Surface Roughening and Microscopic Inhomogeneity of Polycrystalline Iron during Cyclic Plastic Deformation.

Shimizu, Ichiro; Terai, Hiroaki; Nosho, Takayoshi; Abe, Takeji

doi:10.1299/kikaia.64.1043

Cited by 2 publications

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“…It was reported that the crystal grains with high Schmid factor (i.e. low Taylor factor) deformed on a priority basis 43) for the low strain range. This result implies that the inhomogeneous deformations of polycrystalline grains are mainly effected by the initial crystal orientation rather than the work hardening difference in each crystal orientation for the insitu observation condition.…”

Section: In-situ Observation Of Surface Roughening Inmentioning

confidence: 99%

Effect of Microstructure on Surface Roughening in Stretch Forming of Steel Sheets

et al. 2017

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Surface quality is an important requirement in outer automobile panels, and to obtain products with an excellent surface quality the development of surface roughening during press forming should be prevented. However, the influence of microstructures on surface roughening is not yet sufficiently understood, and thus it is difficult to control surface roughening during press forming. In this study, the mutual effect of the development of texture and the surface profile variation is examined in detail using two types of tests: a Marciniak type test used for surface roughening observation, and a microscopic biaxial tensile test in a vacuum chamber of scanning electron microscope. The latter test enables in-situ continuous observations of microstructure evolution under biaxial deformation, which is a typical deformation mode in press forming. Interstitial free (IF) steel sheets are used in this study because these sheets are mainly used for outer panels. Results show that surface roughening becomes large for sheets which have a larger number of crystal grains with orientations in the vicinity of ND(001) due to inhomogeneous deformation derived from their lower deformation resistance. It is therefore suggested that surface quality after press forming may be further improved by reducing the number of grains with crystal orientation of ND(001) in IF steel sheets.

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Section: In-situ Observation Of Surface Roughening Inmentioning

confidence: 99%

Effect of Microstructure on Surface Roughening in Stretch Forming of Steel Sheets

et al. 2017

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“…The waveforms of these fine reliefs caused by PSBs typically have a wavelength of around 1 µm. In contrast, the wavelengths of convex and concave structure due to grain deformation are several times larger than grain size [6,7]. Thus, the wavelengths of surface relief due to grain deformation are much larger than those due to PSBs.…”

Section: Introductionmentioning

confidence: 92%

“…If the changes in the surface topography can be related to the amount of physical damage, it may be possible to estimate the degree of fatigue damage from measuring surface topography. During cyclic loading, two mechanisms cause the surface roughening of metallic materials: (a) formation of persistent slip bands (PSBs) [1][2][3][4][5] and (b) deformation of crystal grains [6,7]. In the PSBs, there are fine peaks and valleys, i.e., extrusions and intrusions caused by active slip systems.…”

Section: Introductionmentioning

confidence: 99%

Changing Mechanisms of Surface Relief and the Damage Evaluation of Low Cycle Fatigued Austenitic Stainless Steel

2018

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To quantitatively investigate the cause of the changes in arithmetic mean roughness Ra and arithmetic mean waviness Wa of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on persistent slip bands (PSBs) and crystal grain deformations was conducted on SUS316NG. During the fatigue tests, the specimen’s surface topography was regularly measured using a laser microscope. The surface topographies were analysed by frequency analysis to separate the surface relief due to PSBs from that due to grain deformation. The height caused by PSBs and that by grain deformation were measured respectively. As a result, both of the heights rose with the increase of usage factor (UF). The amount of increase in the heights with respect to UF increased with strain range. The trend of development of both heights was similar with the trend of Ra and Wa. A comparison between Ra and the height caused by PSBs showed that these values strongly correlated with each other. A comparison between Wa and the height caused by grain deformation also showed that these values strongly correlated with each other. Consequently, the surface texture parameters Ra and Wa represent the changes in the heights of surface reliefs due to PSBs and grain deformation.

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Surface Roughening and Microscopic Inhomogeneity of Polycrystalline Iron during Cyclic Plastic Deformation.

Cited by 2 publications

References 0 publications

Effect of Microstructure on Surface Roughening in Stretch Forming of Steel Sheets

Effect of Microstructure on Surface Roughening in Stretch Forming of Steel Sheets

Changing Mechanisms of Surface Relief and the Damage Evaluation of Low Cycle Fatigued Austenitic Stainless Steel

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