Abstract: Precipitates in Nb-Ti microalloying ultra-low carbon bake hardening steel ( % : 0. 002C, 0. 01 ~0. 02Nb, 0. 01 ~0. 02Ti, 0. 002 8 ~0.004 2N) have been studied and expressions for solution C content in test steel were established by quantitative phase analysis. Results showed that increasing calculated value of solution C content, the bake hardening BH₂ value increased； with increasing annealing temperature (810 ~ 850 °C ) of cold rolled plate, the BH₂ value increased ；and as annealed at 820 °C , the BH₂ value of plate coiled at 640 °C was higher than that coiled at 710 °C.

Key words: Nb-Ti Microalloying, ULC Steels, Bake Hardening, Solution C

摘要： 通过定量相分析研究了Nb-Ti微合金化超低碳烘烤硬化钢(%:0.002C、0.01～0.02Nb、0.01～0.02Ti、0.002 8～0.004 2N)的析出相,建立了试验钢固溶C含量的计算公式。结果表明,随固溶C含量计算值的增加,钢板的烘烤硬化性BH₂值增大;随冷轧板退火温度(810～850℃)的增加,BH₂值增加;820℃退火时,640℃卷取的钢板BH₂值高于710℃卷取的钢板BH2值。

关键词: Nb-Ti微合金化, 超低碳钢, 烘烤硬化, 固溶C