钨对314奥氏体耐热钢抗高温氧化行为的影响

Effect of tungsten on high-temperature oxidation resistance of 314 austenitic heat-resistant steel

采用不连续称重法研究了不同钨质量分数(0、1.5%、2.0%和2.5%)的314奥氏体耐热不锈钢在1000和1100℃空气中的抗高温氧化性能,并采用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)对氧化膜表面形貌、截面形貌以及物相进行分析。结果表明:4种不同钨含量实验钢在1000和1100℃空气中的氧化动力学曲线均遵循抛物线规律。钨元素没有参与氧化膜的构成,实验钢的氧化膜主要由尖晶石氧化物(MnCr_(2)O_(4)、FeCr_(2)O_(4)、Mn_(3)O_(4)以及Fe_(3)O_(4))外层、Cr_(2)O_(3)中间层以及半连续状分布的SiO_(2)内层组成;在同一温度下,随着实验钢中钨含量的增加,其表面氧化膜剥落程度逐渐加重,因而导致抗高温氧化性能也随之变差,这种效果在1100℃下更明显;尽管如此,经测定,4种钢在实验温度下均属于抗氧化性级别。

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 1000 and 1100℃ 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 110℃ 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(MnCr_(2)O_(4),FeCr_(2)O_(4),Mn_(3)O_(4) and Fe_(3)O_(4)),the middle layer of Cr_(2)O_(3) 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 11oo C;nevertheless,it has been determined that all four types of steel belong to the oxidation resistance level at the experimental temperature.