In this study, porosities in thick slabs were successfully decreased by soft reduction technology coupled with an optimal secondary cooling process. Heat transfer calculation showed that asynchronous solidification occurred in the slab when unreasonable secondary cooling was used. As a result, a W-shaped solidification frontier was formed with two liquid craters near the edges of the solidifying slab. Because of a higher solid fraction in the slab width center, compression of the slab was hindered in the soft reduction and porosities could not be efficiently decreased. Under optimal secondary cooling, viz., with intensified cooling water in the 1/4 width regions while weakened cooling in the 1/2 width region of the slab, a W-shaped solid–liquid frontier was greatly impaired. As a result, effective compression can penetrate into the slab center in soft reduction and porosities are remarkably decreased. Measurements showed volumes of porosities in the 1/4 width and 1/2 width regions of the slab were greatly decreased from 9.063 × 10⁻⁴ to 2.679 × 10⁻⁴ cm³/g and from 2.695 × 10⁻⁴ to 1.728 × 10⁻⁴ cm³/g, respectively.

在这项研究中，厚板坯的孔隙率通过软压下技术和最佳二次冷却工艺成功降低。传热计算表明，当采用不合理的二次冷却时，板坯发生不同步凝固。结果，在凝固板边缘附近形成了带有两个液体坑的 W 形凝固边界。由于板坯宽度中心较高的固含量，板坯的压缩在软压下受阻，不能有效降低孔隙率。在最佳二次冷却下，即., 1/4 宽度区域的冷却水加强，而板坯 1/2 宽度区域的冷却减弱，W 形固-液边界被大大削弱。结果，有效压缩可以在轻压下渗透到板坯中心，并且孔隙率显着降低。测量显示板坯的1/4宽度和1/2宽度区域的孔隙体积从9.063×10 ^-4大大降低到2.679×10 ^-4 cm ³ /g和从2.695×10 ^-4到1.728×10 ^-4厘米³，/克分别。