Enhancement of the residual stresses of cold full‐forward extruded parts by application of an active counter punch

Hoche, Holger; Balser, Adrian; Oechsner, Matthias; Franceschi, Alessandro; Groche, Peter

doi:10.1002/mawe.201900050

Cited by 12 publications

(17 citation statements)

References 9 publications

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“…230 HV 0.1. This coincides with the literature values of 151.4 HV 0.3 for 1.4307 and 143.3 HV 0.3 for 1.4404 in the annealed state [7]. It is of note that the decay of the hardness is roughly exponential.…”

Section: Section III Unetchedsupporting

confidence: 92%

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Formation of residual stresses in austenitic stainless steels by infeed and recess rotary swaging

Hoche¹,

Jaeger²,

Franceschi³

et al. 2020

Preprint

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The austenitic stainless steels 1.4307 and 1.4404 significantly benefit from cold forming, due to their high work hardening capability. Great potential to improve the component's fatigue properties is expected by optimizing the forming process chain such that specific residual stresses are induced in critical component areas. In this work, an analysis of the formation of residual stresses during rotary swaging is carried out. Through this incremental forming process, high strain hardening and a complex material flow history are induced in the workpieces. Therefore, measuring strategies for the residual stress measurement of cold de-formed austenitic steels by X-Ray diffraction, using the sin2Ψ-method, were developed. Here, especially the 1.4307 is a challenging material due to cold forming induced martensite formation. Despite phase changes, both cold formed materials exhibit anisotropic microstructures as well as coarse grained areas. Moreover, particular notched geometries are produced on the workpieces by rotary swaging. The measuring techniques are further developed for these complex geometries and the residual stresses are investigated.

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Section: Section III Unetchedsupporting

confidence: 92%

“…Section III Section I Figure 6: Microstructure analysis by optical microscopy of sections I and III, V2A-etchant. The initial micrographs can be seen in [7].…”

Section: X 500x 50x 500xmentioning

confidence: 99%

Formation of residual stresses in austenitic stainless steels by infeed and recess rotary swaging

Hoche¹,

Jaeger²,

Franceschi³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Here, the tensile residual stresses on the surface in the steady-state region are reduced from about 750 to about 200 MPa with a constant counter-force of 80 kN. These results were validated by X-Ray diffraction measurements and similar results were obtained for the material 1.4404 [45]. Looking at Fig.…”

Section: Alternative Process Executionsupporting

confidence: 80%

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 further research in this direction, it is important that residual stress measurements on the surface are reproducible both at the same position as well as for varied measurement positions. The change of the residual stress state of austenitic steels shaped by cold extrusion at various depths has been researched extensively [5,6]. From the surface to depths of 1 mm, changes in the residual stress up to 800 MPa have been observed.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is imperative to gain reliable information from measurements at the surface. Research about optimizing the measurement parameters for the difficulties caused by coarsegrained microstructures has already been conducted [5]. In this research, it was shown that the worsening of measurement results by coarse grain effects can be alleviated by choosing a longer exposure time, introducing oscillation and φ-rotation, or utilizing a collimator with a bigger diameter.…”

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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Enhancement of the residual stresses of cold full‐forward extruded parts by application of an active counter punch

Cited by 12 publications

References 9 publications

Formation of residual stresses in austenitic stainless steels by infeed and recess rotary swaging

Formation of residual stresses in austenitic stainless steels by infeed and recess rotary swaging

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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