HOLLOW MEMBER AND METHOD FOR MANUFACTURING HOLLOW MEMBER.

摘要

A hollow member formed in a tube-like shape and subjected to a torsional force acting about the center axis of the hollow member is characterized in that a part of the peripheral wall of the hollow member is heated to increase the hardness of the outer side of the peripheral wall to a level higher than the hardness of the outer side of the peripheral wall before the part of the peripheral wall is heated and higher than the hardness of the inner side of the peripheral wall, and in that the hollow member is subjected to partial heat treatment which reduces residual stress in the inner side of the peripheral wall.