UNIFORM SPEED UNIVERSAL JOINT

摘要

A joint outer ring (4) of a constant-velocity joint (1) has a stem portion (10) protruding from of a cup portion (9) and inserted to a through hole (31) of a hub (27) in a bearing device (2). The joint outer ring (4) has an abutment face (9aa) abutting against an end face of a bearing inner ring (28) fitted to an outer periphery of the hub (27) in an outer bottom face (9a) of the cup portion, and is composed of a forged product of a steel material. The joint outer ring (4) has a base material portion composed of a standard structure and an outer surface layer partially formed as a non-standard structure portion (30). The non-standard structure may be any one of an upper bainite structure, a lower bainite structure and a tempered martensite structure, or a mixed structure of at least two of the structures.