
	DIN	X105CrMO17
	ASTM	440C
	JIS	SUC440C