中文摘要：

应用配有能谱仪的场发射扫描电镜分析了 A105钢中裂纹处及基体内残余元素 Cu、As和 Sn以及 P含量。应用Thermo-Calc热力学计算软件计算了A105钢的主要析出相以及钢液中P含量随固相质量分数变化关系。应用Gleeble 1500热模拟试验机对A105钢的高温热塑性进行了研究。发现P偏析是该钢产生横裂的主要原因，残余元素Cu、As和Sn在晶界的偏聚加剧了裂纹的形成，矫直温度偏低加速了裂纹的扩展，而裂纹的形成可能与AlN的析出无关，因为析出的AlN很少。

英文摘要：

The contents of tramp elements Cu, As and Sn as well as P in A105 continuous casting billets were analyzed by field emission scanning electron microscopy （ FESEM） equipped with energy dispersive spectrometry （ EDS） . Main precipitates in the steel and the variation of P content in molten steel with solid fraction were calculated by Thermo-Calc thermodynamic software. The hot ductility of the steel was measured by using a Gleeble 1500 thermal simulator. It is found that P segregation is the main reason for transverse cracking of the steel. The segregation of tramp elements Cu, As and Sn at grain boundaries promotes the formation of cracks. Straightening in a lower temperature zone accelerates crack propagation. AlN precipitation may have nothing to do with the formation of cracks due to little AlN.