中铬铁素体不锈钢高温氧化行为及热轧粘辊机理

High temperature oxidation behavior and roll stricking mechanism of ferritic stainless steel

采用热重法研究了中铬铁素体不锈钢的高温氧化行为,测定出不同温度条件下的氧化增重曲线,其氧化增重符合抛物线规律,由于溶质铬元素的选择性氧化形成致密的氧化层阻碍离子扩散造成实验钢的氧化激活能较高为560 k J/mol。通过氧化铁皮表面形貌观察,在氧化铁皮表面生成部分异常长大的突起铁-铬尖晶石相,并随着氧化温度升高,有增多和长大趋势。当氧化温度为1100℃时,氧化铁皮出现了分层,氧化铁皮最外层为富铁的氧化物(Fe O和Fe3O4为主),将突起铁-铬尖晶石相包裹住。结合热轧粘辊实验结果表明,突起的铁-铬尖晶石容易划伤轧辊表面形成裂纹源,在后续循环轧制过程中急剧的冷热循环和轧制变形,促进了裂纹形成和扩展,为热轧粘辊提供了形核地点。高温轧制促进表面富铁的氧化物的生成,消除突起铁-铬尖晶石相可有效的降低热轧粘辊。

Behavior of high temperature oxidation of medium chromium ferrite stainless steel was studied by thermal gravimetric analysis（ TGA）. From oxidation curves,the oxidation mass gain per unit area with time was in parabolic relation. The compact oxidation hindered ion diffusion under the selective oxidation of chromium,and the activation energy of medium chromium ferrite stainless steel was560 k J / mol. From the observation of the surface morphology of oxide scale,Fe-Cr spinel was found on the surface of oxide scale,and the Fe-Cr spinel increased as temperature increased. When oxidation temperature reached 1100 ℃,the morphology of the oxide scale was layer structure,FeO and Fe3O4 developed at outermost layer,under which the Fe-Cr spinel developed. The sticking experiment proved that Fe-Cr spinel would make the cracks on the surface of roller which formed in the protess of cycling rolling and cooling. Fe-Cr spinel promoted the formation and propagation of cracks,and provided the nucleation sites for sticking. The oxide scale has a protective effect on the surface quality of the slab during hot deformation,decreasing the sticking phenomenon.