Comparison of 40Cr steel and 35CrMo steel

40Cr alloy structural steel, the main function of Cr is to improve the hardenability of the steel, and slightly increase the tempering stability of low-temperature and high-temperature tempering of the steel. At the same time, 40Cr alloy structural steel has temper brittleness, and it should be cooled quickly after high-temperature tempering.

The role of Cr on 35CrMo alloy structural steel is the same as that of 40Cr alloy structural steel. However, 35CrMo alloy structural steel also contains Mo, which further improves the hardenability and tempering stability of the steel, eliminates or reduces the second type of temper brittleness, and has the guarantee of grain refinement.

In general, after quenching and tempering to the same hardness (or the same tensile strength Rm), the tempering temperature of 40Cr steel is lower than that of 35CrMo steel, so its plasticity and toughness are worse than 35CrMo steel. 35CrMo steel has higher hardenability than 40Cr steel, good tempering stability, less tendency of grain growth during quenching heating, and no tendency of temper brittleness.

The comprehensive mechanical properties of 35CrMo alloy structural steel are better than those of 40Cr alloy structural steel. In other words, under the same strength, 35CrMo alloy structural steel has better plasticity and toughness.