GX40CrNiSi25-12奥氏体耐热铸钢的高温氧化性能

采用恒温氧化试验研究了GX40CrNiSi25-12奥氏体耐热铸钢在不同氧化温度和氧化时间下的抗高温氧化性能,通过氧化质量增加法、光学显微镜、扫描电镜和能谱分析等方法表征分析了试验钢的氧化动力学、氧化膜形貌及成分变化。结果表明,试验钢在850、950和1050 ℃下的氧化动力学曲线均遵循抛物线规律;氧化100 h时,根据GB/T 13303—1991,平均氧化速率均属于1级完全抗氧化性级别。850 ℃和950 ℃下的氧化膜平整致密,由细小均匀密集排布的不规则多边形状氧化物组成;1050 ℃时,氧化膜中氧化物晶粒尺寸不均匀现象加剧。GX40CrNiSi25-12奥氏体耐热铸钢良好的高温抗氧化性与氧化膜中高Cr含量有关。

High temperature oxidation properties of GX40CrNiSi25-12 austenitic heat resistant cast steel

High temperature oxidation resistance of the GX40CrNiSi25-12 austenitic heat resistant cast steel at different oxidation temperatures and time was studied by means of constant temperature oxidation test. The oxidation kinetics, morphologies and composition of oxide films were analyzed by means of oxidation mass gain method, optical microscope, scanning electron microscope and energy dispersive spectrum analysis, respectively. The results show that the oxidation kinetics curves at temperatures of 850 ℃, 950 ℃ and 1050 ℃ all follow parabolic law, and the average oxidation rates oxidized for 100 h at different temperatures are in the range of Grade one standard representing complete anti-oxidation level according to GB/T 13303—1991. At 850 ℃ and 950 ℃, the oxide films are flat and dense, which are composed of small, uniform and densely arranged irregular polygonal oxides. Significant oxide grain size inhomogeneity appears in the oxide film at 1050 ℃. The good high temperature oxidation resistance of the GX40CrNiSi25-12 austenitic heat resistant cast steel is related to the high content of Cr in the oxide film.