Experimental Investigation of Heat Treatment Parameters on the Wear and Fatigue Behavior of Low-Alloy High-Strength Steels

Abstract

Low-Alloy High-Strength (LAHS) steels are widely employed in aerospace, automotive, railway, offshore, mining, construction, pressure vessel, and defense industries because of their excellent combination of high strength, good toughness, weldability, and cost-effectiveness. However, the wear resistance and fatigue performance of these steels are highly dependent on their microstructure, which is significantly influenced by heat treatment parameters such as austenitizing temperature, soaking time, quenching medium, cooling rate, and tempering temperature. Improper heat treatment may result in excessive brittleness, retained austenite, coarse martensitic structures, residual stresses, and premature fatigue failure under cyclic loading conditions. This research presents an experimental investigation of heat treatment parameters on the wear and fatigue behavior of LowAlloy High-Strength steels through systematic variation of heat treatment conditions followed by comprehensive metallurgical characterization and mechanical testing. The proposed investigation integrates optical microscopy, Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), X-Ray Diffraction (XRD), hardness measurement, tensile testing, pin-on-disc wear testing, rotating bending fatigue testing, and fracture surface analysis. The study evaluates microstructural evolution, martensite formation, bainite transformation, carbide precipitation, retained austenite content, residual stress development, wear mechanisms, crack initiation behavior, fatigue life, and fracture characteristics under different heat treatment schedules. Experimental observations demonstrate that optimized heat treatment significantly improves hardness, wear resistance, fatigue strength, and crack propagation resistance while maintaining adequate toughness and ductility. The findings provide valuable metallurgical guidelines for optimizing industrial heat treatment processes to manufacture durable, reliable, and high-performance Low-Alloy High-Strength steel components suitable for demanding structural and mechanical engineering applications