What is ordinary carbon structural steel?

What is ordinary carbon structural steel?

Ordinary carbon structural steel is also known as ordinary carbon steel. Carbon content is 0.06-0.22%, and less than 0.25% is most commonly used. It is a mild steel. Each metal grade indicates the lowest yield point of the steel when the thickness is less than 16mm.

Compared with high quality carbon steel, the limits of carbon content, performance range, phosphorus, sulfur and other residual elements are wider. Our country and some countries according to delivery conditions, ordinary carbon steel into three types: A class steel (class A steel), only ensure the mechanical properties, do not guarantee the chemical composition, B class steel (class B steel), only ensure the chemical composition, do not guarantee the mechanical properties; Special steel (Class C steel) ensures both chemical composition and mechanical properties.

Application

This type of steel can be smelted by oxygen converter, open furnace or electric furnace, and is generally hot rolled into plates, steel strips, profiles and bars. Steel plates are usually delivered in hot rolled (including controlled rolling) or normalizing condition. The chemical composition, tensile properties, impact energy and cold bending properties of steel should conform to the relevant regulations.

In China's national standard GB700-88 this kind of steel is divided into 5 grades according to the yield point value, and is divided into 4 grades according to the quality. Its brand is composed of four parts in order: the letter Q representing yield point, yield point value, quality grade symbol and deoxidation method symbol.

These steels have a wide range of applications, most of which are used as welded, riveted or bolted steel structural parts, while a small number are used to make various machine parts. Low strength Q195, Q215 steel used for the production of low carbon steel wire, wire mesh, roof plate, welded steel pipe, anchor bolts and rivets, etc. Q235 steel has moderate strength, good plasticity and toughness, and is easy to form and weld. This steel is used as steel bars and steel structural parts, but also used as rivets, railway spikes and various mechanical parts, such as bolts, tie rods, connecting rods and so on. High strength Q255, Q275 steel used to make a variety of agricultural machinery, also can be used as steel and railway fishtail plate.

According to the special performance requirements of some industrial steel, the composition of ordinary carbon structural steel is slightly adjusted to form a series of professional steel, such as riveting screw steel, bridge steel, pressure vessel steel, hull steel, boiler steel. In addition to strict control of chemical composition and guarantee of conventional performance, professional steel also provides for some special inspection items, such as low temperature impact toughness, aging sensitivity, gas, inclusion and fracture in steel.