超快冷工艺对高强建筑钢组织和力学性能的影响

Effect of Ultra Fast Cooling Process on Microstructure and Mechanical Properties of High Strength Construction Steel

使用真空感应炉冶炼了试验钢,采用不同的控制轧制+超快冷工艺将试验钢轧成12 mm厚的钢板,对钢板金相组织进行了观察,对拉伸和冲击性能进行了检测。结果表明,试验钢组织均为贝氏体+铁素体+少量M-A岛;随着开冷温度升高,铁素体含量减少,抗拉强度和屈服强度明显提高,屈强比略有增加,伸长率降低,冲击功显著提高;随着终冷温度升高,组织中板条贝氏体转变为粒状贝氏体,M-A岛尺寸和含量增加,抗拉强度和屈服强度降低,屈强比显著降低,冲击功先提高后略有降低;随着冷却速率提高,铁素体含量减少,贝氏体板条细化,抗拉强度逐渐升高,屈服强度先升高后降低,屈强比小幅波动,伸长率先下降后保持不变,冲击功略有提高。

The test steel was smelted by using the vacuum induction furnace and rolled into 12 mm thick steel plate by different controlled rolling ＋ ultra fast cooling processes. The microstructure of the steel plate was observed, and the tensile and impact properties were tested. The results show that, the microstructure of test steel is bainite ＋ ferrite ＋ small amount of M-A island; with the increase of cooling temperature, the ferrite content decreases, and the tensile strength and yield strength improve markedly, the ratio of yield and strength also slightly increases, and the elongation reduces while the impact energy significantly increases; with the increase of final cooling temperature, the lath bainite gradually changes into granular bainite, the size and content of M-A island increase gradually, the tensile strength and yield strength decrease, but the ratio of yield and strength decreases significantly, the impact energy firstly increases and then slightly decreases; with the increase of cooling rates, the ferrite content reduces and the bainite lath is refined, the tensile strength gradually increases while the yield strength firstly raises and then reduces, the ratio of yield and strength slightly fluctuates, and the elongation reduces firstly and then keep nearly constant, while the impact energy increases slightly.