Q345B低碳高强度钢的高温塑性

使用Gleeble3500热/力模拟机对Q345B低碳高强度钢的高温塑性进行了测定.通过透射电镜、扫描电镜及金相显微镜对析出物形貌、断口形貌和断口组织进行了观察，分析了Q345B钢的断裂机理.结果表明，在1 350~650 ℃范围内，明显存在3个区间，第Ⅰ区温度范围为熔点到1 307 ℃，断裂形式是由S、O等元素偏析引起的沿晶断裂；第Ⅱ区温度范围为1 307~920 ℃，由于动态再结晶的发生，断裂形式为穿晶塑性断裂；第Ⅲ区温度范围为920~650 ℃，断裂形式是由析出物钉扎晶界以及先共析铁素体析出引起的沿晶断裂.分析结论可为连铸生产提供理论依据. 

Hot ductility of low carbon high strength steel Q345B

The hot ductility of low carbon high strength Q345B was determined using thermal analogue machine Gleeble-3500. The precipitates, fracture surface and microstructure of tested samples were observed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical microscopy (OM). The fracture mechanisms were analyzed. The results show that there are three regions between 1 350 ℃ and 650 ℃. The temperature range of regionI is from melting point to 1 307 ℃. The fracture mode is intergranular fracture caused by the segregation of S and O. The temperature range of region Ⅱ is from 1 307 ℃ to 920 ℃. The occurrence of dynamic recrystallization leads to the intragranular fracture. The temperature range of region Ⅲ is from 920 ℃ to 650 ℃. The fracture mode is intergranular fracture caused by the pinning effect of precipitates and the precipitation of pro-eutectoid ferrite along the austenite grain boundaries. The results provide the theoretical basis for the production of continuous casting.