超纯铁素体不锈钢B439M 200 mm x1260 mm连铸板坯中TiN夹杂物的分布

采用自动扫描电镜Aspex研究了超纯铁素体不锈钢B439M(/%:0.01C，0.40Si，0.25Mn，0.020P，0.001S，17.50Cr，0.15Ni，0.20Ti，0.0080N，0.0040O)200 mm×1260 mm连铸板坯中TiN夹杂物的分布,结果表明,由于连铸坯凝固过程中由外向内冷却速率减小,在连铸坯宽度方向边部,生成了大量小尺寸(平均1.26μm?)TiN夹杂物;而在连铸坯宽度方向的1/4处和中部,由内弧表面到厚度1/4处再到厚度方向中部,TiN形核速率降低,TiN夹杂物的数量减少而尺寸增大。动力学分析结果得出,冷却速率减小会使得TiN夹杂物的生成尺寸增大,与TiN夹杂物在连铸坯中的分布规律相吻合。

Distribution of TiN Inclusions in 200 mm x 1260 mm Cast Slab of Ultra-Pure Ferrite Stainless Steel B439M

The distribution of TiN inclusions in 200 mm x 1 260 mm cast slab of ultra-pure ferrite stainless steel B439M (/%： 0.01C, 0.40Si, 0.25Mn, 0.020P, 0.001S, 17.50Cr, 0.15Ni, 0.20Ti, 0.0080N, 0.0040N) has been studied by automated scanning electro microscope Aspex. Results show that due to decrease in cooling rate from surface to inside of cast slab during solidifying process, lots of small size ( average 1. 26 μm) TiN inclusions form at edge of slab width, while at 1/4 of width and center of slab, from narrow side surface to 1/4 of thickness and from 1/4 of thickness to center of thickness the TiN nucleation rate decrease, the amounts of TiN inclusions decrease and size of TiN increases. It is obtained by kinetics analysis that the size of TiN inclusion increases with decreasing cooling rate coincides well with the distribution regulation of TiN inclusions in cast slab.