Optimize the technology data ulteriorly,reduce crack on the interior round billet,enlarge the center equiaxial crystal area and shorten columnar crystal face to amend the quality of round billet.

• 通过进一步优化工艺参数,减少了圆管坯内部裂纹,扩大中心等轴晶区,缩短柱状晶区,使圆管坯质量得以改善,从而提高了圆管坯的穿孔性能,减少钢管内折。