Effects of Si and Cr on Complete Decarburization Behavior of High Carbon Steels in Atmosphere of 2 vol. % O2

The effects of chemical compositions, especially silicon and chromium contents, on the complete decarburization behaviors of steels in atmosphere of 2 vol. % O2 and 98 vol. % N2 were investigated by using a simultaneous thermal analyzer. Complete decarburization was observed at both 750 and 800 °C for 60Si2MnA steel, while 750 °C only for 92A steel. For GCr15 steel, no decarburization was found at 750 or 800 °C, and only partial decarburization was observed at 850 °C. It indicates that silicon promotes while chromium prevents the complete decarburization of steels in atmosphere with 2 vol. % O2. The main reason is that silicon increases while chromium reduces the equilibrium concentration of ferrite at the interface of ferrite and austenite, which results in the complete decarburization.