The standard bearing material(rings and balls) are chrome steel GCr15, also named AISI SAE52100, DIN 100Cr6, JIS SUJ2, but stainless steel material (440C/316) and ceramic material (Si3N4/ZrO2) are available.

chrome steel GCr15

steel No.Chemical Composition %

stainless steel

specificationtrademarkchemical composition %
GB 30869Cr180.90-1.00below 0.80below 0.80below 0.35below 0.3017.00-19.00
JIS G 4303SUW440C0.95-1.20below 1.00below 1.00below 0.40below 0.3016.00-18.00below 0.75

chrome steel GCr15:

higher hardness and wear resistance
high load
temperature up to 120C
poor corrosion resistance

stainless steel 440C (martensitic stainless steel):

can be hardened, but lower 20% than chrome steel
lower load
temperature up to 250C
good corrosion resistance to weak chemicals, but poor resistance in salt water, acids, alkalis.
with magnetic

stainless steel 316 (austenitic stainless steel):

can’t be hardened
very low load
temperature up to 500C
excellent corrosion resistance to slat water, acids, alkalis

stainless steel 303/304:

used for bearing shields or cage
moderate corrosion resistance

ZrO2 ceramic:

lower load
temperature rang from -190C to +400C without cage
good corrosion resistance, but not for hot water or steam
high fracture toughness for small shock loads

Si3N4 ceramic:

lower load, high speed
temperature range from -210C to 800C without cage
very good corrosion resistance to salt water, acids, alkalis
not shock loads