(1) Non-alloy steel. In the past, non-alloy steel was generally referred to as carbon steel. In fact, the connotation of non-alloy steel is broader than that of carbon steel. In addition to ordinary carbon structural steel, high-quality carbon structural steel, carbon cable tool steel, and free-cutting carbon structural steel, non-alloy steel also includes electrical pure iron, raw material pure iron, and other special non-alloy steels with special properties. The mass fractions of carbon are low <0.25%, medium = 0.25%~0.60%, and high >0.60%, respectively.
(2) Low alloy steel. Generally refers to alloy steel with a total alloying element content of less than 5%. In my country's steel classification standard, low alloy steel is listed as a separate category (according to the international classification method, it is included in the alloy steel category). This is mainly due to the large output of low alloy steel in my country and the development of low alloy steel in the world.
(3) Alloy steel. Alloy steel with a total alloying element content greater than 10% is usually called high alloy steel, such as stainless steel and high-speed tool steel. Alloy steel with a total alloy element content of 5% to 10% is called medium alloy steel.
Low alloy steel tube
