Hot-rolled rebar is divided into hot-rolled round bars and hot-rolled ribbed bars, cold-rolled bars are hot-rolled bars for cold processing, so that the original strength of the bar to enhance the elongation is reduced (in the range of its elongation in the cold drawn), hot-rolled bars for general cross-section size, span and requirements of the beams and plates are not high, and cold-rolled bars are used for most of the pre-stressing girders and plates and beams and plates with high force requirements.