Nb-H13钢中一次碳化物的析出机理和控制

Precipitation mechanism and improvement of primary carbide in Nb-H13 steel

为了得出铌微合金化H13钢中合适的铌元素添加量,以H13钢中的一次碳化物为研究对象,通过实验室冶炼不同铌元素质量分数的H13钢,系统地研究了Nb-H13钢中一次碳化物的析出机理和合适的Nb添加量。结果表明,当H13钢中铌的质量分数小于0.03%时,Nb-H13钢中的一次碳化物主要为富钒相;当H13钢中铌的质量分数达到0.05%时,Nb-H13钢中的一次碳化物主要为富钒相和富铌相。铌微合金化H13钢中铌元素的添加量应小于0.03%。铌质量分数的高低会显著影响FCC相中碳化物的析出顺序,随着铌质量分数的增加,碳化物的析出顺序由首先析出富钒相转变为首先析出富铌相,且富铌相的热稳定性要远高于富钒相。理论计算结果与试验观察结果基本一致,工业试验结果同样论证了本研究的结论。

In order to obtain the appropriate Nb content in the Nb microalloyed H13 steel, the primary carbide in H13 steel was taken as the research object, and the H13 steels melted in the laboratory with different Nb mass fraction addition were analyzed to study the precipitation mechanism of the primary carbide. The results showed that when the Nb mass fraction in H13 steel is lower than 0.03%, the primary carbide in the H13 steel was mainly the V-rich phase. When the Nb mass fraction in H13 steel reached 0.05%, the primary carbides were mainly the V-rich phase and the Nb-rich phase. Therefore, the Nb mass fraction in the Nb microalloyed H13 steel should be lower than 0.03%. The Nb mass fraction had a significant effect on the precipitation sequence of the primary carbide in the FCC phase. As the Nb mass fraction increased, the precipitation sequence of carbide in FCC phase changes from V-rich phase to Nb-rich phase, and the thermal stability of the Nb-rich phase was much higher than that of the V-rich phase. The theoretical calculation results were basically consistent with the experimental observations, and the industrial test results also demonstrated the results of this study.