| 摘要 |
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 is composed of steel containing, by weight, 0.8 to 1.3% C and has a pearlitic area ratio of >=80%, in which the quenching multiple D calculated by the formula (1) or (2) is >=1.2, and further, YS is controlled to >=1,200 MPa, TS to >=1,400 MPa and elongation to >=4.5%. The steel bar moreover contains 0.10 to 2.5% Si and 0.25 to 2.0% Mn and contains, as strengthening elements, one or more kinds selected from Al, Ti, Ca, rare earth metals, V and Nb and/or one or more kinds selected from B, Cr, Cu, Ni and Mo: in the case Mn<1.2, D=(C/10)1/2*(1+0.7Si)*(1+3.3 Mn)*(1+2.2Cr)*(1+3(V+Mo))*(1+0.4Ni)*(1+0.4Cu)*(1+0.1B)...(1), and in the case Mn>=1.2, D=(C/10)1/2*(1+0.7Si)*(5.1Mn-1.1)*(1+2.2Cr)*(1+0.4 Ni)*(1+0.4Cu)*(1+0.1B)...(2).
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