Study On Microstructure And Triction And Wear Properties Of Rare Earth Modified Cast Iron

Due to its good castability, fine heat-conducting, excellent machinability, etc., the cast iron material maintains the dominant position in the world casting materials. The rare earth element addition into the cast iron has more than ten-year research history. The research found that the rare earth element addition into cast iron can promote the graphite spheroidization process so as to improve the integrated performance.In order to improve the micro hardness, tensile strength, wear-resisting performance, etc.,this paper adopted cast iron melting method to prepare a new-type cast iron material by adding the dual rare earth elements (La, Ce) and then conducted metallographic observation,SEM analysis, energy spectrum analysis, XRD analysis and mechanics performance testing.The metallographic observation and SEM analysis show that the graphite morphology was changed with the additionof rare earth element, and the spheroidization effect of graphite with 0.6% rare earth addition was obvious in the cashing without cold iron, while the spheroidization effect of graphite with 0.8% rare earth addition was obvious in the cashing with cold iron. With the results of XRD, the amount of cementite was increased with the addition of rare earth in the casting without cold iron. Also, the amount of cementite got increased with the increase of rare earth in the casting with cold iron. The rare earth element showed no obvious changes in the casting structure with or without cold iron, which is basically distributed in the pearlite, ferrite and cementite; however, the rich-rare earth element area was appeared in the casting structure with or without the cold iron after annealing. In compare with experiments of different rare earth content, the strength of extension,microhardness and wear property reached the optimum with 0.6% rare earth addition, of which the strength of extension was 410MPa in the casting without cold iron and 490MPa in the casting with cold iron; themicrohardness in the casting without cold iron was 315.71 HV in the casting with cold iron and 372.89HV in the casting with cold iron; the cooling velocity can be increased to improve its strength of extension and microhardness.Above all, proper rare earth element addition has positive influence on the cast iron's structure and properties. When the rare earth was added by 0.6%, the graphite spheroidization effect was quite obvious with greatly improved mechanical property and abrasive resistance.The proper rare earth element addition can not only meet the performance requirements, but reduce the investment cost, which shall be widely applied in the cylinder liner material.