中厚板超声波探伤不合格成因调查及对策分析

INVESTIGATION ON DISQUALIFICATION OF STEEL PLATE

对连铸板坯轧制中厚板后出现超声波探伤不合格的钢板进行取样 ,通过对试样进行低倍、高倍、刨削、z向剖开、电镜检验以及对钢水进行气体分析 ,找出了引起超声波探伤不合格的主要原因是钢中的氢含量偏高 ,铸坯中心偏析严重和夹杂物较多。其对策是控制原材料水分 ,减少炼钢、精炼、连铸过程增氢 ,延长板坯堆冷时间 ,促进氢的扩散 ,控制铸坯中心偏析程度 。

The samples from steel plates disqualified by ultrasonic inspection were observed macro and micro metallographically, by chopping, dissection in z direction and electron microscopy The gas analysis of the liquid steel was carried out The main causes of disqualification of steel plate are high [H] content in the liquid steel, high central segregation and high inclusion content in slab The countermeasures should be taken to reduce [H], such as decrease of the moisture in raw material, reduction of [H] pick up in steelmaking, refining and continuous casting and prolongation of slow cooling time for slab piles to promote the [H] diffusion The central segregation and inclusion content in cast slab should be controlled too