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.