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通过模拟渗碳试验,研究了Nb对齿轮钢20Cr Mn Ti晶粒粗化行为的影响。结果表明,由于析出含Nb析出相,Nb能显著提高在模拟渗碳过程中的晶粒粗化温度。晶粒粗化温度由析出相的体积分数和析出相的尺寸决定。当模拟渗碳温度较低时,时间对析出相尺寸影响不明显;当渗碳温度较高时,延长时间析出相明显粗化。因此,对于Nb含量较低的试样,1 h和6 h模拟渗碳的晶粒粗化温度接近;而对于Nb含量较高的试样6 h模拟渗碳的晶粒粗化温度比1 h的低。
The influence of Nb on the coarsening behavior of 20Cr Mn Ti grains was investigated by simulating carburizing test. The results show that due to the precipitation of Nb-containing precipitates, Nb can significantly increase the grain coarsening temperature during simulated carburization. The grain coarsening temperature is determined by the volume fraction of the precipitated phase and the size of the precipitated phase. When the simulated carburizing temperature is low, the time has no obvious effect on the precipitated phase size. When the carburizing temperature is higher, the precipitated phase is obviously roughened in the extended time. Therefore, for the specimens with lower Nb content, the grain coarsening temperature of simulated carburizing for 1 h and 6 h is close to that for simulating carburizing for 6 h, whereas the coarsening temperature for simulated carburizing for 6 h is higher than that for 1 h Low.