Growth Law of Solid‐State Decarburization Oxide Layer of Fe–C–Si Alloy Under CO₂–CO Atmosphere

The experiment is carried out on a 0.5 mm Fe‐0.1C‐3.5Si silicon steel. Solid‐state decarburization tests are carried out under CO 2 –CO/H 2 O–H 2 atmosphere to analyze the evolution of the oxide layer in the decarburization process under different atmospheric conditions. The results show that the decarburization effect and decarburization rate in CO 2 –CO atmosphere are significantly better than that in H 2 O–H 2 atmosphere. Under the CO 2 –CO atmosphere, the gas flow rate is 650 mL min −1 , the thickness of the oxide layer increases gradually with the extension of decarburization time. At a gas flow rate of 950 mL min −1 , the thickness of the oxide layer in the cross‐section becomes thicker and thicker with the increase of decarburization time, but the rate of increase of the thickness slows down. As the decarburization temperature increases, the striped SiO 2 oxide band forms between the matrix and the thin oxide layer thickens. The thickness of the oxide layer is about 6.1 μm at the decarburization stagnation, when the banded SiO 2 grooves are more uniform and regular. In H 2 O–H 2 atmosphere, irregular strip‐shaped silicon dioxide grooves form when decarbonization stops, and the thickness of oxide layer is about 15.9 μm.