Classification of structural steels

The content of sulfur, phosphorus and other nonmetallic inclusions in high quality carbon structural steel is lower than that in ordinary carbon structural steel. According to the different carbon content and use, this type of steel is roughly divided into three categories:

1. less than 0.25%C is low carbon steel, especially with carbon content of less than 0.10% of 08F, 08Al, etc., because of its good deep drawing and weldability and is widely used as deep drawing parts such as automobiles, cans...... 20G is the main material for the manufacture of ordinary boilers. In addition, low carbon steel is also widely used as carburizing steel for machinery manufacturing.

2. 0.25 ~ 0.60%C is medium carbon steel, mostly used in the state of tempering, to make parts of the machinery manufacturing industry. Tempering how many 22~34HRC, can get comprehensive mechanical properties, but also easy to cut.

3 more than 0.6%C is high carbon steel, mostly used for the manufacture of springs, gears, rolls, etc., according to the difference in manganese content, it can be divided into ordinary manganese content (0.25 ~ 0.8%) and higher manganese content (0.7 ~ 1.0% and 0.9 ~ 1.2%) two steel groups. Manganese can improve the hardenability of steel, strengthen ferrite, and improve the yield strength, tensile strength and wear resistance of steel. It is usually marked "Mn" after the grade of steel with high manganese content, such as 15Mn, 20Mn to distinguish it from carbon steel with normal manganese content.

The carbon content of carbon tool steel is between 0.65 and 1.35%, and high hardness and high wear resistance can be obtained after heat treatment, which is mainly used in the manufacture of various tools, cutting tools, molds and measuring tools.