2. Channel steel: a long strip steel with a trough-shaped cross section, which belongs to carbon structural steel used in construction and machinery. It is a kind of section steel with complex section, and the section is groove-shaped;

3. Angle steel: steel strip with two sides perpendicular to each other and forming an angle;

4. Rebar: steel must be used for medium-sized and above building components;

5. Steel bar: steel used for reinforced concrete and prestressed reinforced concrete, whose cross section is round and sometimes square with rounded corners.