Enhancing mechanical properties and wear resistance of heavy-haul rail systems through complex microstructure control

Abstract

This study delves into the formulation of an advanced microstructure in medium-carbon high-silicon spring steel through a series of engineered heat treatments. The microstructure, composed of lower bainite, proeutectoid ferrite, and pearlite, exhibits superior mechanical properties compared to traditional pearlitic steel. Specifically, the novel microstructure yields a strength of 870 MPa and an ultimate tensile strength of 1050 MPa, along with an enhanced total elongation of 9.75 %, while the pearlitic steel achieved a yield strength of 745 MPa, an ultimate tensile strength of 845 MPa, and a total elongation of 9.0 %. The steel's heightened strength is attributed to dislocation and precipitation strengthening, with the proeutectoid ferrite at grain boundaries contributing to the excellent elongation. The study thus establishes a groundbreaking and readily implementable heat treatment process that significantly boosts the performance and longevity of heavy-haul rail system, owing to the synergistic contribution of lower bainite, proeutectoid ferrite, and pearlite in the microstructure.

Keywords

• AISI 9254 steel
• Surface hardening
• Tribology test
• Internal energy