Q345B钢板坯角部横裂纹成因分析

来源期刊：钢铁钒钛2010年第4期

论文作者：李菊艳 文光华 唐萍 郭秋实

文章页码：56 - 61

关键词：连铸； 微观组织； 横裂纹； 析出物

Key words：continuous casting； microstructures； transverse crack； precipitates

摘    要：用金相显微镜、扫描电镜和能谱仪分析了某钢厂Q345B钢板坯角部横裂纹的特征和成因。结果表明:裂纹是由沿奥氏体晶界析出的MnS复合析出物和先共析铁素体膜造成的。铸坯凝固过程中,微细硫化锰沿奥氏体晶界析出,当铸坯表面温度降低到奥氏体向铁素体转变温度范围时,微细硫化物促进膜状先共析铁素体的形成,受到矫直应力作用时,应力主要集中在膜状铁素体相上,并在硫化物周围形成微孔,微孔聚合导致裂纹的形成。

Abstract: Features and causes of corner transverse cracks for Q345B slab were analyzed based on metallographic microscopy,scanning electron microscopy and energy dispersion scanner.The results shows that the causes of forming cracks are the chain-like manganese sulfide compound and the film-like proeutectoid ferrite precipitated surrounding the austenite grain boundaries.The fine MnS precipitated along the austenite grains boundaries during slab solidification,then further accelerated the formation of thin films proeutectoid ferrite when the temperature of the slab surface droped to the austenite–ferrite transformation temperature range.When the slab was subject to straightening stress,all the strain mainly concentrates in these thin films,encouraging the formation of micropore around the MnS boundaries and these micropore polymerization gradually results in the formation of the crakes.