特厚钢板探伤不合的原因分析及对策

针对模铸扁锭轧制特厚钢板超声波探伤合格率低的问题,采用低倍、扫描电镜和断口分析等手段对超声波探伤不合钢板的试样进行检验和分析。结果表明,超声波探伤不合的主要原因是模铸扁锭疏松缺陷比较严重。通过增加冒口高度、使用高效发热剂等手段提高扁锭凝固过程中的补缩能力,增加开坯工序,实施两次"高温、低速、大压下"工艺,即可将残留在扁锭中的少量疏松充分压合。

Cause Analysis and Countermeasures of Ultrasonic Detection Disqualification for Extra Heavy Steel Plate

In order to find out the causes of low qualification rate in ultrasonic detection of extra heavy steel plate rolled from slab ingot, testing and analysis have been performed on specimens made from disqualified steel plate in ul trasonic detection by using macro -examination , SEM , fracture analysis and other methods. The results show that ul lrasonic detection disqualification are mainly due to severe porosity defect in slab ingot. The small amount of residual porosity in slab ingot are sufficiently fused in rolling by improving shrinkage filling capacity during solidification of slab ingot with methods of increasing hot top height and applying efficient insulation powder, adding blooming procedure, double implementation of high temperature, low speed, large draft process.