Influence of tempering temperature on properties of 30CrMo steel

The properties of 30CrMo steel will change according to the tempering temperature. When the tempering temperature increases, the toughness and plasticity of the 30CrMo steel will increase, but the strength and hardness will decrease.

The hardness of 30CrMo steel hardened at low tempering temperature has no obvious change; tempering at medium temperature, hardness decreased significantly, but at 500℃, there is a linear segment, which is due to secondary hardening. In high tempering stage, The hardness of 30CrMo steel continues to decline. This is because grain growth and solute dissolution occur at high temperatures, which weakens the strengthening mechanisms such as solid solution strengthening and fine grain strengthening, and consequently reduces the strength and increases the plasticity of 30CrMo steel.