液-液复合铸造锤头组织和性能的研究

Microstructure and Properties of Liquid-Liquid Composite Cast Hammer

研究了高铬铸铁-碳钢液-液复合铸造锤头的组织、硬度及其复合面元素分布特征。结果表明,液-液复合铸造高铬铸铁锤头在980℃正火+200℃回火后,高铬铸铁部分具有较高硬度,洛氏硬度(HRC)达62,锤柄部分为22,复合面硬度分布平缓,铸铁中C、Cr等合金元素通过复合面向铸钢发生扩散,造成复合面高铬铸铁部分硬度降低,碳钢部分硬度增加。液-液复合面的高铬铸铁侧的组织为马氏体和M7C3型碳化物,碳钢部分为珠光体和较多的铁素体。液-液复合常见的缺陷主要有复合面结合不良、存在气孔及夹杂,合理地控制浇注铸钢后的停留时间、高铬铸铁的浇注温度可防止铸钢复合面缺陷。

Microstructure,hardness and alloy element distribution in composite surface of high chromium cast iron-carbon steel liquid-liquid composite cast hammer were investigated by OM（optical microscope）,SEM（scanning electron microcope）and hardness testing.The experimental results show that high chromium cast iron of liquid-liquid composite cast hammer has a higher hardness of HRC62and carbon steel hammer handle reaches HRC22with normalizing at 900℃and tempering at 200℃,and hardness distribution in composite surface exhibits gradient gradually.Carbon and chromium alloying elements in high chromium cast iron are diffused gradually from composite surface to carbon cast steel,resulting in the increase of hardness of carbon steel part and decrease of high chromium cast iron part.The microstructure of high chromium cast iron is composed of martensite and M7C3type carbide,and carbon steel consists of pearlite and more ferrite near the composite surface.The common defects of high chromium cast iron and carbon steel liquid-liquid composite cast hammer include poor composite surface,porosity and inclusion.Through controlling delayed time and pouring temperature of high chromium cast iron,the casting defects can be eliminated.