Effect of forging ratio on tensile properties and fatigue performance of EA4T steel

In this study, EA4T axle steel was hot-forged using the forging ratios of 2.0, 3.0, 4.0, and 5.0. Effects of the forging ratio on microstructure, tensile properties, and fatigue performance of the steel were investigated. The microstructure was examined by laser scanning confocal microscopy. The fatigue fracture of the forged specimens was observed by scanning electron microscopy. The hardnesses of the billet and the forged samples were measured by a Vickers Indenter. Phase composition and grain size distribution were analyzed. The forged samples using the forging ratio of 4.0 exhibited excellent hardness, mechanical properties, and fatigue behavior. The effects of ferrite volume fraction, acicular ferrite volume, and polygonal ferrite grain size on the mechanical properties were discussed. The relationship between the mechanical properties and the ferrite volume fraction, acicular ferrite volume fraction as well as polygonal ferrite grain size was obtained. According to the analysis of the polygonal ferrite grain size, acicular ferrite, pearlite colonies, and insufficient plastic deformation zone affecting the mechanism of fatigue failure, the effect of the forging ratio on the fatigue life was explored.