Browsing by Subject "Surface residual stress"

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    Pulsed Nd: YAG laser shock processing effects on mechanical properties of 6061-T6 alloy
    (2014) Gencalp Irizalp S.; Saklakoglu N.; Akman E.; Demir A.
    The aim of this paper is to investigate effects of single and double shot Nd:YAG laser shock processing (LSP) on residual stress, micro-hardness and tensile properties of 6061-T6 aluminum alloy. The X-ray diffraction technique was used to measure surface residual stress in LSP-treated 6061-T6 samples. The magnitude and directional dependence of the surface residual stress after single shot and double shot LSP were investigated with the sin2 Ψ method. The results show that laser shock processing can significantly increase surface compressive residual stress. In addition, micro-hardness of the LSP-treated sample was measured using a Vickers diamond indenter depending on the depth. The tensile tests of the single shot and double shot LSP-treated and untreated samples were carried out by the Schimadzu tensile testing machine having a video extensometer. Experimental results show that the values of micro-hardness, tensile strength and uniform elongation increase by LSP. © 2013 Elsevier Ltd. All rights reserved.
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    Effect of Shot Peening on Residual Stress Distribution and Microstructure Evolution of Artificially Defected 50CrV4 Steel
    (Springer, 2020) Gencalp Irizalp S.; Saklakoglu N.; Baris F.; Kayral S.
    The aim of this paper is to clarify the effects of shot peening on fatigue life and strain hardening behavior of spring steel samples containing artificial surface defect. Artificial defect acting as pre-cracks is introduced and the effects of this defect on the material surface and the distribution of residual stress away from the defect are investigated before and after shot peening. Shot peening has provided the following modifications on the surface: (1) homogenous compressive residual stress, (2) high dislocation density, (3) superficial strain hardening, (4) retained austenite reduction. In this paper, shot peening is applied to 50CrV4 steel and its effect on surface roughness, microhardness, surface residual stress, crystallite size and dislocation density calculation is determined and SEM observations are used to reveal the properties severely strain-hardened layer. It can be shown that the shot peening can modify the crystallite size, however, the main effect is achieved by increasing the dislocation density and inducing the highly compressive residual stress. The effect of the surface modification to the 3-point bending fatigue life are analyzed. © 2020, ASM International.