Q345B厚钢板显微组织中带状组织的形成原因及工艺改进

Formation Reason and Process Improvement of Banded Structure in Microstructure of Q345B Thick Steel Plate

为解决Q345B厚钢板显微组织中带状组织不合格的问题,分析了其带状组织的形成机理和影响因素,并提出了工艺改进措施。结果表明:当钢从奥氏体相区冷却时,铁素体中碳元素聚集,直到温度降低至奥氏体化温度Ar1时,保留到最后的奥氏体转变为珠光体,在轧制过程中珠光体聚集,最终形成铁素体和珠光体带状组织。影响带状组织形成的主要因素为加热温度和终轧温度,可以通过提高终轧温度和在轧制后增加喷水冷却处理来改善Q345B钢板中的带状组织。

In order to solve the problem of unqualiifed banded structure in microstructure of Q345 B thick steel plate, the formation mechanism and influencing factors of banded structure were analyzed, and the process improvement measures were put forward. The results show that when the steel is cooled from the austenite phase zone, the carbon element in ferrite accumulates, until the temperature decreases to the austenitizing temperature Ar1, the retained austenite transforms into pearlite, and the pearlite accumulates in the rolling process, and finally forms ferrite and pearlite banded structure. The main factors affecting the formation of banded structure are heating temperature and finishing temperature. The banded structure of Q345 B steel plate can be improved by increasing finishing temperature and adding water cooling treatment after rolling.