摘要
某厂GCr15轴承钢连铸大方坯角部凹陷部位的裂纹导致后续轧材圆棒表面斜向边部裂纹。采用低倍检验、微观组织检验和预制缺口样品断口扫描电镜分析方法,对铸坯角部凹陷部位的裂纹进行分析。结果表明,角部凹陷附近的裂纹沿柱状晶方向延伸,微观显示晶界析出网状碳化物,且晶界上形成严重的疏松孔洞;疏松孔洞内壁为光滑的树枝晶表面特征,直径达到2 mm以上,是由于凝固过程中钢水得不到补充形成的。凹陷部位裂纹是由于连铸坯角部冷却不足,形成严重的疏松孔洞彼此聚合、连接形成的。
The cracks perpendicular to the concaved surface on continuous casting bloom caused the inclined cracks on the surface of rolled bar of high carbon chromium bearing steel GCr15（eqv. AISI 52100）. The origination of the cracks on the bloom has been studied by the methods of macrostructure etch test, microstructure test and fractography SEMEDS analysis of pre-fabricated notch specimens. The results show that the cracks extend along the columnar crystal boundaries, and there are carbide networks and severe micro-cavities on the grain boundary. Exposed dendrites with smooth surface appear in the shrinkage cavities in more than 2 mm diameters. The cracks originate from the formation and coalescence of the severe shrinkage cavities during solidification due to a lack of molten metal, which are caused by seriously weak cooling.
作者
范建文
赵军普
姚同路
于桂玲
FAN Jian-wen, ZHAO Jun-pu, YAO Tong-lu, YU Gui-ling(Central Iron and Steel Institute, Beijing 100081, Chin)
出处
《连铸》
2018年第1期59-64,共6页
Continuous Casting
基金
科技部“十二五”“特殊钢生产流程关键技术开发与集成示范”项目(2012BAE03B00)
关键词
高碳铬轴承钢
连铸坯
角部凹陷
裂纹
high carbon chromium bearing steel
continuous casting bloom
comer depression
cracks
