40Cr steel is a medium carbon tempered steel, with good hardenability, after tempering treatment, 40Cr steel has good comprehensive mechanical properties , and has a good low notch sensitivity and low-temperature impact toughness, after tempering treatment 40Cr steel is also often high-frequency quenching and nitriding treatment, when the Brinell hardness of 179-229HBS, cutting and machining is better, the relative cutting and machining of 60%, 40Cr easy to manufacture medium-sized molds.
Characteristics: medium carbon modulated steel, cold heading mold steel. The steel is moderately priced, easy to process, after appropriate heat treatment can obtain a certain toughness, plasticity and wear resistance. Normalizing can promote the organization of spheroidization, improve the hardness less than 160HBS blank cutting performance.
Tempered at a temperature of 550 ~ 570 ℃, the steel has the best overall mechanical properties. The hardenability of the steel is higher than 45 steel, suitable for high-frequency quenching, flame quenching and other surface hardening treatments and so on.
Tempering hardness
The hardness of 40Cr after tempering is about 32-36HRC, that is to say about 301-340HB.
40Cr - 830-860 ℃ oil quenching - >55HRC
150 ℃ tempering - 55HRC
200 ℃ tempering - 53HRC
300 ℃ tempering - 51HRC
400 ℃ tempering - 43HRC
500 ℃ tempering - 34HRC
Reference: Baidu Encyclopedia-40Cr