Nb微合金钢中析出相演变过程研究

Research on the Evolution Process of Precipitated Phase in Nb-microalloyed Steel

为了探索保温时间对析出过程碳化物团簇组织演变的影响,利用电阻加热法将试样加热至1 200℃,固溶10 min后淬火,然后在700℃保温不同时间,并利用3DAP、XRD和电阻率等手段对其进行研究。试验结果表明,随着保温时间的延长,组织中铁素体含量逐渐增加,而电阻率、点阵常数a,c和c/a轴比均出现了明显的减小;保温30 min左右时,电阻率值最低,且试样中C、Nb原子较淬火态出现了明显的偏聚团簇现象,c/a轴比趋于1,说明此时Nb C碳化物析出比较充分。

In order to explore the influence of heat preservation time on the evolution of clusters during carbide precipitation process, the sample was heated to 1 200℃ by means of resistance heating method, dissolved for 10 min, and then quenched. Finally, its temperature was controlled at about 700 ℃ for different times, and it was investigated by 3DAP, XRD, resistivity method and so on. The experiment results showed that the content of ferrite increased gradually with the extension of heat preservation time, however, the lattice constants, including a, c and c/a ratio, were reduced significantly. The resistivity value became the lowest after 30 min soaking, and there was an obvious cluster segregation for the C, Nb atoms in the sample compared to as-quenched one. At the same time, c/a ratio tended to 1, which illustrated that the NbC was fully precipitated at this time.