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采用热模拟实验技术、结合维氏硬度测试结果建立了一种低碳Mn-B-Nb-Ti钢的未变形奥氏体CCT曲线和在850℃经50％变形的变形奥氏体CCT曲线．利用光学显微镜、金属薄膜电子显微分析技术研究了冷却速度、变形对显微组织的影响结果表明，微量硼提高了过冷奥氏体的稳定性；随着冷却速度逐渐降低，未变形试样的组织由型贝氏体向型贝氏体变化；变形诱发Nb的用-碳-氮化物析出，提高贝氏体相变温度，促进型贝氏体转变；变形奥氏体的位错缠结抑制贝氏体长大，从而细化转变后的显微组织.
A CCT curve of undeformed austenite and a CCT curve of deformed austenite at 50% deformation at 850 ℃ were established by means of thermal simulation and Vickers hardness test. The effects of cooling rate and deformation on the microstructure were studied by optical microscope and metal thin film electron microscopy. The results showed that the trace boron enhanced the stability of supercooled austenite. With the cooling rate gradually decreasing, the undeformed specimen Of the tissue changes from bainite to bainite; deformation-induced precipitation of Nb with carbon-nitride increases bainite transformation temperature, promoting bainite transformation; dislocation entanglement of deformed austenite Inhibit the growth of bainite, thereby refining the transformed microstructure.