钢坯高压水除鳞后的表面氧化铁皮形貌及内部组织演变

在不同温度和时间条件下对钢坯进行加热,出炉后利用高压水去除钢坯表面氧化铁皮,然后利用光学显微镜和扫描电镜观察钢坯表面形貌及内部组织,利用XRD分析除鳞后钢坯表面氧化物相组成。结果表明,除鳞后的钢坯表面残留一层氧化铁皮,该层氧化物相组成取决于加热温度和保温时间。低温短时加热时,残留氧化铁皮相组成中含有单质Fe;提高加热温度和延长保温时间使钢基体表面被完全氧化成Fe3O4和Fe2O3。钢坯在炉中长时间高温加热使残留氧化铁皮晶粒粗大,钢坯基体内部出现过热、晶界氧化以及脱碳等问题,加热温度越高、加热时间越长,氧化烧损越严重。

Evolution of surface morphology and internal microstructure of steel billet surface iron oxide after high pressure water descaling treatment

Steel billets were heated under different temperature and time conditions.After being discharged from the furnace the billets were treated using high pressure water to remove surface oxide.Then,the mor-phology of the billet surface iron oxide scale and its internal microstructure were observed by means of optical microscope and scanning electron microscope analyses.After descaling,the composition of the billet surface oxide phase was analyzed by using XRD analysis.The results show that a layer of iron oxide scale remains on the surface of the billet after descaling,and the composition of the oxide phase depends on the heating temper-ature and the holding time.At low temperatures and short holding times,the residual oxide scale consists of el-ementary Fe.Increasing the heating temperature and prolonging the holding time lead to the situation that the surface of the steel matrix is completely oxidized into Fe3O4and Fe2O3.Long time and high temperature heat-ing of the billets in the furnace results in problems such as coarser residual iron oxide grains,overheating of the steel matrix,oxidation of the grain boundary and decarburization,etc.The higher the heating temperature and the longer the heating time,the more serious the oxidation loss is.