400 MPA LEVEL FINE GRAIN THREADED REINFORCING BAR AND MANUFACTURING METHOD THEREFOR

摘要

A 400 MPa level fine grain threaded reinforcing bar and a manufacturing method therefor, relating to the field of threaded reinforcing bar production. The reinforcing bar comprises the following components, by mass percentage, 0.20-0.25% of C, 0.3-0.8% of Si, 1.2-1.6% of Mn, 0.01-0.04% of P, 0.01-0.04% of S, 0.004-0.02% of Ti, 0.001-0.08% of Cr, 0.0001-0.008% of V, 0.0001-0.008% of Nb, 0.0001-0.008% of Al, 0.003-0.01% of O, 0.003-0.01% of N, and with the balance being Fe and unavoidable impurities. The reinforcing bar further comprises manganese silicate inclusion, titanium oxide manganese sulfide complex inclusion, manganese sulfide complex inclusion, and other unavoidable inclusions. The manufacturing method comprises: molten steel smelting, inclusion controlling, continuous casting, continuous casting blank heating, and rolling cooling. According to the method, optimizing designing is performed on the components and the inclusions, smelting and rolling are combined, and a reinforcing mechanism of using the inclusions to induce fine crystalline is adopted, so that the strength of the reinforcing bar is improved, the addition of precious alloy elements is reduced, and the low-cost high-quality production of the threaded reinforcing bars is achieved.