Effect of the shot peening process on the fatigue strength of SAE 5160 steel

Abstract

The fatigue behaviour of SAE 5160 steel was evaluated before and after applying a shot peening process by using different Almen intensities and surface coverings (uncovered, partial coverage and total coverage). In the high-cycle fatigue tests, maximum stresses of 0.8 Sut, 0.7 Sut and 0.6 Sut were applied in the three-point bending test on an Instron 8872 servo-hydraulic machine at a frequency of 10 Hz and a constant stress ratio of Smin/ Smax = 0.2 for all tests. The fatigue tests were performed based on the ASTM E8, the specimens were classified into six groups for each stress evaluated, and each group consisted of three standardised specimens (ASTM E466). Also, yield strength, ultimate strength, hardness and microhardness were obtained. The Wilcoxon’s non-parametric test was used to statistically compare all the mechanical properties obtained from the base material with those obtained after the application of the shot peening, for the different surface coverings and Almen intensities. The results showed that the shot peening process significantly increases the fatigue strength of the material, with a 94% increase in fatigue strength of the fully coated specimens. However, no significant increase in fatigue strength was found due to a change in the Almen intensity value. A high correlation factor was found between the increase in the ultimate resistance and the increase in Almen intensity; however, for the yield stress the correlation was medium and inverse. For hardness and microhardness, the correlation factor was very low. Finally, the microhardness values revealed a 3% increase in Vickers microhardness of the shot peening specimens compared to the untreated specimens.

A novel method for determination of surface treatment effect on mechanical properties of titanium bulk material

“…32 The assumption of rigid striker generally leads to acceptable results with reasonable calculation time. 3 Berkovich indenter model was considered as a perfect conical shape with semi apicalangle of 70.3 degrees as a part of the axisymmetric model which offers the same projected area to depth function as the standard Berkovich indenter. 33 The indenter is usually defined as a perfectly rigid body for the nanoindentation simulation, but to be adapted with the requirement of the impact model, it should be considered as deformed body.…”

Evaluación del perfil de tensiones residuales por granallado en un acero SAE 5160H usando microdureza y difracción de rayos X

“…Ante cargas alternativas, se realizan tratamientos térmicos termoquimicos y termomecánicos, recubrimientos y acabados superficiales que apuntan a mejorar el comportamiento de estos componentes [1], [2]. El granallado es una técnica ampliamente utilizada para mejorar propiedades mecánicas superficiales mejorando la respuesta en fatiga del componente [3], [4]. Este proceso se usa ampliamente en resortes helicoidales y de ballesta usados en la industria automotriz.…”

“…Este proceso se usa ampliamente en resortes helicoidales y de ballesta usados en la industria automotriz. Las tensiones residuales compresivas en componentes bajo cargas cíclicas se inducen para mejorar el comportamiento a fatiga [1], [4]. La cuantificación del efecto del granallado se hace por métodos como la intensidad Almen [5], perforación incremental en huecos ciegos según ASTM -E837 o por difracción de rayos X (DRX) [6].…”

Coupled finite and discrete element shot peening simulation based on Johnson–Cook material model

“…Shot peening (SP) is a mechanical cold working process for enhancing the fatigue strength of materials (alloys and metals) by inducing superficial compressive residual stress (CRS). [1][2][3] The process is a bit complex as it involves striking a surface with thousands of spherical media (shots) at a high velocity sufficient enough to cause plastic deformation. Indents are formed all over the peened region as the shots hit the target, which stretches the surface.…”