GB/T700 standard specifies the grades, classification and codes, dimensions, shapes, weights, technical conditions, inspection and testing, packing marks and quality certificates of carbon structural steels.GB/T700 standard applies to the general delivery status, usually used for welding, riveting, bolting engineering structure with hot-rolled steel, steel, steel and steel bar.GB/T700 Standard main steel grade:Q235A,Q235B,Q235C,Q235D,Q275 and so on.