中厚板探伤不合的原因分析及控制措施

Cause Analysis and Control Measure of Nonconformity in Ultrasonic Flaw Detection for Medium Heavy Plate

济钢针对钢板探伤综合合格率偏低的问题,对探伤不合的原因进行了分析。统计表明,缺陷部位主要集中在钢板的头部和边部,占统计量的73.74%,主要是长条状和点状密集型缺陷;缺陷类型包括分层、偏析、疏松、白点及夹杂物,并分析了其探伤波形。通过严格控制钢中S和夹杂物含量、改善连铸坯内部质量、保证加热时间、增加单道次压下量、强化热处理的挽救措施,使探伤合格率稳定在99.0%以上。

The reasons of nonconformity in ultrasonic flaw detection for medium heavy plate were analyzed pointing to the lower qualified rate of ultrasonic flaw testing in Jinan Steel. The statistics showed that the defect position mainly concentrate in the head and side of the plate, which proportion is up to 73.74%of statistical quantity and mostly are strip and point-like intensive defects. The defect types included the layering, segregation, porosity, white dot, inclusion and so on. The ultrasonic flaw waves were analyzed. The ultrasonic flaw detection qualified rate obviously improve and was stable to 99% by some countermeasures such as strictly controlling the content of sulfur and inclusion, improving the slab’s internal quality, ensuring the heating time, increasing single-pass reduction, strengthening remedial measures of heat treatment.