The effects of two-phase partial annealing on the impact energy absorption of AR400 steel

This study aimed to evaluate whether the impact resistance of AR400 abrasion-resistant steel, known for its superior tribological properties and wear capabilities, could be enhanced through a two-phased partial annealing heat treatment process while maintaining material hardness and wear resistance.The hypothesis posited that successful heat treatment would improve the wear plate's combined impact and wear resistance, potentially enabling the use of thinner steel materials with comparable wear properties in traditional earth-moving machine wear packages.The study began by establishing the mechanical properties of control specimens through metallurgical analyses for baseline comparison.The Phase 1 heat treatment process involved heating specimens of three different material thicknesses to 1000 C for 20 minutes, followed by oil quenching, which reduced the martensitic content and fostered a predominantly bainitic phase dispersion.Phase 2 involved heating the specimens to 750 C for 20 minutes and rapidly quenching them in cool water.SEM analysis confirmed the bainitic dispersion and revealed that Phase 2 partial annealing only marginally influenced the phase dispersions established in Phase 1.The heat treatment significantly enhanced the materials' impact resistance and toughness but reduced hardness and brittleness.Material elongation nearly doubled across all thicknesses, indicating improved ductility, while Impact testing at -40 C demonstrated substantial increases in impact energy absorption.These findings suggest that while the two-phased partial annealing process holds promise, further refinement is needed to optimise the balance between impact resistance, ductility, tensile strength, and hardness.