Patent ID: 7942750

Claim:
A constant velocity joint connected to a bearing device to support a wheel, the constant velocity joint comprising: a joint inner ring; a joint outer ring; and a torque transmitting member to transmit a rotation, the torque transmitting member being interposed between the joint inner ring and the joint outer ring, the joint outer ring having a cup portion and a stem portion protruding axially outwardly from an outer bottom surface of the cup portion, the stem portion being inserted to a through hole of a hub of the bearing device, and the cup portion having an abutting face adapted to abut an inboard side end face of a bearing inner ring of the bearing device, which bearing inner ring is mounted on an outer periphery of the hub being provided in the outer bottom surface, the joint outer ring being a hot forged product of a steel material, a matrix material portion thereof representing a standard structure, and a part of the outer surface layer thereof representing a non-standard structure, the non-standard structure being a tempered martensite structure or a mixed structure comprised of the tempered martensite structure and at least one of an upper bainite structure and a lower bainite structure, and the non-standard structure being obtained by cooling at the end of the hot forging step, followed by self-heat-recuperation or heat-recuperation tempering.