Quantitative determination of contact depth during spherical indentation of metallic materials—A FEM study

Effective indenter radius and frame compliance in instrumented indentation testing using a spherical indenter

“…The flow properties of SKH51, SUS440, S45C, and Al6061 were evaluated by a representative stress-strain approach by 10 partial unloadings at maximum indentation depth 100 mm and a loading rate of 1 mm/min. [17][18][19][20] Flow properties of the materials were also measured in uniaxial tension tests using an Instron 5582 (Instron, Norwood, MA) at a cross-head rate of 1 mm/min. To directly measure plastic pileup in the standard-hardness block, three-dimensional (3D) profiles of the residual indentation marks at various indentation depths between 10 and 100 mm were directly observed by 3D surface profiler (SIS series; SNU Precision, Seoul, Korea) with a depth resolution of 0.1 nm.…”

“…In IIT, elastic modulus (a measure of resistance to elastic deformation) and hardness (a measure of resistance to plastic deformation) are generally evaluated by analyzing the indentation load-depth curve without observing the residual indentation marks. 3 IIT has also been applied to evaluate flow properties, [17][18][19][20][21][22][23][24][25][26][27][28][29][30] residual stress, [31][32][33] and fracture toughness. [34][35][36][37] Corrections for imperfect indenter geometry and frame compliance play a critical role in the accuracy of IIT, because the real indenter geometry is not ideal and the measured displacement is not the same as the penetration depth of indenter due to frame compliance when the instruments do not use the surface reference for depth sensor.…”

“…41 Evaluating tensile properties by determining representative stress-strain points is a good example of the use of a spherical indenter at small scales. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] However, spherical indenters are not frequently used at micro-and nanoscales not only because of the difficulty in manufacturing spherical indenters at this scale but also because of the lack of methods for correcting for imperfect indenter geometry and frame compliance.…”

Conventional Vickers and true instrumented indentation hardness determined by instrumented indentation tests

“…The fundamental advantage of instrumented indentation testing (IIT) over conventional hardness testing is that mechanical properties such as elastic modulus, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] tensile properties, [16][17][18][19][20][21][22][23][24][25][26][27][28][29] and hardness can be measured by analyzing the indentation force-depth curve and without observing the residual indentation marks. However, elastoplastic deformation of materials around the indenter, i.e., plastic pileup or sink-in, [30][31][32][33][34][35][36][37] makes it difficult to determine the true contact depth in the loaded state.…”

Wear Transition of CrN Coated M50 Steel under High Temperature and Heavy Load

“…Kim et al [21] studied the actual contact depth during spherical indentation of many kinds of tool steels. According to his study, the elastic contact depth, h c *, and the pile-up depth, h p *, could be expressed as:…”