Tribo-Fatigue Behavior of Austempered Ductile Iron MoNiCa as New Structural Material for Rail-Wheel System

Abstract

Austempered ductile irons exhibit an interesting combination of properties such as low cost, elevated strength, fatigue and wear resistance. This research presents the results of tribo-fatigue behavior of austempered ductile cast iron MoNiCa and gives a comparison with standard grades of steel and cast iron. Due to the possibility to combine the castability of cast iron and toughness of steel in one material, new structural material MoNiCa attracted attention of industry and science because of economic benefits and high performance at the different application areas. After successful former experiments the main directions of further development of research for solving relevant practical wear and fatigue problems in rail-wheel system were framed. The complex experimental studies have demonstrated that MoNiCa is consistent with heat treated steels including the rail steels: required tensile strength of rail steel ranges from 1180 MPa to 1280 MPa when rolling surface hardness have to be from 38 HRC to 44 HRC whereas new structural material showed higher tensile strength up to 1400 MPa and slightly higher hardness up to 50 HRC. Herewith the workability of frictional couple cast iron MoNiCa/steel 20MnCr5G exceeds work performance of steel/steel system by 14 %. Future prospect of this study is to compose mechanical-mathematical model of rail-wheel system, to analyze it under three-dimensional loading, and to execute the field tests of rails under operating conditions.