Carbon steel grades and representation

1) ordinary carbon structural steel said the current standard method is: Q x x x - X x. The first letter Q = yield point of Chinese pinyin, XXX for the steel yield strength value ( Unit MPa) The third part of x is the quality level, is divided into A, B two levels, the quality is better than that of A grade B, the fourth part is deoxidized method. A, b, F Z rimming steel, half killed steel, killed steel. (2) high quality carbon structural steel by double digits, said the two Numbers are extremely than average quality carbon steel, high manganese content after the brand in the digital 'Mn', just add 'F' in the boiling. (3) special use of carbon steel, after the brand with the 'R', 'G' (4) carbon steel casting in mid-december, in the first letter and cast steel yield value, and tensile strength values such as ZG200 - Carbon tool steel, 400 (5) with carbon after the first letter 'T' additional Numbers, Numbers are carbon content quality per mil, if it is A high quality carbon tool steel, add A behind the Numbers