Impact fatigue resistance and impact wear resistance of medium Cr-Si cast iron

摘要

A great amount of iron and steel has been consumed on impact abrasive wear such as grinding balls and lining plates in tube mills. Under this working condition the failure of alloy wear resistant white irons is generally caused by fatigue spalling. The wear resistance of martensitic high chromium cast iron (15%Cr) sometimes is not high, but its cost is not low. In the present paper a new wear resistant material―medium Cr-Si cast iron is recommended. It is discussed that the influence of microstructure of the iron is pronounced on impact fatigue resistance and impact wear resistance. Ball-on-ball wear test, high stress impact wear test and field test of the grinding balls have been carried out. The results show that the impact fatigue resistance (IFR) and impact wear resistance (IWR) of medium Cr-Si cast iron are superior to martensitic high chromium cast iron (15%Cr). The main reasons are: (1) the medium Cr-Si cast iron is stress released in the as-cast state; (2) the matrix is fine pearlite; (3) high Si content improves the morphology of eutectic carbide; (4) no secondary carbide resulting in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.