| 摘要 |
A joint outer ring of a constant-velocity joint has a stem portion protruding from a cup portion and inserted to a through hole of a hub in a bearing device. The joint outer ring has an abutment face abutting against an end face of a bearing inner ring fitted to an outer periphery of the hub in an outer bottom face of the cup portion, and is composed of a forged product of a steel material. The joint outer ring has a base material portion composed of a standard structure and an outer surface layer partially formed as a non-standard structure portion. The non-standard structure may be a tempered martensite structure, or a mixed structure including the tempered martensite structure and at least one of an upper bainite structure and a lower bainite structure.
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