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1.Raw material :20Cr/20CrMnTi(structural alloy steel):
?? for spider:20Cr / 20CrMnTi;
?? for bushing:20Cr/GCr15;
?? for needle roller:GCr15.
?? for cross assembly: 20CrMnTi

2.chemical component:
C:0.18~0.24
Si:0.17~0.37
Mn:0.50~0.80
Cr:0.70~1.00
P:≤0.030
S：≤0.030

?3.mechanical property:
Material no：20Cr
Heat treatment：carburizing、quenching、temper
Surface? hardness：58~64HRC
tensile strength(σb)：640
yield strength(σs)：390
flexure-torsion fatigue (σ-1)：305
Shear fatigue(τ-1)：160
Bending stress [σ-1]：60

4.function of u-joint assembly
1).safety factor of static torsion strength:≥2.0
2).torsional fatigue life: ≥1.5x10^5? cycle index.
3).wearing life: ≥60h .

5.heat treatment:
spider:
1).surface hardness:58-64HRC
2).inner hardness:25-45HRC? or 38-48HRC(20CrMnTi)

6.bearing cap:
1).surface hardness:58-64HRC
2).the depth of effective hardened layer:0.3~0.7mm.
3).metallography structure:M+A’1-5 level