Investigations on residual stress generation in full-forward-extrusion

Landkammer, Philipp; Jobst, Andreas; Kiener, Christoph; Steinmann, Paul; Merklein, Marion

doi:10.1007/s11740-019-00892-5

Cited by 7 publications

(14 citation statements)

References 11 publications

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“…This expectation was confirmed in Ref. [15], where constant axial and tangential residual stresses were observed between 8 mm from the shoulder and 5 mm from the tip in non-ejected parts. The ejection from the die after forming results in the residual stress state shown in Fig.…”

Section: Parametersupporting

confidence: 66%

“…Young's modulus, Poisson's ratio and the initial yield stress were set to, E = 210000 MPa, ν = 0.28 and σ y = 263.74 MPa, in accordance with Ref. [15]. The four-dimensional set of remaining parameters for calibration was x = R ∞ b C γ .…”

Section: Fig 1 Cyclic Plastification Testsmentioning

confidence: 99%

“…appropriateness of the spatial discretization (FE-mesh) with respect to forming procedure (viz. process adopted mesh [15] and remeshing) and, moreover, ability of the employed constitutive model to accurately describe the Bauschinger as well as transient effects that are typically encountered in forming.…”

Section: Introductionmentioning

confidence: 99%

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Towards an holistic account on residual stresses in full-forward extruded rods

et al. 2021

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An holistic view is attempted towards prediction of the effect of residual stresses induced by full-forward extrusion on fatigue life of workpieces during operation. To study the effect of constitutive model on the accuracy of forming simulations, a combined nonlinear isotropic/kinematic hardening model as well as the isotropic hardening part of the same model are calibrated based on five compression-tension-compression uniaxial stress experiments. A full-forward extrusion finite element model is developed adapting both the aforementioned hardening plasticity models and the predicted residual stress states at the surface of the workpiece are compared against that of a corresponding forming experiment. Results show residual stress predictions of remarkable accuracy by the FE-models with the isotropic hardening model. The effect of residual stresses on fatigue life of the workpiece is qualitatively studied by uncoupled multiscale simulations featuring gradient crystal plasticity at the microscale. While the effective (homogenized) macroscale response indicates elastic response during a macroscopically cyclic loading, plasticity accompanying reduction of residual stresses is still present at the microscale within, e.g. grain boundaries.

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Section: Parametersupporting

confidence: 66%

Section: Fig 1 Cyclic Plastification Testsmentioning

confidence: 99%

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Towards an holistic account on residual stresses in full-forward extruded rods

et al. 2021

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“…Also, the FE models employed in the literature for the prediction of the residual stresses in cold forming usually neglect the temperature effects, e.g. [25]. As a result, the control of the process temperature is not a promising strategy to follow during cold forming.…”

Section: Strategies For the Manipulation Of Residual Stressesmentioning

confidence: 99%

Strategies for residual stress adjustment in bulk metal forming

et al. 2021

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The family of bulk forming technologies comprises processes characterised by a complex three-dimensional stress and strain state. Besides shape and material properties, also residual stresses are modified during a bulk metal forming process. The state of residual stresses affects important properties, like fatigue behaviour and corrosion resistance. An adjustment of the residual stresses is possible through subsequent process steps such as heat treatments or mechanical surface modification technologies, like shot peening and deep rolling. However, these additional manufacturing steps involve supplementary costs, longer manufacturing times and harmful effects on the product quality. Therefore, an optimized strategy consists in a targeted introduction of residual stresses during the forming processes. To enable this approach, a fundamental understanding of the underlying mechanisms of residual stress generation in dependence of the forming parameters is necessary. The current state of the art is reviewed in this paper. Strategies for the manipulation of the residual stresses in different bulk forming processes are classified according to the underlying principles of process modification.

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“…For cold extruded samples with cylindrical geometry, the measurement position can vary in two ways: by the length along the sample and the angle along the circumference. Regarding the length along the sample, measurements have been performed on ferritic steels [7]. In those, the scatter spanned up to 200 MPa.…”

Section: Introductionmentioning

confidence: 99%

Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

et al. 2021

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Cold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

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Investigations on residual stress generation in full-forward-extrusion

Cited by 7 publications

References 11 publications

Towards an holistic account on residual stresses in full-forward extruded rods

Towards an holistic account on residual stresses in full-forward extruded rods

Strategies for residual stress adjustment in bulk metal forming

Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

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