| 摘要 |
PURPOSE:To manufacture a steel bar having a uniform hardened structure after induction hardening, by subjecting a steel billet contg. specified percentages of C, Si and Mn to heating, hot rolling and water cooling under specified conditions so as to provide specified structures to the resulting steel bar. CONSTITUTION:A steel billet consisting of 0.30-0.60wt.% C, 0.10-0.35wt.% Si, 0.30-2.00wt.% Mn and the balance Fe with inevitable impurities is heated to the Ac3 point +50 deg.C-1,000 deg.C and hot rolled. At this time, the finish rolling is finished at the A3 point - the A3 point +150 deg.C and the surface temp. of the resulting steel bar is immediately reduced to <=600 deg.C by in-line cooling to provide a martensite and/or bainite structure to the surface layer and a fine ferrite-pearlite structure to the interior. Thus, a steel bar suitable for induction hardening and not causing breaking or bending during strain leveling by heat treatment is obtd.
|
