| 摘要 |
PURPOSE:To produce a PC steel bar having excellent strength and toughness by working a specifically composed steel material by hot rolling to a bar material having a prescribed diameter then cooling to cause pearlite transformation and subjecting further the steel material to stretching and bluing treatment. CONSTITUTION:A billet contg. 0.60-0.70% C, 0.50-1.80% Si, 0.30-0.90% Mn and 0.80-1.60% Cr or contg. further <=0.2% 1 or >=2 kinds among Al, Ti and Nb is produced in the stage of producing a PC steel bar. Said billet have such compsn. in which the value of A expressed by the formula I is 80<A<90 and the value of B expressed by the formula II is 1.9<B<2.4. The billet is hot- rolled to a steel bar having >21mm. diam. and is then cooled to cause pearlite transformation. The steel bar is applied with strain by stretching and is subjected to a bluing treatment by a salt bath. The PC steel bar having >110kg/mm.<2> tensile strength, >95kg/mm.<2> yield strength and >5% elongation is produced. |
