| 摘要 |
PROBLEM TO BE SOLVED: To provide a wheel bearing device of which the high durability is ensured, by including a part with improved fatigue strength in a non-hardened portion. SOLUTION: A wheel bearing device 1 includes an outer member 10, an inner member 20, and a roller 50. The inner member 20 includes a hub ring 30 made of steel and having a wheel mounting flange 31 formed. The hub ring 30 has a hardened portion 39 hardened to attain at least 50 HRC as a result of quench hardening and a non-hardened portion 33 which is a portion other than the hardened portion 39. A carbide area ratio of steel constituting the non-hardened portion 33 is 10% or less. COPYRIGHT: (C)2008,JPO&INPIT
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