Effect of Heat Treatment Process on Impact Properties of 30CrMnSi Steel

The heat treatment process of quenching between Ac1 and Ac3 is called sub-temperature quenching. Sub-temperature quenching can improve the impact performance of steel. For working conditions that require high toughness, this is a relatively good quenching process. The heating temperature is low, the heating time is shortened, and the production efficiency is improved, so it is widely used.

In order to study the hardness and impact properties of 30CrMnSi steel under different quenching processes, two heat treatment processes were selected for research. The first process is a conventional quenching process, the quenching temperature is 910°C, and the tempering temperature is selected according to 230, 330, 430, 530, and 630°C. The second process is quenching at 910°C + tempering at 630°C + sub-temperature quenching at 810°C. After sub-temperature quenching at 810°C, the tempering temperature is selected according to 230, 330, 430, 530, and 630°C. Research indicates:

(1) After conventional quenching at 910°C, the microstructure of 30CrMnSi steel is martensite + retained austenite, and after quenching at 910°C + tempering at 630°C + sub-temperature quenching at 810°C, the microstructure is fine lath Martensite + ferrite + retained austenite.

(2) In the range of 230-630 ° C, with the increase of tempering temperature, the hardness of 30CrMnSi steel under conventional quenching and sub-temperature quenching gradually decreases. When tempering at 630 ° C, both conventional quenching and sub-temperature quenching have hardness Minimum 24 and 22HRC.

(3) In the range of 230-630 ℃, with the increase of tempering temperature, the impact absorption energy curve of 30CrMnSi steel under conventional quenching presents a "W" shape; while the impact absorption energy of sub-temperature quenching increases with the tempering temperature It increases monotonously with the increase of temperature. When it is tempered at 630°C, it has the highest impact absorption energy of 119J, and the best combination of hardness and toughness is obtained.