To improving the fatigue strength of the root area of a flange and the local rupture strength of a caulking part furthermore besides restraining the deformation of a flange face without changing the unit shape and also without changing a material.
In a bearing unit for a wheel support which is used in the condition where a revolving body for breaking and a wheel are connected and locked by a hub bolt 6a at the side of the flange 6 formed to the outer circumference face of a hub ring 2, the hub ring is made of carbon steel which the carbon content is 0.45 weight % or more and it makes that the hardness is HRC20 to 30 while making at least the flange 6 and the material texture of a caulking part 9 of the hub ring 2 to be pro-eutectoid ferrite of 7 % or less and also the remainder to be spheroidal carbide.
Yoshiaki Naito
Cui Shu Tetsu
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