Effect of tungsten on high-temperature oxidation resistance of 314 austenitic heat-resistant steel
The high-temperature oxidation resistance properties of 314 austenitic heat-resistant stainless steels with different tungsten contents(0,1.5,2.0 and 2.5 wt.％)in atmospheric environment of 1 000 and 1 100 ℃ were investigated by means of discontinuous weighing method.The surface morphology,cross-sectional morphology and phase composition of the oxide scales were analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The results show the oxidation kinetics curves of four different experimental steels at 1000 and 1 100 ℃ all follow the parabolic law.No tungsten element is found in the oxide scale.The oxide scale is mainly composed of the outer layer of spinel oxides(MnCr2O4,FeCr2O4,Mn3O4 and Fe3O4),the middle layer of Cr2O3 and the semicontinuous internal layer of SiO2.At the same temperature,as the tungsten content in the experimental steel increases,the degree of surface oxide film peeling gradually intensifies,resulting in a decrease in high-temperature oxidation resistance.This effect is more pronounced at 1 100 ℃;nevertheless,it has been determined that all four types of steel belong to the oxidation resistance level at the experimental temperature.
tungsten element314 austenitic heat-resistant steelhigh temperature oxidationoxidation kineticsoxide scale
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