E36-T钢高温力学性能与角部横裂纹控制研究

Research on high temperature mechanical properties and corner transverse crack control of E36-T steel

针对E36-T钢连铸坯角部横裂纹的问题,利用Gleeble-1500热模拟机对E36-T钢进行高温拉伸实验,分析不同温度下的试样在拉伸过程中的真应力-真应变,并利用扫描电镜和金相显微镜对不同温度下拉伸试样的断口形貌及组织进行观察。研究发现:E36-T钢在625~850℃温度范围内发生动态回复,875℃时开始发生动态再结晶;第三脆性区为625~850℃,在第三脆性区的断裂方式以沿晶脆性断裂为主。基于此,通过调整二冷水量,采用弱冷降低冷却强度,使得铸坯在矫直段入口处的温度高于850℃,避开脆性区,降低了裂纹发生率。

Aiming at the problem of the transverse cracks at the corners of the E36-T steel continuous casting slab, the Gleeble-1500 thermal simulator was used to measure the hot ductility of E36-T steel. The true stress-true strain of the samples at different temperature was analyzed. Scanning electron microscope and metallographic microscope was used to observe the fracture morphology and structure of E36-T at different temperature. The results show that the E36-T steel undergoes dynamic recovery within the temperature range of 625 ℃ to 850 ℃, and dynamic recrystallization begins at 875 ℃;the temperature range of the third brittle zone is 625-850 ℃, and the fracture mode of the third brittle zone is mainly intergranular brittle fracture. Based on the above results, optimized the secondary cooling and using weak cooling to reduce the cooling intensity, the temperature of the casting slab at the entrance of the straightening section is higher than 850 ℃, avoiding the brittle zone, and reducing the corner cracks.