65Mn宽钢带冷轧边裂原因分析及预防

Cause analysis and prevention of edge cracks in cold-rolled 65Mn wide steel strip

利用金相观察、硬度检测等手段对65Mn宽钢带冷轧过程出现的边裂问题进行了原因分析和研究。结果表明:65Mn钢热轧原料组织为铁素体+珠光体,但由于在热轧水冷过程中边部冷却速度比中间快,珠光体组织片层相对更细。在两相区球化退火过程中,边部较细的珠光体组织更容易被脆性较大的粗珠光体组织所取代。在相对较大的冷轧压下率条件下,造成边部出现裂口。将一次退火工艺由两相区球化退火优化调整为亚温球化退火后,65Mn钢带边部组织球化率显著提高,基本避免了边裂情况的产生,并为实际工业生产提供了积极的指导作用。

Causes of edge cracks in cold-rolled 65 Mn wide steel strip were studied by metallographic observation and hardness test.The results show that the microstructure of the hot-rolled steel strip is ferrite and pearlite,the pearlitic structure in the edge region is relatively thinner than that in the middle region due to faster water-cooling rate.During the intercritical spheroidizing annealing process,these finer pearlites become brittle coarse pearlite more easily,and under the condition of relatively large cold rolling reduction,the edge cracks appear.By substituting the intercritical spheroidizing annealing to subcritical spheroidizing annealing,the microstructure spheroidization rate at the edge of the 65 Mn steel strip is significantly increased,and basically avoiding the occurrence of edge cracks,so that providing positive guidance for the industrial production.