热连轧403Nb棒材的组织结构与蠕变性能

Microstructures and creep properties of hot continuous rolled 403Nb bar

为了获得403Nb钢更好的加工工艺及优异的高温蠕变性能,借助扫描电镜(SEM)、透射电镜(TEM)、x-射线衍射仪(XRD)等分析手段,并通过蠕变性能测试,对热连轧403Nb钢蠕变前后的组织结构及行为进行了研究.结果表明:403Nb钢在热连轧期间发生了动态回复及动态再结晶,其组成相包括:α-Fe、(Fe,Cr)23C6及(Fe,Cr,Nb)C,其中,(Fe,Cr)23C6多分布于晶界,(Fe,Cr,Nb)C主要分布于晶内.在实验条件下,热连轧403Nb钢具有极强的温度敏感性和应力敏感性,其蠕变激活能Q=287.5kJ/mol.蠕变期间发生了大量的交滑移,碳化物通过阻碍位错运动以及"钉扎"晶界起到提高蠕变抗力的作用.

In order to improve the processing technology and high temperature creep properties of hot continuous rolled 403Nb steel,the microstructures and creep properties before and after creep test were investigated by means of scanning electron microscope （SEM）,transmission electron microscope （TEM）,x-ray diffractometer （XRD） and creep property measurement. The results show that the dynamic recovery and dynamic recrystallization occur during hot continuous rolling,and the microstructure of the steel consists of α-Fe,（Fe,Cr）23C6 and （Fe,Cr,Nb）C phases. The （Fe,Cr）23C6 particles mostly distribute at grain boundaries,and the （Fe,Cr,Nb）C particles mainly distribute within the grains. Under the present experimental conditions,hot continuous rolled 403Nb steel displays the obvious sensibility of temperatures and stresses. And the corresponding activation energy during steady state creep is 287.5kJ/mol. A lot of cross-slip occurs during creep deformation. The existence of carbides can improve the creep resistance by preventing dislocation movement and pinning grain boundaries.