STEEL BAR OR STEEL WIRE FOR PRESTRESSED CONCRETE HAVING EXCELLENT DELAYED FRACTURE CHARACTERISTIC AND MECHANICAL PROPERTY, MORE PARTICULARLY UNIFORM ELONGATION AND HIGH-TEMPERATURE RELAXATION AND ITS PRODUCTION

摘要

PURPOSE:To provide a titled steel bar or steel wire which can assure uniform elongation satisfactorily as compared with conventional PC steel bars, by treating the bars and wire rods which contain =1 kind among Cr, B and Ti in addition to C, Si, Mn respectively at prescribed ratios and are subjected to prescribed stages so as to allow residual stresses to remain therein. CONSTITUTION:A titled steel bar or steel wire for PC which contains, by weight, 0.10-0.60% C, 0.15-2.0% Si, and 0.6-2.0% Mn and further =1 kind among 0.10-1.0% Cr, 0.0005-0.005% B and 0.01-0.05% Ti. Said steel bar or steel wire are produced in the following way. The components, above all, Si, for heat-treated PC are added positively, and the above-described various elements necessary for obtaining required mechanical properties are incorporated. The three; about =2% slight residual bending stresses, quick heating and the fining of texture resulted from quick cooling are acted synergistically on the steel bars which are heated to prescribed tempering temp. in the tempering stage in a heat-treatment line by quick heating such as high frequency induction heating and quick cooling, whereby the titled steel bar or steel wire for PC is obtained.