Analysis of Surface Roughening in AA6111 Automotive Sheet Under Pure Bending

Shi, Yucai; Zhao, Ping; Jin, H.; Wu, Peidong; Lloyd, D. J.

doi:10.1007/s11661-015-3260-2

Cited by 23 publications

(20 citation statements)

References 17 publications

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“…The roughness was measured in the longitudinal direction (i.e., 2 as defined earlier) because, due to experiencing strain, this direction had greater roughness than the transverse direction. The arithmetic mean of the roughness, which has been reported to have a consistent relation with the surface deformation in the traditional forming processes [4][5][6][7][8][9], was determined using the following relation:…”

Section: Methodsmentioning

confidence: 99%

“…The arithmetic mean of the roughness adequately represents the effect of plastic deformation on free-surface roughening in the traditional forming processes [4][5][6][7][8][9]. Therefore, this measure was adopted in the current study.…”

Section: Influence Of Isf Strain On Free-surface Roughnessmentioning

confidence: 99%

“…The nature of correlation between the roughness and plastic strain has been a matter of debate in the metal forming processes, for it affects the modeling accuracy of a process. Some researchers claim a linear while others, depending on the type of process, claim a non-linear correlation [5][6][7][8]. In the ISF of Cu/Steel sheet, this correlation has been turned to be a non-linear, as defined by the following polynomial:…”

Section: Influence Of Isf Strain On Free-surface Roughnessmentioning

confidence: 99%

“…This free-surface roughness consequently promotes strain localization and leads to the premature failure of components during service [4,5]. Therefore, the production of smoother surfaces has been a matter of concern for the industrial and research community [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Past studies on traditional forming processes have revealed that the value of forming strain (s) applied on a sheet has a significant effect on the free-surface roughness and, further, the degree of this effect depends on the type of forming process [6][7][8][9]. The free surface in ISF experiences localized stretching and bending loads [18], as a result of which tensile stresses are imparted on the surface, potentially inducing defects (e.g.…”

Section: Introductionmentioning

confidence: 99%

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On the Free-Surface Roughness in Incremental Forming of a Sheet Metal: A Study from the Perspective of ISF Strain, Surface Morphology, Post-Forming Properties, and Process Conditions

Al‐Ghamdi

Hussain

2019

Metals

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Due to absence of any supporting die, the free surfaces in incremental sheet forming (ISF) experience uneven deformation. This results in rough surfaces, possibly leading to the reduced service life of components. Therefore, it is necessary to analyze and quantify the effects of the application of strain on the free-surface roughness. Moreover, in order to control roughness, both on the free surface and the opposite contact surface, the nature of correlation between the two types of roughnesses needs to be identified by classifying the significance of different process conditions. The present work is a fundamental study to address these points. A series of specimens are produced by subjecting a metallic sheet to a range of ISF strains (13% to 98%). These specimens are then subjected to a number of characterization tests, namely roughness, uniaxial tension, and residual stress tests. The results reveal that the mean free-surface roughness increases non-linearly as the normal strain (stretching + bending) on the free surface increases (where strain state on the surface is as follows: ɛ1 = 0, ɛ2 > 0, γmax = ɛ2 and 1 and 2 are principal directions). The roughness also increases, although linearly, with the post-forming sheet strength, residual stress, and forming force, thereby showing that strain hardening has a direct influence on the roughness in a way that sheet strengthening is achieved at the cost of surface quality. The surface morphology reveals that the free surfaces contained orange peel, slip lines, and micro-voids, with density increasing with strain application, thus indicating the possible influence of tensile stresses on free surface deformation and roughening at an increasing degree with strain. Further analysis of roughness results discloses that the free-surface roughness and the contact-surface roughness are inversely related, because the responses of the two to ISF processing were mutually exclusive. Based on the obtained results, future research directions are also discussed.

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