Hollow metal part of stator of rotating electrical machine, rotating electrical machine, and manufacturing process of hollow metal part

There are provided a hollow metal part of a stator of a rotating electrical machine, the rotating electrical machine, a process for manufacturing the hollow metal part. The hollow metal part is excellent in mechanical strength and corrosion resistance and usable as an electrically conductive part without having to change the quality of the material for an interface with another part. The hollow metal part is used as a pipe component for a refrigerant flow path of the rotating electrical machine adapted to cool a stator coil with a refrigerant. The hollow metal part is characterized in that therotating electrical machine includes a connection arm that couples the stator coil and a power supply terminal, and an insulating hose that is coupled to the stator coil and the connection arm through a first hollow metal part in order to supply the refrigerant to the stator coil and the connection arm; and the first hollow metal part is formed integrally by joining a part formed of stainless steel to a part made of oxyg