Carbon Steel Index is based on the mainstream transaction prices in the seven cities. 3. “Long Steel” category comprises rebar (20mm dia, HRB335Mpa) and high-speed wire rod (6.5mm dia), and “Flat Steel” is composed of four steel products, which are steel plate (Q235, 20mm), HRC (SS400, 3.0mm), CRC (SPCC, 1.0mm) and HDG (SPCC, 1.0mm). 4.