钒含量对秸秆膨化机螺杆用Cr20高铬铸铁组织与性能的影响

Effect of vanadium content on microstructure and properties of Cr20 high chromium cast iron for straw puffing machine screw

为解决秸秆膨化机螺杆前端磨损严重的问题,对螺杆材质进行研究,通过设计合金成分,向Cr20高铬铸铁中添加不同含量的钒,探究钒含量对高铬铸铁组织与性能的影响,并对添加不同含量钒的Cr20高铬铸铁进行不同温度的淬火与回火处理,借助光学显微镜、扫描电镜、硬度计、冲击试验机及磨损试验机等,探究不同的热处理工艺对不同钒含量Cr20高铬铸铁的微观组织、硬度、冲击性能及耐磨性的影响。结果表明,钒元素的添加使得高铬铸铁在冷却过程中优先从液相中析出碳化钒质点,起到结晶形核作用,从而细化组织,材料的硬度得到提高。钒含量为1.20%时,经990℃×2 h空冷淬火+250℃×2 h空冷回火后高铬铸铁微观组织细小均匀,磨损量较小,相较于钒含量为0%的高铬铸铁耐磨性提升。在钒含量为0.50%时,经990℃×2 h空冷淬火+250℃×2 h空冷回火后冲击性能最好,冲击吸收能量为4.95 J。

To solve the problem of serious wear of the front end of straw puffing machine screw,different contents of vanadium were added into Cr20 high chromium cast iron to study the effect of vanadium content on microstructure and properties,and then the influence of quenching and tempering temperatures on microstructure,hardness,impact property and wear resistance of the tested cast irons was studied by means of optical microscope,scanning electron microscope,hardness tester,impact tester and wear tester.The results show that the addition of vanadium makes the vanadium carbide particles precipitate from the liquid phase preferentially during the cooling process of high chromium cast iron,which plays the role of crystallization nucleation,microstructure refining and hardness improving.After quenching at 990℃for 2 h,air cooling and tempering at 250℃for 2 h,air cooling,the microstructure of the high chromium cast iron with 1.20%V is fine and uniform and the wear loss is less,compared with the high chromium cast iron without V addition,the wear resistance is improved.When the vanadium content is 0.50%under the same heat treatments,the impact property is the best,with an impact absorbed energy of 4.95 J.