Water Parameters’ Impact on the Corrosion Behaviour of High-Carbon Pearlitic Rail Steel

Rail steels are high-carbon steels with a predominantly pearlitic microstructure that are commonly utilized in locomotive tyres and big forging dies. The study looks at how salinity, conductivity, total dissolved solids (TDS), and pH affect the corrosion of high-carbon pearlitic rail steel. The research includes pearlitic steels with coarse, fine, and very fine microstructures produced by furnace-cooled, air-cooled, and forced-cooled processes, as well as bainite, martensite, and tempered martensite produced by austempering, water quenching, and tempering of quenched steel, respectively. The research also looks at how water characteristics affect the composition, fractionation, and morphology of corrosion products. In general, salinity and conductivity rise as pH decreases over time. However, the increased TDS and protective index (α/γ*) as measured by the weight fraction of stable α-FeOOH over the other unstable γ-FeOOH and β-FeOOH rust phases eventually induce enhanced corrosion resistance to the steels regardless of their microstructure and interlamellar spacing between ferrite (α-Fe) and cementite (Fe3C). In all situations, air-cooled steel with fine pearlite outperforms furnace-annealed and forced-air-cooled steels. Furthermore, the bainitic microstructure steel is more corrosion resistant than the martensite and tempered martensite microstructure steels.