Understanding the Friction Behavior of Niobium Sheets during Forming Processes

Silvestri, Alessia Teresa; Astarita, Antonello; Boccarusso, Luca; Carvalho, Alexandre Amorim; Durante, Massimo; Garlaschè, M.

doi:10.1007/s11665-020-04868-w

Cited by 5 publications

(4 citation statements)

References 38 publications

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“…FY,fr, results higher and more irregular for the dry sheet. This confirms the considerations on the variation of the friction coefficient from the results obtained in [27]. The dry sheets show galling; this phenomenon is a type of adhesive wear and it is caused by macroscopic transfer of material between metal surfaces during relative sliding motion.…”

Section: /4supporting

confidence: 87%

“…Moreover, other studies investigated the surface damages of Nb sheets during forming processes, like grinding marks, inclusions, galling phenomenon, orange peeling, tearing, scratches and wrinkling [25,26]. Precisely in order to better understand the friction behavior of Nb sheets during forming processes, the authors presented the results of an experimental campaign based on wear tests, carried out under different loads and in both dry and lubricated conditions [27]. These two different conditions are hereinafter referred to as "dry" and "lubricated".…”

Section: /1mentioning

confidence: 99%

“…In order to assess the influence of the tool/sheet contact conditions, the SPIF process was carried out in dry and lubricated conditions, in line with the preliminary pin-on-disk tests described in the Introduction section [27]; in particular, a thin layer of Reactolab industrial grease, applied with a brush on the sheet surface in contact with the forming tool, was used as lubricant.…”

Section: Spif Pr Spif Process Ocessmentioning

confidence: 99%

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Considerations on the Influence of the Tool/Sheet Contact Conditions for Incremental Forming of Niobium Sheets

Formisano¹,

Astarita²,

Boccarusso³

et al. 2021

Esaform 2021

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Niobium is a ductile transition metal of growing interest for several technological applications, thanks to its intriguing characteristics, among them high melting point, moderate density, good ductility, high corrosion resistance and superconductivity. By contrast, its use is limited by some weaknesses lied to the mechanical properties, which can undermine the quality of the surfaces worked by metal forming processes. Sheets of pure Niobium can be used for the manufacture of extremely customized components and a flexible process like the incremental sheet forming fits well with this manufacturing philosophy; in fact, this technique does not require complicated tools and/or dedicated equipment and is capable to respond quickly to the market demands. The scope of this paper is to investigate the influence of the tool/sheet contact conditions on different features like the forming loads, the surface quality and the occurrence of failures, when pure Niobium rolled sheets are formed incrementally. To this aim, the simplest variant of incremental sheet forming, namely single point incremental forming, was considered by using a common fixed end forming tool with hemispherical head. The process was carried out under dry and lubricated tool/sheet contact conditions, following the indications from a preliminary campaign of wear tests conducted by a pin-on-disk apparatus. The experimental campaign highlights the strong influence of the tool/sheet contact conditions and the importance of a correct choice of them on the features investigated, in order to limit the forming forces and the risk of failure, as well as to preserve the surface quality of the components made by incremental sheet forming of Niobium.

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Section: /4supporting

confidence: 87%

Section: /1mentioning

confidence: 99%

Section: Spif Pr Spif Process Ocessmentioning

confidence: 99%

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Considerations on the Influence of the Tool/Sheet Contact Conditions for Incremental Forming of Niobium Sheets

Formisano¹,

Astarita²,

Boccarusso³

et al. 2021

Esaform 2021

Self Cite

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“…The value of these components are influenced by the behaviour of tool and sheet and in particular, by assuming as rigid the tool, by the mechanical properties and the thickness of the sheet. On the other hand, F Y along wall A is influenced strongly by the tool/sheet contact conditions, so it results significantly lower under RB conditions (rolling friction; average value of about 80 N); the other two conditions (sliding friction) not only determine significantly higher force values (in line with the considerations on the friction coefficients reported in [40]; average value of about 350 N), but also show an irregular trend (in line with the results of a similar authors' study on another hard-to form material, i.e. the grade 1 titanium [8]), and both these aspects are more relevant for HT (dry) tests.…”

Section: Forming Forcessupporting

confidence: 77%

Formability and surface quality of non-conventional material sheets for the manufacture of highly customized components

et al. 2022

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In this work, incremental forming of pure niobium planar isotropic sheets was studied; in particular, two different types of test were conducted by varying the tool/sheet contact conditions, in order to understand the complex phenomena interesting this hard-to-form non-conventional material and to focus the attention on its formability and the finishing of the worked surfaces. From the tests, the formability limits were determined, the forming forces were acquired and analysed, the quality of the worked surfaces was evaluated with measures of roughness and high-magnification visual inspection, as well as the failures of the sheets were observed and interpreted. The results highlight that a proper choice of the contact conditions can avoid the occurrence of galling while preserving an optimal carrying out of the process. In any case, very good surface finishing and workability of niobium sheets, despite their brittle nature, is found when incrementally formed. As a consequence, incremental sheet forming of this non-conventional material can be considered a faisible way of manufacturing highly customized components.

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