大规格H型钢腹板冷却浪原因分析及解决措施

腹板冷却浪是大规格H型钢产品一种较难调整的缺陷,其严重影响产品品质和高效生产。以易出现腹板冷却浪缺陷的典型规格H 800 mm×300 mm为例,分析得出缺陷的形成机理是存在残余应力。通过生产试验,针对腹板冷却浪缺陷的主要影响因素,如腹板厚度、腹板与腿部温差、腿腰延伸比,进行了理论分析,并提出了相应改进措施。结果表明,腹板越厚,单位时间内温降后温度越高,因此生产中腹板应按照标准厚度轧制或者正偏差轧制,腿部厚度应尽量轧薄,腰部厚度应尽量轧厚;此外,在TM轧机后安装翼缘冷却装置及在轧机出、入口导卫上部增加挡水板,使轧辊冷却水分流到轧件的两侧,防止落到腹板槽内,加剧其冷却温降,从而减少腹板与翼缘的温差;还有,在轧制过程中保证H型钢腿部延伸较腹板延伸略大,同时保证腹板不受拉,可以平衡一部分轧件热收缩的影响,从而减轻腹板冷却浪的产生。基于上述措施,确保了H800 mm×300 mm等大规格H型钢的质量稳定,为其批量稳定生产提供了保障。

Cause analysis and solution of cooling wave of web of large gauge H-beam

The web cooling wave is a kind of defect which is difficult to adjust in large gauge H-beam products, and it seriously affects product quality and production efficient. Taking the typical size H 800 mm×300 mm which is prone to the defects of web cooling wave as an example, the formation mechanism of the defects was analyzed as the existence of residual stress. Through production tests, the main factors affecting the defects of web cooling wave, such as web thickness, temperature difference between web and leg, leg and waist extension ratio, were analyzed theoretically, and the corresponding improvement measures were put forward. The results show that the thicker of the web, the higher temperature after temperature drop per unit time. Therefore, the web should be rolled according to standard thickness or positive difference in production, the leg thickness should be rolled as thin as possible, the waist thickness should be rolled as thick as possible; In addition, the flange cooling device is installed behind the TM rolling mill and the baffle plate is added on the upper part of the outlet and entrance guide and guard of the rolling mill, so that the roll cooling water is diverted to both sides of the rolled piece to prevent falling into the web groove and increase the cooling temperature drop of web, so as to reduce the temperature difference between the web and the flange. Furthermore, in the process of rolling, the leg extension of H-beam should be slightly larger than that of web, and the web should not be pulled, so as to balance the influence of thermal shrinkage of pieces and reduce the generation of web cooling wave. Based on the above measures, the quality stability of H800 mm×300 mm and other large size H-beam steel were ensured, which provides a guarantee for the stable batch production.