Abstract: The morphology and formation of surface and internal crack of 304 stainless steel 1200 mm×2 mm casting strip produced by twin-roll concasting process were tested and analyzed by scanning electron microscope(SEM). Due to adopting high thermal conduction copper mould, the surface and interal cracks with length up to 140 mm and depth 0.33 mm occurred in strip and there was delamination phenomenon in strip scction. The test results showed that the cooling rate of  molten steel in copper mold came to(1～4)×10³K/s;because strip strand touched low temperature mold roller,the temperature gradient in solidification was up to 10⁵ K/m,the internal stress producad by temperature difference and steess concentration led to crack formation;and the inclusions such as MnS,MnO,Cr₂O₃ are crack initation.

Key words: Concasting Thin Strip,Crack, 304 Stainless Steel

摘要： 用扫描电镜(SEM)观察和分析了双辊连铸法生产的304不锈钢1 200 mm×2 mm铸带表面和内部裂纹的形貌和形成。由于采用导热性好的铜制结晶辊,薄带表面和内部产生了长140 mm、深0.33 mm的裂纹,薄带断面有分层现象。试验结果表明,铜制结晶辊使钢液的冷却速度达到(1~4)×10³K/s,薄带接触辊面温度低,凝固区的温度梯度高达10⁵K/m,温差产生的内应力和应力集中导致裂纹产生;MnS、MnO、Cr₂O₃等夹杂物是裂纹源。

关键词: 连铸薄带, 裂纹 , 304不锈钢