Formation of UFG-surface layers on a HSLA steel by a continuous Surface-SPD-Process

Kaune, Vanessa; Müller, Clemens

doi:10.1016/j.msea.2011.12.012

Cited by 18 publications

(11 citation statements)

References 14 publications

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“…The slope of the hardness increase at the flange tips, however, is independent of the depth. The same behavior is found in flanges produced by linear bend splitting and in the thinned area, apart from the decrease towards the tip . The constant properties found parallel to the split surface indicate the formation of a steady state in material flow within the process zone after the first few splitting steps.…”

Section: Manufacturing‐induced Propertiessupporting

confidence: 67%

“…For both materials, the yield strength close to the split surface estimated from these hardness values lies above the value measured in the tensile tests. The characteristic hardness gradient is found in all investigated materials and in profiles produced by both linear flow splitting and linear bend splitting [21,34], Figure 9. The increase in hardness at the flange surface b with respect to the material as delivered can be linked to the strain hardening behavior of the initial material, i.e.…”

Section: Strengthmentioning

confidence: 99%

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Manufacturing‐induced material properties of linear flow split and linear bend split profiles

Bruder

Ahmels

Niehuesbernd

et al. 2017

Materialwissenschaft Werkst

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In this work the two massive forming processes linear flow splitting and linear bend splitting, which generate profiles from sheet metal, are evaluated with respect to characteristic manufacturing‐induced material properties of the produced parts. Resulting microstructural features such as grain size and shape as well as crystallographic textures are linked to mechanical properties such as strength, ductility and anisotropic elasticity and general rules for their evolution are defined. Residual stress distributions are detailed and discussed with regard to the causing geometrical and forming process related aspects. The aim of this paper is to give a comprehensive overview of the properties of profiles produced by linear flow splitting and linear bend splitting and to illustrate general rules for their evolution in order to provide guidelines for an optimized product development process which allows a beneficial use of the manufacturing‐induced properties.

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Section: Manufacturing‐induced Propertiessupporting

confidence: 67%

Section: Strengthmentioning

confidence: 99%

Manufacturing‐induced material properties of linear flow split and linear bend split profiles

Bruder

Ahmels

Niehuesbernd

et al. 2017

Materialwissenschaft Werkst

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“…Neither the flange angle α nor the flange thickness sf or the sheet thickness s0 seem to have a strong effect on the resulting distribution of mechanical properties. For all LFS parameters and materials investigated in this work or previously [13,[20][21][22][23], the gradients are very similar exhibiting a steep decrease in hardness with increasing distance to the split surface to a depth of 300 to 500 µm and a flatter decrease or even constant hardness down to the lower side of the flange. This gradient correlates with a decrease in HAGB fraction and aspect ratio as well as an increase in grain size.…”

Section: Characteristic Properties In Lfs and Lbs Profilessupporting

confidence: 65%

“…The microstructural evolution during LFS and LBS as well as the characteristic distribution of local mechanical properties in the resulting profiles are very similar [20]. Therefore, the Table 1).…”

Section: Microstructures and Mechanical Propertiesmentioning

confidence: 65%

Integral sheet metal design via severe plastic deformation – state of the art and future challenges

Bruder

Kaune

Müller

2014

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The innovative forming processes Linear Flow Splitting (LFS) and Linear Bend Splitting (LBS) were developed to facilitate the continuous production of branched profiles with tailored sheet thickness by inducing severe plastic strain. In contrast to most SPD processes the stress state in LFS and LBS is very complex and plastic deformation is confined to limited volumes which results in steep strain gradients and consequently ultrafine grained (UFG) gradient microstructures. Even though the processes have been commercialized, the increased lightweight potential that originates from the local grain refinement remains mostly idle since it is neither fully understood nor easily assessable yet. The present work shows the state of the art for the LFS and LBS processes and compares the microstructures and distribution of mechanical properties for different steels processed with different LFS parameters. The data is used to identify characteristic manufacturing induced properties that are insensitive to processing parameters. Based on the experimental results a material flow model for the processing zone is proposed which is discussed with respect to the current understanding of plasticity at severe strains.Keywords: Surface Severe Plastic Deformation, Work Hardening, Linear Flow Splitting, Linear Bend Splitting, Gradient Microstructures IntroductionThe use of Severe Plastic Deformation (SPD) as top down approach to refine microstructures of metals and alloys to the submicron range has been investigated extensively during the last decades [1][2][3]. Aside from the scientific interest in fundamental research on plasticity phenomena at large strains, there is also a strong technological interest in these processes which is driven by the exceptional mechanical properties that are associated with the presence of ultrafine grained (UFG) microstructures [1]. Even though high strength materials are needed for a wide range of commercial applications where lightweight design is mandatory, the commercial success of SPD processes is rather limited so far [4]. The main reason for this are most likely the high processing costs of the predominantly discontinuous SPD processes but there is also a strong competition from materials based on modern alloy design and thermo-mechanical processing [5]. However, the Linear Flow Splitting (LFS) and Linear Bend Splitting (LBS) processes that are reviewed in the present paper demonstrate that UFG microstructures by SPD and commercial success in mass markets are no antagonisms. The LFS and LBS processes also referred to as split profiling and split bending have an exceptional position in the field of SPD. In contrast to conventional SPD processes their primary objective is not the generation of UFG microstructures while retaining the initial shape of the workpiece but the production of branched profiles from plain sheet metal [6][7][8]. However, since LFS and LBS induce severe strains under high hydrostatic compressive stresses they generate UFG microstructures by the same mechanisms [9]...

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“…Due to their superior properties, materials processed by means of SPD can be used for various applications e.g. in electrotechnics [4], automotive [5], aircraft [6], military [7], as well as in biomedicine [8,9]. SPD is for example suitable for production of high-strength electro-conductive copper [10], consolidation of nano-scaled Al-based composites [11,12], improvement of corrosion resistance of pure Mg [13], enhancement of hydrogen sorption capacity of Mg [14], decreasing the elastic modulus of Tibased biocompatible alloys [15], and increasing the corrosion resistance of bio-applicable Mg-based alloys [16,17].…”

Section: Introductionmentioning

confidence: 99%

Natural ageing of aluminium processed by twist channel angular pressing

Kunčická¹,

Kocich²

2017

Fifth International Conference on Advances in Civil, Structural and Mechanical Engineering - CSM 2017

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-The method of twist channel angular pressing (TCAP) was invented with the aim to increase the efficiency of single pass severe plastic deformation (SPD) technologies. The study shows the structure of TCAP-processed aluminium after processing and the changes developed in the structure after a year of natural ageing at room temperature. The grain refinement after a single pass TCAP was very significant due to effectively imposed shear strain; the majority of grains were smaller than 5μm. The grains further showed sub-structure featuring fine precipitates, accumulated dislocations and developed subgrains. Transmission electron microscopy of the one-year-aged samples showed increased precipitation; the precipitates acted as effective obstacles for grain growth and structure recovery. The microscopy results were supplemented with microhardness measurements, the results of which showed a significant hardening for the single pass TCAP, after which the average microhardness increased from 44.6 HV to more than 91 HV.

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Formation of UFG-surface layers on a HSLA steel by a continuous Surface-SPD-Process

Cited by 18 publications

References 14 publications

Manufacturing‐induced material properties of linear flow split and linear bend split profiles

Manufacturing‐induced material properties of linear flow split and linear bend split profiles

Integral sheet metal design via severe plastic deformation – state of the art and future challenges

Natural ageing of aluminium processed by twist channel angular pressing

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