球墨铸铁行走轮的低温正火工艺

Low temperature normalizing process of nodular cast iron travel wheel

对一种Cu微合金化球墨铸铁行走轮进行了低温正火工艺试验,获得了850℃和860℃正火后行走轮轮缘和轮辐的显微组织和力学性能数据。分析了合金元素Cu对球墨铸铁组织和性能的影响,以及对奥氏体化及珠光体形成相变温度区间带来的变化。结果表明,试验含Cu的球墨铸铁行走轮850℃正火就可以获得95%珠光体,达到完全正火的状态,力学性能符合QT650-4牌号的要求。比较了850℃和860℃正火后组织和性能,虽然都能满足要求,但860℃正火后表面硬度较850℃正火的高,机械切削性能相对较差。说明试验行走轮正火工艺温度窗口较窄,因此,选择850℃正火工艺为佳。该热处理工艺已在工程上得到应用,生产的行走轮已批量出口。

Low temperature normalizing process test of a kind of Cu microalloyed nodular cast iron travel wheel was carried out,and the microstructure and mechanical property data of the flange and spokes of the travel wheel normalized at 850℃and 860℃were obtained.The effect of alloying element Cu on microstructure and properties of nodular cast iron and the change of the temperature range of austenitization and pearlite transformation were analyzed.The results show that 95%pearlite of the nodular cast iron travel wheel can be obtained by normalizing at 850℃,reaching fully normalized state,and the mechanical properties meet the requirements of QT650-4 grade.Meanwhile,the microstructure and properties after normalizing at 850℃and 860℃are compared.Although the microstructure and properties after normalizing at 850℃and 860℃can meet the requirements,the surface hardness after normalizing at 860℃is higher than that normalized at 850℃,and the mechanical cutting performance is relatively poor.It shows that the temperature window of this travel wheel normalizing process is very narrow.Therefore,it is better to choose the normalizing process at 850℃.The heat treatment process has been applied in engineering,and the produced travel wheels have been exported in batches.