High strength steel rod and its manufacturing method of rolling PC

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PROBLEM TO BE SOLVED : To provide a high strength rolled PC steel bar having YS (0.2% proof stress) of >=1, 200 MPa, TS of >=1, 400 MPa and elongation of >=4.5%. SOLUTION : This high strength rolled PC steel bar consists of steel containing, by mass, 0.6 to 0.85% C and 1.0 to 3.0% Cr, in which the area ratio of ferrite having lamellar spacing of =80% and has YS (0.2% proof stress) of >=1, 200 MPa, TS of >=1, 400 MPa and elongation of >=4.5%. The steel bar further contains 0.10 to 2.5% Si and 0.25 to 2.0% Mn and suitably contains one or more kinds of Al, Ti, Ca, rare earth metals, V and Nb and/or one or more kinds of B, Cu, Ni and Mo. A wire rod having the chemical composition is isothermally transformed at 450 to 650 deg.C, is imparted with strain of <=4%, and then is subjected to blueing treatment at 200 to 500 deg.C for a holding time of 5 to 600 sec, thereby obtaining the objective steel bar.