Nb(C,N)溶解对高铌奥氏体晶粒长大行为的影响

为了定量研究铌对高铌钢加热过程奥氏体晶粒长大的影响，采用化学溶解过滤分离及电感耦合等离子光谱测定不同加热温度两种试验钢固溶铌质量分数，并对比研究了奥氏体晶粒长大行为。结果表明，在低温条件下，低铌钢固溶铌质量分数高于高铌钢；随加热温度升高，高铌钢固溶铌质量分数快速增加，但即使在1 300 ℃时，铌也不能完成固溶，少量铌存在于(Ti,Nb)(N,C)析出相中；奥氏体晶粒快速长大的温度与固溶铌质量分数快速增加的温度有关。随铌质量分数由0.082%增加到0.120%，奥氏体晶粒快速长大的临界温度由1 050升高到1 150 ℃。高铌钢在1 150～1 250 ℃加热温度范围内，奥氏体晶粒尺寸小于100 μm。

Effect of Nb(C,N) dissolution on growth behavior of high Nb austenite grains

In order to investigate the effect of Nb content of high Nb steels on the growth of austenite grain growth during heating process. Means of chemical dissolution, filtration and separation and inductively coupled plasma spectrum were taken to examine the content of dissolved Nb in two high Nb low Ti microallying steels at different temperatures. And a comparative study of the austenite grain growth behavior was carried out. Results showed that the mass fraction of dissolved Nb in low Nb steel was higher than that in the high Nb steel at lower heating temperatures. With heating temperature increasing, the content of dissolved Nb in high Nb steel quickly increased. However, even if heating temperature gets to 1 300 ℃, the Nb can not be completely dissolved. A small amount of Nb existed in (Ti,Nb)(N,C) precipitate. The temperature of the austenite grain quick growth was related to the temperature at which the content of dissolved Nb quickly increased. As the mass fraction of Nb in steels increased from 0.082% to 0.120%, the critical temperature of the austenite grain quick growth arised from 1 050 to 1 150 ℃. For the high Nb steels, the austenite grain size was smaller than 100 μm when heating temperature was in the range from 1 150 to 1 250 ℃.