Constant velocity universal joint

A constant velocity universal joint comprising:

• an outer joint member;
• an inner joint member arranged inside of the outer joint member;
• and
• torque transmitting members,
• wherein at least one of the outer joint member and the inner joint member comprises track grooves that are engaged with rolling surfaces of the torque transmitting members,
• wherein at least one component of the constant velocity universal joint is formed of a metal sintered compact having pores,
• wherein the metal sintered compact has a relative density of 80% or more and less than 100%,
• wherein the metal sintered compact comprises a heat-treated hardened layer formed on a surface thereof, and
• wherein the surface includes a first surface portion having porous structures densified through partial plastic working, and a second surface portion free from plastic working, the second surface portion retaining a lubricant.