Critical strain of the sharp indentation through serration behavior with strain rate

Kami, Tsuyoshi; Yamada, Hitoshi; Ogasawara, Nagahisa

doi:10.1016/j.ijmecsci.2019.01.018

Cited by 1 publication

(5 citation statements)

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“…In agreement with the results obtained in a previous study [18], an increase in the value of the loading curvature after holding was observed at 293 and 343 K as a result of dislocation pinning caused by the diffusion of solute atoms into the dislocations. At 343 K, the GP zone formed inside the material as a result of aging.…”

Section: Temperature Of 293 and 343 Ksupporting

confidence: 92%

“…Therefore, there is a need to adopt such tests as an indentation test that can non-destructively evaluate the strength of a small area with accuracy comparable to that of uniaxial tests. In this study, we extend our previous work [8,18] to clarify the effects of testing temperature on the serration behavior during indentation tests. The microstructural changes in the Al-Zn-Mg-Cu alloy (7075 aluminum alloy) due to natural and artificial aging were employed [20].…”

Section: Introductionmentioning

confidence: 53%

“…The effective strain rates for the indentations were calculated using Equation ( 6). Herein, β = 0.1 was used, based on previous studies [8,18]; the effective strain rate-displacement relationship is shown in Figure 6. The effective strain rate under displacement rate control, given by Equation ( 6), decreased as the displacement increased.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies [8,18] indicated that the serration phenomenon in indentation could possibly be evaluated using the concept of effective strain rate. Indentation is performed using a sharp indenter, hence, a complicated deformation field is generated in the test material, whose deformation mechanism has only recently been clarified [19].…”

Section: Introductionmentioning

confidence: 99%

“…Indentation is performed using a sharp indenter, hence, a complicated deformation field is generated in the test material, whose deformation mechanism has only recently been clarified [19]. Through the indentation tests, it was also discovered that there is a test evaluation limit called critical strain [19] and that serrations could be used as an index to evaluate this effect [18]. However, these previous studies were conducted only in an ambient temperature environment, hence, the effect of temperature on the serration behavior during indentation was not investigated.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effects of Testing Temperature on the Serration Behavior of an Al–Zn–Mg–Cu Alloy with Natural and Artificial Aging in Sharp Indentation

Yamada

Kami

Ogasawara

2020

Metals

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Serration phenomena, in which stress fluctuates in a saw-tooth shape, occur when a uniaxial test is performed on an aluminum alloy containing a solid solution of solute atoms. The appearance of the serrations is affected by the strain rate and temperature. Indentation tests enable the evaluation of a wide range of strain rates in a single test and are a convenient test method for evaluating serration phenomena. Previously, the serrations caused by indentation at room temperature were clarified using strain rate as an index. In this study, we considered ambient temperature as another possible influential factor. We clarify, through experimentation, the effect of temperature on the serration phenomenon caused by indentation. An Al–Zn–Mg–Cu alloy (7075 aluminum alloy) was used as the specimen. The aging phenomenon was controlled by varying the testing temperature of the solution-treated specimen. Furthermore, the material properties obtained by indentation were evaluated. By varying the testing temperature, the presence and amount of precipitation were controlled and the number of solute atoms was varied. Additionally, the diffusion of solute atoms was controlled by maintaining the displacement during indentations, and a favorable environment for the occurrence of serrations was induced. The obtained results reveal that the variations in the serrations formed in the loading curvature obtained via indentation are attributed to the extent of interaction between the solute atoms and the dislocations.

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Section: Temperature Of 293 and 343 Ksupporting

confidence: 92%