Nanoindentation as a strength probe—a study on the hardness dependence of indent size for fine-grained and coarse-grained ferritic steel

Miyahara, Kensuke; Matsuoka, Saburo; Hayashi, Tohru

doi:10.1007/s11661-001-0091-0

Cited by 14 publications

(21 citation statements)

References 16 publications

(15 reference statements)

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“…They investigated the hardness dependence of indent size by introducing a converted Vickers hardness. 12) They also revealed quantitatively the contribution of dislocation, solutes, block boundary and cementite to hardness in tempered martensitic steels used at room temperature by means of the same method. 13) By using the nanoindentation technique, Komazaki et al 14) reported that hardness inside lath grain decreases at the primary stage of creep deformation in 9Cr-0.5Mo-1.8W-VNb steel.…”

Section: Introductionmentioning

confidence: 91%

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Contribution of Microstructural Factors to Hardness Change during Creep Exposure in Mod.9Cr-1Mo Steel

et al. 2005

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The effect of microstructural factors on hardness was investigated in normalized, tempered, aged and crept materials for Mod.9Cr-1Mo steel, using nanoindentation and microhardness tests. Nanohardness and microhardness decreased during tempering, aging and creep exposure. Dislocation spacing, lath width, high angle boundary (block and packet boundary) spacing and inter-particle spacing increased during tempering, aging and creep exposure. A converted Vickers hardness was introduced to compare directly nanohardness and microhardness to Vickers hardness. The converted Vickers hardness increased with indent size in all the materials tested. Hardness at an indent size less than 1 mm mainly consists of dislocations inside lath grains. Hardness at an indent size larger than 1 mm originates from not only dislocation but precipitates and high angle boundaries such as block and packet boundaries. Comparing the converted Vickers hardness with lath width and high angle boundary spacing in normalized material with no precipitates, it was found that the lath boundary does not contribute to hardness. The difference in converted Vickers hardness between tempered and aged material was obviously large at the indent size, greater than inter-particle spacing. The decrease in hardness during aging is caused by increase in inter-particle spacing due to coarsening and coalescence of precipitates. On the other hand, not only changes in precipitates but also increase in high angle boundary spacing and dislocation spacing contribute to decrease in hardness during creep exposure.

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Section: Introductionmentioning

confidence: 91%

“…Miyahara et al 12) revealed the contribution of grain boundary to hardness in fine-grained ferritic steel by using a nanoindentation hardness system. They investigated the hardness dependence of indent size by introducing a converted Vickers hardness.…”

Section: Introductionmentioning

confidence: 99%

Contribution of Microstructural Factors to Hardness Change during Creep Exposure in Mod.9Cr-1Mo Steel

et al. 2005

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“…An AFM ultra micro-hardness tester with special levers developed by NIMS was utilized for testing the hardness at the nanoscale level [10][11][12][13]. In this study, two types of special levers with apical angles of 60 o and 115 o were used for the triangular pyramidal indenter.…”

Section: Methodsmentioning

confidence: 99%

“…An indentation test is one of the most common techniques used to extract the local material properties at the nano-, sub-micron-, and micron-scale [10][11][12]. In particular, nanoindentation combined with atomic force microscopy (AFM) is useful for evaluating the hardness of a specific nanoscale site in a material having complex microstructures, because an in-situ AFM image enables the accurate setting of a Berkovich indenter with a triangular pyramidal shape at the desired site [11].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, nanoindentation combined with atomic force microscopy (AFM) is useful for evaluating the hardness of a specific nanoscale site in a material having complex microstructures, because an in-situ AFM image enables the accurate setting of a Berkovich indenter with a triangular pyramidal shape at the desired site [11]. Furthermore, recently we have proposed a new method for measurement of Vickers hardness values in scales ranging from nano to micro levels in disk superalloy [13], making it possible to divide clearly the each strengthening factors.…”

Section: Introductionmentioning

confidence: 99%

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New Quantitative Analysis of Contributing Factors to Strength of Disk Superalloys

Osada¹,

Gu²,

Nagashima³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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The contributions of multiple strengthening factors to the 0.2% flow stress have been studied in a cast and wrought Ni-Co base disk superalloy with varying grain size, twin fraction and bimodal or trimodal ′ size distributions. The alloy was heat-treated within the ′ sub-and super-solvus temperature ranges between 1100 o C to 1180 o C, followed by two step aging heat-treatment. The contribution of each strengthening factor are analyzed by measuring its Vickers hardness at over a structural scale ranging from nano to micro levels and then by converting the hardness differences to the contribution to the 0.2% flow stress on the basis of the empirical relation:  0.2 =2.46Hv. The results clearly show that the contribution of grain boundary strengthening decreased and reached zero with increasing solution temperature. The behavior followed Hall-Petch effect and Zener's pinning model, and strongly depended on the size and volume fraction of pinning primary ′ that is un-dissolved during solution treatment. Meanwhile, the contributions of secondary and tertiary ′ precipitation strengthening increased with increasing temperature. The behaviors also strongly depend on the volume fraction of the primary ′ since the designed total volume fraction of ′ of the alloy is approximately 0.5. As a result, the combinations of these strengthening factors lead to the maximum flow stress at solution temperature of 1135 o C. This would suggest that the primary ′ plays an important role to optimize the microstructure combination through the solution heat-treatment.

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Synthesis and nanoindentation study of high-velocity oxygen fuel thermal-sprayed nanocrystalline and near-nanocrystalline Ni coatings

Ajdelsztajn

Chung

Lavernia

et al. 2002

Metall Mater Trans A

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In the present work, the nanoindentation technique was used to study the behavior of nanocrystalline Ni coatings. Two different types of Ni coatings were synthesized. One of the coatings was prepared with a commercial-grade Ni powder (as received, near-nanocrystalline), and the second coating was sprayed with the same powder, after having been mechanically milled in liquid nitrogen for 15 hours (nanocrystalline). Identical high-velocity oxygen fuel (HVOF) spray parameters were used for both types of coatings. The oxide-phase content in each coating was analyzed. The microstructure and properties of the milled powders and as-sprayed coatings were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nanoindentation. The average grain size of the as-received powder was 140 Ϯ 52 nm, and that of the as milled powders was 15.7 Ϯ 5.1 nm. The near-nanocrystalline coating microstructure was composed of grains with an average grain size of 280 Ϯ 39 nm, and the nanocrystalline coating was composed of nanocrystalline grains with an average grain size of 92 Ϯ 41 nm. The nanoindentation technique was applied to characterize the coating hardness under different penetration depths. The indentation size effect (or ISE) has been observed and correlated to the microstructure of the coatings. The results show that the assumption of geometrically necessary dislocations was valid for this study. A critical indentation depth was identified for measuring the intrinsic properties of the constituent material of the coating (Շ500 nm).

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Nanoindentation as a strength probe—a study on the hardness dependence of indent size for fine-grained and coarse-grained ferritic steel

Cited by 14 publications

References 16 publications

Contribution of Microstructural Factors to Hardness Change during Creep Exposure in Mod.9Cr-1Mo Steel

Contribution of Microstructural Factors to Hardness Change during Creep Exposure in Mod.9Cr-1Mo Steel

New Quantitative Analysis of Contributing Factors to Strength of Disk Superalloys

Synthesis and nanoindentation study of high-velocity oxygen fuel thermal-sprayed nanocrystalline and near-nanocrystalline Ni coatings

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