轧制条件对消除特厚钢板中心偏析和中心疏松的影响

为了确定特厚板心部质量改善的轧制工艺,制定了传统方法和新型方法生产100mm厚钢板的轧制工艺规程,通过分析低倍、显微组织和夹杂物成分,研究了粗轧、精轧、轧制速度对中心偏析和中心疏松的影响。结果表明：探伤不合的特厚钢板中心存在P和S的偏析,间有氧化铝、硅酸盐和MnS夹杂物；粗轧阶段新型轧制方法对应变积累奥氏体有叠加效应,该叠加效应对消除中心偏析和中心疏松更加有利；精轧阶段的多道次、长时间轧制有利于中心偏析和中心疏松的消除；形状比在0.5~1.0时,采用低速率轧制有利于消除中心偏析和中心疏松；消除中心偏析和中心疏松的临界条件为形状比大于0.518,采用形状比制定轧制规程,比采用道次压下率对消除中心偏析和中心疏松更有效。

Effect of rolling condition on the porosity and segregation annihilation of the heavy steel plate

In order to determine the rolling process for improving the quality of the center of the heavy gauge plate, the traditional and new rolling process rolling pass schedule for producing 100 mm thick plate are formulated. By analyzing the macrostructure, microstructure and inclusion composition, the effects of roughing rolling, finishing rolling and speed on the center segregation and center porosity are studied. The results show that the segregation of P and S exists in the center of the heavy gauge steel plate, and there are inclusions of alumina, silicate and MnS. In the roughing rolling stage, the new rolling pass schedule has a superposition effect on the variable accumulated austenite, which is more advantageous to eliminate the central segregation and the central porosity. In finishing rolling stage, multi pass and longtime rolling are beneficial to the elimination of central segregation and central porosity. When the shape ratio is 0.5 ~ 1.0, low-speed rolling is beneficial to the elimination of central segregation and central porosity. The critical condition for the elimination of center segregation and center porosity is that the shape ratio is greater than 0.518, and it is more effective to use the shape ratio to formulate the rolling pass schedule than the pass reduction rate to eliminate center segregation and center porosity.