稀土对管线钢中碳化物溶解与析出行为的影响

Effect of Rare Earth on Carbide Dissolution and Precipitation Behavior in Pipeline Steel

以X80管线钢为研究对象,研究了稀土对含铌钢奥氏体化与析出行为的影响。利用热力学固溶度积公式,计算了铌碳化物的溶解温度;借助显微组织观察与硬度测试,对比分析了稀土对高温下奥氏体晶粒粗化及不同温度淬火回火后硬度的影响;通过热模拟实验并利用透射电镜,研究了稀土对实验钢在热变形过程中铌碳氮化物析出行为的作用机制。结果表明:稀土元素的加入降低了碳氮化物的固溶温度,促进了Nb(C,N)等第二相粒子的固溶,稀土能够促进热变形过程中Nb(C,N)的析出,从而提高铌元素的析出强化效果。

Effect of rare earth on the austenitization behavior of Nb-containing steel during the heating process was investigated based on the X80 high grade pipeline steel. Thermodynamic solid solubility calculation were carried out to obtain the solution temperature of niobium carbide,and the effects of the rare earth on austenite grain coarsening and hardness after quenching and tempering under different temperature were contrasted and analyzed through the microstructure observation and hardness test. In addition,the influences of rare earth on niobium carbide precipitation behavior during the subsequent heat treatment process were also studied by means of TEM. The results showed that rare earth elements reduced the temperature of austenite grain size growth in the heating process,and promote the carbonitrides dissolving in the low temperature zone,improve the utilization rate of micro-alloying elements niobium in the process of controlled rolling and controlled cooling.