Source：Changjin Metal Product PipeHits：
According to the quality of steel
(1) Ordinary steel The steel contains more impurity elements, the sulfur content ws is generally ≤O.05%, and the phosphorus content is wP≤0.045%, such as carbon structural steel and low alloy structural steel.
(2) High-quality steel has less impurity elements, sulfur and phosphorus content ws, wp, generally ≤0.04%, such as high-quality carbon structural steel, alloy structural steel, carbon tool steel and alloy tool steel, spring steel, bearing Steel, etc.
(3) High-quality steel The steel contains very few impurity elements, the sulfur content ws is generally ≤O.03%, and the phosphorus content is wP≤0.035%, such as alloy structural steel and tool steel. The high-quality steel is behind the steel number and is usually marked with the symbol "A" or the Chinese character "high" for identification.
According to the purpose of steel
First, structural steel
(1) Structural steel for construction and engineering is referred to as steel for construction. It refers to steel used for making metal structural parts in buildings, bridges, ships, boilers or other works. Such as carbon structural steel, low alloy steel, steel and so on.
(2) Structural steel for machine building - refers to steel used to manufacture structural parts on mechanical equipment. These steels are basically high-quality steel or high-quality steel, mainly high-quality carbon structural steel, alloy structural steel, easy-cut structural steel, spring steel, rolling bearing steel.