Ferrite Decarburization of High Silicon Spring Steel in Three Temperature Ranges

Surface decarburization of high silicon spring steel in ambient air was studied. The experimental results confirmed the decarburized mechanism under AC1 temperature, in the temperature range of AC1-AC3 and AC3-G. Under AC1 temperature, pearlite spheroidization and surface decarburization are carried out simultaneously and pearlite spheroidization is reinforced. Considering the oxidation loss depth, the “true ferrite decarburized depth” at 850 °C (AC3-G) is still smaller than that at 760°C (AC1-AC3). That is because an “incubation period” must pass away before ferrite decarburization occurs in the temperature range of AC3-G, and the ferrite decarburized rate is limited to being equal to the partial decarburized rate.

Surface Decarburization Behavior of Spring Steel 60Si2MnA under AC1 Temperature and in Temperature Range AC3-G

Surface decarburization of spring steel 60Si2MnA heated under AC1 temperature and in temperature range of AC3-G was investigated. The results show that under the AC1 temperature, pearlite spheroidization and surface decarburization were carried out simultaneously and had a mutual promotion relationship. In the temperature range of AC3-G, decarburized layer consisted of complete and partial decarburization, and the complete decarburized depth increased but the partial decarburized depth just a small change with the increase of heating time. Besides, when heating temperature was 790 °C, functional relation between the total decarburized depth, the complete decarburized depth and the heating time follows the formula of and , respectively.