钒对合金化贝氏体球墨铸铁显微组织和性能的影响

摘要

0.3wt% vanadium (V)was added in the Mo-Ni-Cu-Cr alloyed bainitic ductile iron,then the effects of V addition on the microstructure and mechanical properties of the bainitic ductile iron were investigated.The equilibrium phase diagram of the bainitic ductile iron containing 0.3wt%V was calculated by the thermal-calc thermodynamic software and the precipitation behavior of V was analyzed.The results show that with the addition of 0.3wt% V,the needle-like bainite in the microstructure of the ductile iron became finer;the amount of residual austenite and cementite increased;the nano-scaled VC particles distributed dispersedly in the matrix of bainite. Comparing to the ductile iron without V,the hardness of the ductile iron with 0.3wt%V increased slightly and the impact energy and wear resistance had more than doubled.The main strengthening mechanisms were the fine grain strengthening and precipitation hardening.The wear mechanisms of the ductile irons with and without V were both plastic deformation fatigue and micro-cutting.%在Mo-Ni-Cu-Cr系合金化贝氏体球墨铸铁中添加了质量分数为0．3％的钒，研究了钒的添加对该球墨铸铁显微组织和力学性能的影响；结合 Thermal-Calc热力学软件计算了该含钒球墨铸铁的平衡相图，分析了钒的析出行为.结果表明：当添加0．3％钒后，该球墨铸铁组织中针状贝氏体变得细小，残余奥氏体和渗碳体含量增加，在贝氏体基体中弥散分布着纳米尺度的VC颗粒；添加0．3％钒球墨铸铁的硬度比不加钒的略有增大，冲击功和耐磨性提高了1倍，其主要强化机制为细晶强化和析出强化；含钒和不含钒球墨铸铁的磨损机制均为塑性变形疲劳和显微切削.