采用光学显微镜(OM)、场发射扫描电镜(FESEM)观察了C19400合金常规铸造与改进铸造方式制备铸锭及铜带缺陷形貌,通过工业CT V/Tome x m以20 μm的扫描分辨率进行缺陷的3D检测分析.结果表明,通过采用双水冷环的改进铸造工艺方式,铸锭晶粒细化明显,晶粒尺寸约为15 mm,柱状晶区占比较少,而等轴晶区占比较大;铸锭心部等轴晶区试样的工业CT 3D缺陷检测分析和微观组织观察表明,常规铸造方式铸锭中缺陷数量较多,分布呈现网络状,缺陷尺寸达0.599 mm;改进双水冷环铸造中,铸锭中缺陷数量明显较少,分布较为分散,缺陷尺寸约0.161 mm;铜带起泡、起皮和分层缺陷内部颗粒相及条纹和铸态缺陷内部颗粒相和条纹基本一致,该类铜带缺陷由铸锭中的缩松缺陷所致,需要减少铸锭中缩松缺陷.
Effects of Casting Processes on Defects of C19400 Alloy Strip
The defect morphology of ingots and alloy strip fabricated by different casting methods were investigated by optical microscopy(OM)and field emission scanning electron microscopy(FESEM).3D detection of defects were ana-lyzed by CT V/Tome x m with resolution of 20 μm.The results indicate that the grain of ingot by the modified casting process of double water-cooled ring is obviously refined with dimension of 15 mm,and fraction of columnar crystal region is relatively low,while that of equiaxed crystal region is large.CT3D detection and microstructure observation reveal that large quantities of defects are distributed in network by conventional casting method,with dimension of 0.599 mm,while those by improved casting are dipersively distributed with dimension of 0.161 mm.The particle phases and stripe in defects of copper strip foaming,peeling and delamination are basically the same as those in as-cast defects,which are caused by shrinkage defects in the ingot,indicating the necessity to reduce shrinkage defects in the ingot.
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