Indentation Plastometry of Very Hard Metals

Campbell, Jimmy; Gaiser-Porter, Marcus; Gu, Wenchen; Ooi, S. W.; Burley, Max; Dean, James; Clyne, T.W.

doi:10.1002/adem.202101398

Cited by 20 publications

(18 citation statements)

References 17 publications

(17 reference statements)

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“…Converted plots for compression have been obtained both by using the equations and via an inverse FEM method, changing the plasticity parameters in the Voce law until optimum agreement is reached between the measured nominal curve and the outcome of the FEM simulation of the test. This was done using a friction coefficient value of 0.15, which is broadly in line with the outcome of previous work [24] for these conditions (with no lubrication).…”

Section: Compressive Testingmentioning

confidence: 80%

Effect of Relatively Low Levels of Porosity on the Plasticity of Metals and Implications for Profilometry‐Based Indentation Plastometry

Reiff-Musgrove¹,

Gu²,

Campbell³

et al. 2022

Adv Eng Mater

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Herein, the effect of dispersed (relatively low levels of) porosity within a metal on its plastic deformation is examined. Stainless steel samples, made via additive manufacturing, are used in the work. It's found that porosity reduces stress levels during yielding and work hardening, approximately in proportion to the pore content. There is no significant difference between the strength of the effect during tension and compression, although porosity does reduce the tensile ductility. Finally, the profilometry‐based indentation plastometry (PIP) methodology (for obtaining stress–strain curves from indentation testing) are used. Porosity tends to bring the inferred yield stress down more strongly than during tensile testing and give higher initial rates of work hardening. This is associated with high local strains near the indenter causing closure of pores, so that volume is not conserved during the test. The resultant reduction in the pile‐up around the indent creates errors in the inferred stress–strain curve.

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Section: Compressive Testingmentioning

confidence: 80%

Effect of Relatively Low Levels of Porosity on the Plasticity of Metals and Implications for Profilometry‐Based Indentation Plastometry

Reiff-Musgrove¹,

Gu²,

Campbell³

et al. 2022

Adv Eng Mater

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“…This led to nominal stress–nominal strain curves, which could be compared with the corresponding experimental plots. The value used for the friction coefficient was obtained by comparing [ 4 ] measured and modeled barrelling profiles along the length of the sample after the test.…”

Section: Methodsmentioning

confidence: 99%

“…[1] Integrated facilities are now available that allow stress-strain curves to be inferred from a single indentation experiment within a timescale of a couple of minutes or so. Recent papers cover in detail several relevant topics, including the effects of material anisotropy [2] and residual stresses, [3] and application of the methodology to very hard metals [4] and relatively thin layers. [5] In general, the fidelity of PIP-derived stress-strain curves, when compared with those obtained via conventional tensile testing, is very good.…”

Section: Introductionmentioning

confidence: 99%

Indentation Plastometry of Welds

Gu¹,

Campbell²,

Tang

et al. 2022

Adv Eng Mater

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This investigation concerns the application of the profilometry‐based indentation plastometry (PIP) methodology to obtain stress–strain relationships for material in the vicinity of fusion welds. These are produced by The Welding Institute (TWI), using submerged arc welding to join pairs of thick steel plates. The width of the welds varies from about 5 mm at the bottom to about 40–50 mm at the top. For one weld, the properties of parent and weld metal are similar, while for the other, the weld metal is significantly harder than the parent. Both weldments are shown to be approximately isotropic in terms of mechanical response, while there is a small degree of anisotropy in the parent metal (with the through‐thickness direction being slightly softer than the in‐plane directions). The PIP procedure has a high sensitivity for detecting such anisotropy. It is also shown that there is excellent agreement between stress–strain curves obtained using PIP and via conventional uniaxial testing (tensile and compressive). Finally, the PIP methodology is used to explore properties in the transition regime between weld and parent, with a lateral resolution of the order of 1–2 mm. This reveals variations on a scale that would be very difficult to examine using conventional testing.

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“…Profilometry-based indentation plastometry (PIP) is a recently developed indentation-based approach with growing research activity (Campbell et al, 2018(Campbell et al, , 2019(Campbell et al, , 2021Burley et al, 2021;Tang et al, 2021;Gu et al, 2022). The technique has been shown to support prediction of bulk tensile specimen response for many ductile metals (Campbell et al, 2019(Campbell et al, , 2022Tang et al, 2021;Gu et al, 2022). Crucially, PIP's FEM-based fitting procedure reproduces the indentation profile, rather than a loaddisplacement curve, thus mitigating the identifiability problem (i.e.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty Quantification of a High-Throughput Profilometry-Based Indentation Plasticity Test of Al 7075 T6 Alloy

et al. 2022

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The quantification of spatially variable mechanical response in structural materials remains a challenge. Additive manufacturing methods result in increased spatial property variations—the effect of which on component performance is of key interest. To assist iterative design of additively manufactured prototypes, lower-cost benchtop test methods with high precision and accuracy will be necessary. Profilometry-based indentation plastometry (PIP) promises to improve upon the instrumented indentation test in terms of the measurement uncertainty. PIP uses an isotropic Voce hardening model and inverse numerical methods to identify plasticity parameters. The determination of the baseline uncertainty of PIP test is fundamental to its use in characterizing spatial material property variability in advanced manufacturing. To quantify the uncertainty of the PIP test, ninety-nine PIP tests are performed on prepared portions of a traditionally manufactured Al 7075 plate sample. The profilometry data and the Voce parameter predictions are examined to distinguish contributions of noise, individual measurement uncertainty, and additional set-wide variations. Individual measurement uncertainty is estimated using paired profilometry measurements that are taken from each indentation. Principal component analysis is used to analyze and model the measurement uncertainty. The fitting procedure used within the testing device software is employed to examine the effect of profile variations on plasticity predictions. The expected value of the error in the plasticity parameters is given as a function of the number of tests taken, to support rigorous use of the PIP method. The modeling of variability in the presence of measurement uncertainty is discussed.

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Indentation Plastometry of Very Hard Metals

Cited by 20 publications

References 17 publications

Effect of Relatively Low Levels of Porosity on the Plasticity of Metals and Implications for Profilometry‐Based Indentation Plastometry

Effect of Relatively Low Levels of Porosity on the Plasticity of Metals and Implications for Profilometry‐Based Indentation Plastometry

Indentation Plastometry of Welds

Uncertainty Quantification of a High-Throughput Profilometry-Based Indentation Plasticity Test of Al 7075 T6 Alloy

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