Study on the Influence of PE Smoke Atmosphere on the Evolution of Thermal Corrosion Traces of Q235 Steel

In this paper, the characteristics of corrosion traces on the surface of Q235 low carbon steel after being heated at 400 ℃, 600 ℃, and 800 ℃ for 15 minutes and the subsequent evolution of these corrosion traces at room temperature were investigated. Polyethylene (PE) was used as the smoke source, and a comparative study was conducted using macro and micro observation methods, color difference analysis, and other techniques to compare the non-corrosive smoke with the smoke generated from PE combustion. The results show that as the heating temperature increases, the oxide layer on the surface of the steel plate becomes coarser and the proportion of the oxygen (O) element increases. The presence of PE cembrstion gas has a significant influence on the high temperature corrosion of the steel plate. Following high temperature oxidation, the oxide skin on the non-flue gas exposed steel plate appears to be convex and pleated. As the temperature rises, the oxide skin gradually develops cracks and eventually peels off, displaying colors ranging from white to red and then to yellow. The steel plate surface exposed to PE pyrolysis atmosphere exhibits a dimming of its metallic luster and tends to become dark, green, and blue. This leads to the formation of a relatively dense and smooth oxidation layer compared to the non-cembrstion gas exposed steel plate. At 400 ℃, the surface oxidation is non-uniform, displaying a more complex morphology compared to the non-cembrstion gas exposed steel plate. At 600 ℃, the surface experiences significant discoloration; yet the oxidation is relatively smooth and uniform. At 800 ℃, the heated surface becomes rough, with some areas showing convex oxides, but there is no evident blistering or shedding observed on the entire surface. With the increase of corrosion time at room temperature, the change of corrosion traces of the two steel plates at room temperature is relatively small, especially when exposed to PE smoke, the corrosion rate of steel plates at room temperature is partially inhibited.