40Cr steel sheet is one of the most widely used steels in the mechanical manufacturing industry and is suitable for making medium-sized plastic molds.

After quenching and tempering treatment, it has good comprehensive mechanical properties, good low temperature impact toughness and low notch sensitivity. The steel has good hardenability, and can be hardened to 28 to 60 mm when water quenching, and hardened to 15 to 40 mm when oil quenching. This steel is also suitable for cyanidation and high frequency quenching in addition to quenching and tempering. The cutting performance is good. When the hardness is HB174-229, the relative machinability is 60%. The steel is suitable for making medium plastic molds.

According to the production process and application requirements, 40Cr steel plates are classified according to the following conditions:

(1) Classification of chemical components. According to the main types of alloying elements in steel, it can be divided into manganese steel, chrome steel, silicon manganese steel, chromium manganese titanium steel, tungsten chromium vanadium steel and the like. According to the total content of alloying elements in steel, it can be divided into low alloy steel, medium alloy steel and high alloy steel.

(2) Classification use. There are alloy structural steel, alloy tool steel and special performance steel. Such as wear-resistant steel, stainless steel acid-resistant steel, electromagnetic steel, etc.

(3) Classified by metallographic organization. There are ferritic steel, pearlitic steel, martensitic steel and austenitic steel.