超快速冷却终止温度对X80管线钢组织和性能的影响

摘要

在试验轧机上对X80管线钢进行了热轧试验，并采用超快冷结合层流冷却的冷却方式对试验钢进行了冷却，结合组织观测，系统研究了超快冷终止温度对力学性能的影响。结果表明：在超快冷终止温度为670℃时，组织中发现了多边形铁素体，试验钢屈强比较低；随着超快冷终止温度的降低，析出物粒子逐渐增多，尺寸逐渐细小且弥散，试验钢的强度和低温韧性逐渐提高，断后伸长率先升高后降低。%Hot rolling test for X80 pipeline steel was carried out at experimental rolling mills. And the test steel was cooled by ultra fast cooling and laminar cooling after rolling. Combined with the microstructure observation, effects of ultra fast cooling ending temperature on mechanical properties were investigated. Results show that when the ultra fast cooling ending temperature was about 670 ℃, polygonal ferrite was found and yield ratio of test steel was lower. With the decreasing of ultra fast cooling ending temperature, the amount of precipitates increased, the size of precipitates was finer and dispersion, the strength and toughness increaseed, elongation first increased and then decreased.