As an important performance index of heat resistant steel, high temperature oxidation resistance has been concerned by many researchers. Special alloy element in steel is to improve and enhance the alloy oxidation resistance, the main reasons for the basic performance guarantee under the premise of properly adding alloying elements is improve and enhance the important reason for the alloy oxidation resistance, alloy elements can fit to join different dense oxide film formed in the steel surface, thus improve the high temperature oxidation resistance.
Heat resistant stainless steel 310S is high chromium and high nickel austenitic stainless steel, which not only has excellent corrosion resistance, mechanical properties, but also has excellent high temperature oxidation resistance, creep resistance. Therefore, it is widely used in a variety of high temperature furnace, high temperature parts in special environment, etc.
The high temperature oxidation mechanism of heat resistant stainless steel 310S has been studied. The researchers of Taiyuan Iron and Steel Group evaluated the high temperature oxidation performance of 310S by studying the high temperature oxidation test in air. Based on the analysis of the oxidation kinetic weight gain curve, the morphology, distribution and structure of the oxide film were studied, and the formation mechanism was explained.
The test sample was taken from TISCO austenitic heat resistant stainless steel 310S hot plate. The chemical composition is shown in the following table (mass fraction, %) : C0.055, Si0.50, Mn1.03, Cr25.52, Ni19.25.
Cut the sample into 30mm× 15mm× 4MMM, 3 parallel samples were used for each test site. The samples were ground, polished with water sandpaper to remove the surface oxide skin and wire-cutting traces, and then cleaned and dried with ethanol. Prepare the same number of crucible as the sample, number it, bake it with a resistance heating furnace, so that the residual material in the crucible fully play, constant mass. The samples oxidized at high temperature were directly placed in the crucible and then put into the box-type resistance furnace for high temperature oxidation. The test atmosphere was air, and the oxidation temperatures were 800, 900 and 1000℃, respectively. The treatment time of each sample was 20, 40, 60, 80, 100, 120 and 140h, respectively. After the oxidation was completed, the weighing instrument was an electronic analytical balance. After the high temperature oxidation test, the phase of the oxidation product was analyzed by X-ray diffractometer, and the surface morphology of the oxide film was analyzed by scanning electron microscope and energy dispersive spectrometer. The analysis results show that:
(1) Heat resistant stainless steel 310S shows good oxidation resistance at 800, 900, 1000℃. With the prolongation of time, there was a trend of oxidation weight gain at different degrees at each temperature, but the trend slowed down with the prolongation of time. At the same time, the oxidation rate increases with the increase of temperature.
(2) The oxide film is composed of dense spinel MnCr2O4 and Cr2O3 in the outer layer and SiO2 in the inner layer. With the increase of temperature, the diffraction peak of MnCr2O4 increases and the products increase. The 3-layer compact structure and the good oxidation resistance of the oxide itself make the heat-resistant stainless steel 310S show good oxidation resistance at high temperature.