高强度工程机械用钢铸坯夹杂物分析

Analysis of inclusions in cast slab for high-strength engineering machinery steel

为了解某厂高强度工程机械用钢Q550MD铸坯夹杂物来源,优化生产工艺,提高铸坯质量,采用大样电解和夹杂物自动扫描分析方法,对铸坯中夹杂物数量、尺寸、形貌及成分进行研究。结果表明,电解试样中大型夹杂物尺寸集中在80~140μm,形状大多为球形,主要成分为铝酸钙。铸坯中大型夹杂物在形成最终复合夹杂物前均来自于钢包,且可能发生结晶器卷渣。检测的铸坯宽度方向1/4位置发现夹杂物聚集现象,夹杂物数量明显高于边部和1/2位置,这与结晶器流场不合理有关。

In order to understand the source of inclusions in Q550MD cast slab of high-strength engineering machinery steel in a plant,optimize the production process and improve slab quality,the number,size,morphology and composition of inclusions in the cast slab were studied by means of slime extraction,automated SEM-EDS inclusion analysis.The results show that the size of macro inclusions in slime extraction sample is concentrated in 80-140μm.The shape of inclusion is mostly spherical,and the main component is calcium aluminate.Before forming the final composite inclusions,the macro inclusions in the cast slab come from the ladle,and the mold flux entrapment may occur.The inclusion aggregation is found at 1/4 position in the width direction of cast slab,and the number of inclusions is significantly higher than that at the edge and 1/2 position,which is related to the unreasonable flow field of the mold.