Patent ID: 7252721
Filing Date: 2007-08-07
Classification: B21K,C21D,F16C,Y10S,Y10T

Abstract:
1. A power transmission shaft having an electric-resistance welded pipe part made of a steel material and coupling members respectively provided on the opposite ends of the pipe part, wherein the steel material includes 0.30-0.45% by weight of C, 0.05-0.35% by weight of Si, 1.0-2.0% by weight of Mn, 0.05% by weight or less of Al, 0.01% by weight or less of S, and the remainder, iron Fe and unavoidable impurities, and the pipe part has an electro-unite portion that extends in an axial direction, the electro-unite portion and neighborhood thereof being hardened by a hardening treatment so as to have a Rockwell hardness HRC of 45 or more wherein the steel material contains S; and wherein the hardening treatment is a high-frequency induction hardening and tempering treatment.