论文部分内容阅读
以复合添加Nb,V和Ti的低碳微合金钢为研究对象,采用热模拟试验机模拟高温轧制+超快速冷却+缓冷工艺,采用OM,HRTEM和显微硬度计等对超快冷至不同温度实验钢的组织转变和析出规律进行研究.结果表明,随着超快冷终冷温度的升高,显微组织由贝氏体向珠光体和铁素体转变,碳化物形核位置从贝氏体转变为铁素体,铁素体中的析出物密度大于贝氏体中的,且在620℃达到最大.超快冷至不同温度时析出物的尺寸均小于10 nm,纵横比均接近于1,即析出物形态更接近于球形,且随终冷温度的降低,析出物尺寸逐渐减小.利用Orowan机制计算了析出强化增量,得出在620℃析出强化对屈服强度的贡献最大,可达到25.6%.
Low carbon microalloyed steel with Nb, V and Ti added as the research object, the hot simulation test machine was used to simulate the high-temperature rolling + ultra-fast cooling + slow cooling technology, and OM, HRTEM and micro- The results show that the microstructure changes from bainite to pearlite and ferrite with the increase of ultra-cold and final cooling temperature, and the carbide nucleation sites From bainite to ferrite, the density of precipitates in ferrite is greater than that in bainite and reaches its maximum at 620 ° C. The size of precipitates in ultra-fast cooling to different temperatures are all less than 10 nm and the aspect ratio Which is close to 1, that is, the shape of precipitates is closer to spherical shape, and the size of precipitates decreases with the decrease of the final cooling temperature.The precipitation increase increment is calculated by Orowan mechanism, and the precipitation strengthening yield strength at 620 ℃ Contribute the most, up to 25.6%.