厚规格X70管线钢板探伤不合原因分析及改进措施

Cause Analysis and Improvement Measures of Nonconformity in Ultrasonic Flaw Detection for Thicker Gauge X70 Pipeline Steel Plate

针对济钢生产厚规格X70管线钢板探伤不合的原因,利用金相显微镜、扫描电镜以及能谱仪等检测手段进行显微组织和夹杂物分析。结果表明,中心偏析、组织夹杂物以及同时存在的Nb大型化合物是造成探伤不合的主要原因,采取改善钢水纯净度、延长板坯加热时间和调整连铸、轧制工艺等措施可以提高X70管线钢板的探伤合格率。

For nonconformity of thicker gauge X70 pipeline steel plate in ultrasonic flaw detection, mierostrueture and inclusions of nonconforming steel plate are observed and analyzed by means of metallographic microscope, scanning electron microscope and energy spectrometer. The results show that center segregation, inclusions and co - existed Nb compound are major causes of the nonconformity. The qualification rate of ultrasonic flaw detection for X70 pipeline steel plate can be increased by taking measures of improving steel cleanliness, extending slab reheating time, adjusting casting and rolling process parameters.