The Influence of Copper Content on Rail Steel Properties and Performance
(Room Sagamore 1)
19 Sep 17
11:00 AM
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11:30 AM
Tracks:
AREMA Technical Sessions- Track
Railroad rails manufactured in North America are produced through the efficient and environmentally friendly recycling of steel scrap. This steelmaking methodology can lead to slightly higher copper levels in comparison to other steelmaking practices through the inclusion of small amounts of copper containing materials within the recycled material stream. There have been few systematic studies on the influence of copper on industrially manufactured rail steels. Consequently, a graduate thesis research program was established to provide such data. The effects of increased residual copper levels on rolling contact fatigue (RCF), wear resistance, metallurgical, and mechanical properties were examined by use of disc-on-disc and other laboratory testing. This effort was performed through two successive MS theses at the Colorado School of Mines (CSM) in Golden, Colorado with assistance from EVRAZ Pueblo Product Technology team members. Industrial heats of rail steel with copper levels varying from 0.07% to 0.85% were produced at EVRAZ Pueblo and rolled to premium, high carbon rails that were subsequently machined into various test samples. The RCF and wear behaviors in rolling-sliding contact were evaluated under steady state laboratory conditions; the RCF performance was quantified using eddy current and metallographic examination, while the wear rate was characterized through mass loss and diameter change measurements. RCF and wear surfaces were also characterized by scanning electron microscopy and optical profilometry. Additional characterization included austenitic grain size, Jominy end quench hardenability, microstructure, tensile, hardness, impact toughness, fracture toughness, and fatigue crack growth rate testing.