Fatigue Life Evaluation of Shot Peened Al-Alloys 5083 H11 T-Welded Joints by Experimental and Numerical Approaches

Sidhom, Naziha; Braham, C.; Lieurade, H. P.

doi:10.1007/bf03266548

Cited by 12 publications

(9 citation statements)

References 7 publications

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“…These results are in good agreement with those generated by Ben Fredj in which he reported a 26% increase in the polycyclic fatigue life and an increase of the endurance limit from 226 MPa to 285 MPa of a brushed but ground AISI 304 stainless steel surfaces [6]. The same improvement rate was reported by Sidhom for shot peened and for brushed aluminum alloys [16,17].…”

Section: Contribution Of Surface Strain Work Hardeningsupporting

confidence: 91%

“…As the strain rate is increased, the beneficial effects of the brushing operation are reduced as a result of cyclic stress relaxation as shown in Table 9. These results are in good agreement with those obtained for shot peened surfaces of ductile material [16,17,19] tive coating on crack initiation and found that the conversion of a tensile residual stress to a compressive one improved significantly the crack initiation stage and even inhibited the pre-existing small cracks from propagating [1].…”

Section: Contribution Of Residual Stresssupporting

confidence: 90%

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Low cycle fatigue life improvement of AISI 304 by initial and intermittent wire brush hammering

Makhlouf¹,

Sidhom²,

Khlifi³

et al. 2013

Materials & Design (1980-2015)

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The effects of hammering by wire brush as a method of improving low cycle fatigue life of highly ductile austenitic stainless steel AISI 304 have been investigated through an experimental study combining imposed strain fatigue tests and assessment of surface characteristic changes under cyclic loading by SEM examinations and XRD analysis. It has been shown that the fatigue life of wire brush hammered surface was increased by 307% at an imposed strain rate of 0.2% and only 17% at an imposed strain rate of 0.5%, comparatively to the turned surface. This increase in fatigue life is explained in terms of fatigue damage that is related to crack networks characteristics and stability which are generated during fatigue on both turned and wire brush hammered surfaces. The improvement of brushed surface is attributed to the role of the surface topography, the near surface stabilized compressive residual stresses and superficial cold work hardening on the fatigue crack network nucleation and growth. It is found that wire brush hammering produces a surface texture that favors, under cyclic loading, nucleation of randomly dispersed short cracks of the order of 40 lm in length stabilized by the compressive residual stress field that reached a value of r 0 = À749 MPa. In contrast, turned surface showed much longer unstable cracks of the order of 200 lm in length nucleated in the machining groves with high tendency to propagate under the effect of tensile residual stress field that reached value of r 0 = 476 MPa. This improvement is limited to strain rates lower than 0.5%. At higher strain rates, a cyclic plastic deformation induced martensitic phase alters furthermore the fatigue behavior by producing high cyclic strengthening of the bulk material. This phenomenon lead to a reduction in strain imposed fatigue life. It has also been established that wire brush hammering can be used as an onsite surface treatment to improve the residual fatigue life of components subjected to cyclic loading. The efficiency of this treatment is demonstrated if it is performed at a fraction of service lifetime N i /N r lower than 0.5.

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Section: Contribution Of Surface Strain Work Hardeningsupporting

confidence: 91%

Section: Contribution Of Residual Stresssupporting

confidence: 90%

Low cycle fatigue life improvement of AISI 304 by initial and intermittent wire brush hammering

Makhlouf¹,

Sidhom²,

Khlifi³

et al. 2013

Materials & Design (1980-2015)

View full text Add to dashboard Cite

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“…-Simple treatments such as conventional shot peening (CSP) [1][2][3][4][5][6], hammer peening (HP) [7,8] low plasticity burnishing (LPB) [9], deep-rolling (DR) [10], laser peening (LP) [11,12], ultrasonic peening [13] and pulsed electron beam treatments [14] were performed for steels, aluminum alloys and titanium alloys.…”

Section: Introductionmentioning

confidence: 99%

Potential fatigue strength improvement of AA 5083-H111 notched parts by wire brush hammering: Experimental analysis and numerical simulation

et al. 2014

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The effects of milling as machining process and a post-machining treatment by wire-brush hammering, on the near surface layer characteristics of AA 5083-H111 were investigated. Surface texture, work-hardening and residual stress profiles were determined by roughness measurement, scanning electron microscope (SEM) examinations, microhardness and X-ray diffraction (XRD) measurements. The effects of surface preparation on the fatigue strength were assessed by bending fatigue tests performed on notched samples for two loading stress ratios R 0.1 and R 0.5. It is found that the bending fatigue limit at R 0.1 and 10 7 cycles is 20% increased, with respect to the machined surface, by wire-brush hammering. This improvement was discussed on the basis of the role of surface topography, stabilized residual stress and work-hardening on the fatigue-crack network nucleation and growth. The effects biaxial residual stress field and surface workhardening were taken into account in the finite element model. A multi-axial fatigue criterion was proposed to predict the fatigue strength of aluminum alloy notched parts for both machined and treated states.

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“…These fusion processes are characterized by large temperature values that exceed the material melting temperatures, affecting distortion and residual stress states that must be controlled in order to assure the proper geometrical and stress characteristics of the final assembled part. It should be observed that several authors investigated the effects of the fusion welding operations on the obtained T-joints and lap and tried to determine the most effective process parameters to be used in order to reduce both distortions and residual stresses in the welded part [6][7][8][9]. Actually a strong improvement in the welding technology of such materials was obtained at the beginning of the nineties with friction stir welding (FSW), a solid state welding process, patented at TWI, in which a specially designed rotating tool characterized by a shaped pin-end is inserted into the adjoining edges of the sheets to be welded with a proper tilt angle and then moved along the joint.…”

Section: Introductionmentioning

confidence: 99%

Friction stir welding of tailored joints for industrial applications

2009

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Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the workpieces are welded together in a solid-state joining process at a temperature below the melting point of the workpiece material under a combination of extruding and forging. Since its invention in 1991 by TWI, such process has been reaching a continuously increasing popularity among aerospace, automotive and shipbuilding industries due its capability to weld unweldable or difficult-to-weld light alloys in different joint morphologies. In this paper a wide experimental campaign is carried out in order to obtain T and lap joints characterized by dimensions of industrial interest from two sheets, the stringer and the skin, of different materials. In particular a peculiar clamping fixture has been designed in order to assure a perfect contact between the stringer and the skin and to develop the "transparency" welding; a proper welding tool has been utilized allowing to obtain at the same time a sound joint and the designed final component fillet radii. Finally T-pull tests together with macro and micro observations have been developed at the varying of the main process parameters.

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Fatigue Life Evaluation of Shot Peened Al-Alloys 5083 H11 T-Welded Joints by Experimental and Numerical Approaches

Cited by 12 publications

References 7 publications

Low cycle fatigue life improvement of AISI 304 by initial and intermittent wire brush hammering

Low cycle fatigue life improvement of AISI 304 by initial and intermittent wire brush hammering

Potential fatigue strength improvement of AA 5083-H111 notched parts by wire brush hammering: Experimental analysis and numerical simulation

Friction stir welding of tailored joints for industrial applications

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