PRODUCTION OF HIGH-TENSION STEEL BAR MATERIAL

摘要

PURPOSE:To prevent deterioration in breaking strength occuring in warm working by hot rolling a specifically composed steel to a bar shape and subjecting the bar to hardening then tempering thereby producing a high-tension steel bar material to be used with application of warm working. CONSTITUTION:A steel contg. 0.20-0.50% C, 0.5-2.0% Si, 0.9-2.0% Mn, 0.10- 0.60% Cr, <0.005% B and 0.010-0.10% Al or Ti and having 0.85+ or -0.35 value of (Si)/(Mn) is used as a blank material for a steel bar such as PC steel bar which is subjected to a temper heat treatment such as hardening and tempering after hot rolling and is used after warm working. The billet of such steel is hot rolled to a bar shape and is tempered at >=280 deg.C after hardening and thereafter the steel bar is subjected to warm working such as heading. The high-tension steel bar is obtd. without decrease in the breaking strength in the warm worked part.