气体渗氮对F92钢在700℃空气中氧化行为的影响

Effect of gas nitriding on oxidation behavior of F92 steel in air at 700 ℃

利用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射分析(XRD)研究了F92钢供货态和渗氮后在700℃静态空气中的高温氧化行为,阐述了气体渗氮对F92钢氧化行为的影响。研究表明,渗氮后F92钢表面形成了氮的过饱和膨胀铁素体相和CrN相。供货态F92钢表面生成了薄且致密的(Cr,Fe,Mn)_(2)O_(3)和MnCr_(2)O_(4)氧化层,具有良好的保护性。此外,供货态F92钢表面有两种瘤状氧化物生成,一种由连续的Fe_(2)O_(3)构成,另一种独立的由外层Fe_(2)O_(3)和内层富Cr的(Cr,Fe,Mn)_(3)O_(4)组成。渗氮加剧了F92钢的氧化,基体内部观察到了内氧化区。渗氮试样表面氧化膜呈双层结构,其中,外层为Fe_(2)O_(3),内层为富Cr的Fe-Cr氧化物。F92钢渗氮过程中形成的膨胀氮过饱和铁素体相和CrN相以及氧化过程中析出的CrN沉淀相降低了铬的活性,阻碍了有保护性的富铬氧化物的生成,从而导致抗氧化性能的下降。

High temperature oxidation behavior of as-delivered and nitrited F92 steel was studied in static air at 700℃by using scanning electron microscope(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD)and the influence of gas nitriding on oxidation behavior of the F92 steel was elucidated.The results show that an expanded ferrite phase supersaturated with nitrogen and CrN phase are formed on the surface of the nitrided specimen.Thin and dense(Cr,Fe,Mn)_(2)O_(3) and MnCr_(2)O_(4) oxide layers are formed on the surface of the as-delivered F92 steel with good protection.In addition,there are two kinds of nodular oxides on the surface of as-received F92 steel,one is composed of continuous Fe_(2)O_(3),and the other is independent composed of outer Fe_(2)O_(3) and inner Cr-rich(Cr,Fe,Mn)_(3)O_(4).Nitriding aggravates the oxidation of F92 steel,and an internal oxidation zone is observed inside the matrix.The oxide film on the surface of the nitrided specimen has a double-layer structure,in which the outer layer is Fe_(2)O_(3) and the inner layer is Cr-rich Fe-Cr oxide.The expanded nitrogen supersaturated ferrite phase and CrN phase formed during the nitriding process of F92 steel and the CrN precipitation phase precipitated during the oxidation process reduce the activity of chromium and hinder the formation of protective chromium-rich oxides,resulting in a decrease of antioxidant property.