改善Q345GJC-Z25钢连铸头坯轧制钢板探伤缺陷实践

Ultrasonic Detected Defect Improvement Practice of Q345GJC-Z25 Steel Plate Rolled from the Head Slab

连铸头坯由于存在疏松、裂纹、偏析、夹杂物等缺陷,用其轧制的钢板经常出现超声波探伤不合格问题。通过对370 mm厚Q345GJC-Z25钢种头坯轧制的80 mm×1938 mm钢板超声波探伤缺陷进行金相和扫描电镜检测分析,确定探伤不合格的原因主要是板厚中心存在微裂纹。围绕微裂纹形成的影响因素对连铸和轧制工艺进行优化、控制,连铸头坯轧制钢板的质量得到明显提升,钢板探伤合格率从原来的73.6%提高到85.2%。

Due to the defects such as porosity,crack,segregation and inclusion in the head slab of continuous casting,the unqualification problems of ultrasonic detection often occur in the steel plate rolled from the head slab.By means of metallography and scanning electron microscopy analysis on the ultrasonic detected defect in 80 mm×1938 mm steel plate rolled from 370 mm thick head slab of Q345GJC-Z25 steel,the microrcracks at the steel plate center are the main cause of ultrasonic flaw detection unqualification.The process of continuous casting and rolling is optimized and controlled aiming at the factors influencing microcrack formation,the quality of the steel plate rolled from head slab is improved significantly,and the ultrasonic detected qualification rate of the steel plate is increased from the previous 73.6%to the current 85.2%.