HIGH STRENGTH AND HIGH TOUGHNESS STEEL WIRES AND METHOD FOR MAKING THE SAME

摘要

Steel wires which is higher in strength and better in toughness than those wires whose lamellar cementite consists of nano crystals and does not suffer any delamination when subjected to torsion. A steel wire is composed mainly of fine pearlite and/or degenerated pearlite wherein lamellar cementite in the structure is amorphous Alternatively, the wire may be composed mainly of bainite. In this case, the cementite in the structure should be amorphous. For the manufacture of the steel wire, a starting steel product is subjected to patenting and cold drawing repeatedly plural times, followed by final drawing at a true strain of 2.0 or above while cooling.