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采用热模拟试验和实验室轧钢试验,研究了超低碳贝氏体钢在冷却过程中冷却速率和终冷温度对微观组织和力学性能的影响。结果表明,在相同的冷却速率条件下,随着终冷温度的降低,试验钢的微观组织中板条贝氏体数量逐渐增加,但马奥岛体积分数减少,并且形状由长条状全部转变为球状。相同的终冷温度条件下,试验钢微观组织随着冷却速率的增加,粒状贝氏体组织略为变细,马奥岛尺寸减小、数量减少。轧钢试验中,随着冷却速率的提高和终冷温度的降低,试验钢的屈服强度、抗拉强度和屈强比都增加,但冲击韧性随着冷速的增加而明显改善,400～500℃范围内终冷对韧性影响不明显。
The effects of cooling rate and final cooling temperature on microstructure and mechanical properties of ultra-low carbon bainitic steels during cooling were investigated by means of thermal simulation and laboratory rolling tests. The results show that under the same cooling rate, the number of lath bainite in the microstructure of the test steel increases with the decrease of the final cooling temperature, but the volume fraction of the island of Ma’ao decreases and the shape changes from long strip to full strip For the ball. Under the same final cooling temperature, the microstructure of the test steel with the cooling rate increases, the granular bainite structure is slightly thinned, the size of the island of Maior decreases, the number decreases. In the rolling test, with the increase of cooling rate and the decrease of the final cooling temperature, the yield strength, tensile strength and yield ratio of the test steel increased, but the impact toughness improved obviously with the increase of cooling rate. Within the range of toughness on the cold is not obvious.