Effect of Crystallographic Orientation on Hardness and Indentation Modulus in Austenitic Stainless Steel

2013 ◽  
Vol 586 ◽  
pp. 31-34 ◽  
Author(s):  
Petr Haušild ◽  
Aleš Materna ◽  
Jiri Nohava
Keyword(s):  
Stainless Steel ◽  
Crystallographic Orientation ◽  
Indentation Test ◽  
Indentation Load ◽  
Indentation Modulus ◽  
Instrumented Indentation ◽  
Depth Of Penetration ◽  
Indentation Method ◽  
Electron Back Scattered Diffraction ◽  
Instrumented Indentation Test

The most commonly used method for the analysis of instrumented indentation test (Oliver-Pharr) is based on isotropic elastic solution of contact problem which is not necessarily valid when indenting at the scale of one (anisotropic) grain. In this paper, we performed the grid indentation method at the sub-micron scale (at low indentation load and depth of penetration) on an area containing several grains with different crystallographic orientation which was simultaneously characterized by electron back-scattered diffraction. Measured dependencies of hardness and indentation modulus on crystallographic orientation were compared with analytical solution and finite element simulations.

Instrumented Indentation Test

2011 ◽  
pp. 167-233
Author(s):  
C. Ullner
Keyword(s):  
Indentation Test ◽  
Indentation Load ◽  
True Stress ◽  
Test Method ◽  
Indentation Hardness ◽  
Instrumented Indentation ◽  
Hardness Testing ◽  
Scope Of Application ◽  
Instrumented Indentation Test

Abstract Instrumented indentation hardness testing significantly expands on the capabilities of traditional hardness testing. It employs high-resolution instrumentation to continuously control and monitor the loads and displacements of an indenter as it is driven into and withdrawn from a material. The scope of application comprises displacements even smaller than 200 nm (nano range) and forces even up to 30 kN . Mechanical properties are derived from the indentation load-displacement data obtained in simple tests. The chapter presents the elements of contact mechanics that are important for the application of the instrumented indentation test. The test method according to the international standard (ISO 14577) is discussed, and this information is supplemented by information about the testing technique and some example applications. The chapter concludes with a discussion on the extensions of the standard that are expected in the future (estimation of the measurement uncertainty and procedures for the determination of true stress-strain curves).

Analyzing the Influence of Test Force on Instrumented Indentation Test

2014 ◽  
Vol 685 ◽  
pp. 245-249
Author(s):  
Yang Liu ◽  
Rong Chen
Keyword(s):  
Test Data ◽  
Coefficient Of Variation ◽  
Indentation Test ◽  
Hardness Test ◽  
Relative Difference ◽  
Indentation Hardness ◽  
Indentation Modulus ◽  
Instrumented Indentation ◽  
Different Levels ◽  
Instrumented Indentation Test

For the problem that the value of test force will influence the result of instrumented indentation hardness test, the relation between test force and instrumented indentation hardness , indentation modulus were investigated. 55 groups of tests were carried out, in which the test force were divided to 11 different levels. On the basis of 110 test data, differences were analyzed and the relation curves were plotted by Origin. And the relative difference value was proposed. Results show that when 19.61N≤Fmax≤98.07N, the change of test force makes little influence on instrumented indentation test (IIT) results and coefficient of variation(CV); when 0.98N≤Fmax≤9.81N or 196.14N≤Fmax≤294.21N, the change of test force makes remarkable influence on IIT results and CV.

Nanohardness of Individual Phases in WC – Co Cemented Carbides

2013 ◽  
Vol 586 ◽  
pp. 23-26 ◽  
Author(s):  
Annamária Duszová ◽  
Radoslav Halgaš ◽  
Pavol Priputen ◽  
Marek Bľanda ◽  
Pavol Hvizdoš ◽  
...  
Keyword(s):  
Size Effect ◽  
Significant Influence ◽  
Crystallographic Orientation ◽  
Grain Orientation ◽  
Indentation Load ◽  
Cemented Carbides ◽  
Indentation Modulus ◽  
Instrumented Indentation ◽  
Load Size

The nanohardness of WC – Co hardmetals has been investigated using instrumented indentation and Berkovich tip indenter. The nanohardness, HIT, and indentation modulus, EIT, of Co phase and individual WC grains and the influence of their crystalographic orientation have been studied. SEM, AFM and EBSD methods were used for the characterization of the microstructures and indents and for the identification of crystallographic orientation of WC grains, respectively. Strong indentation load-size effect and significant influence of the crystallographic orientation of WC crystals on HIT and EIT have been found. The nanohardness of Co binder was approximately 10 GPa and that of WC grains varied between 25 and 50 GPa, depending on the grain orientation and load. The nanohardness values of the basal and prismatic planes of individual WC grains at load of 10 mN were 40.4 ± 1.6 GPa and 32.8 ± 2.0 GPa, respectively.

Evaluation of Tensile Properties Profile of Weld Zone Using Instrumented Indentation

2010 ◽  
Author(s):  
Seung-Kyun Kang ◽  
Young-Cheon Kim ◽  
Chan-Pyoung Park ◽  
Dongil Kwon
Keyword(s):  
Tensile Properties ◽  
Weld Zone ◽  
Indentation Test ◽  
Tensile Tests ◽  
Structural Safety ◽  
Small Scale ◽  
Stress And Strain ◽  
Instrumented Indentation ◽  
Deformation And Fracture ◽  
Instrumented Indentation Test

Understanding the property distribution in the weld zone is very important for structural safety, since deformation and fracture begin at the weakest point. However, conventional tensile tests can measure only average material properties because they require large specimens. Small-scale tests are being extensively researched to remove this limitation, among such tests, instrumented indentation test (IIT) are of great interest because of their simple procedures. Here we describe the evaluation of tensile properties using IIT and a representative stress-strain approach. The representative stressstrain method, introduced in 2008 in ISO/TR29381, directly correlates the stress and strain under the indenter to the true stress and strain of tensile testing by defining representative functions. Using this technique, we successfully estimate the yield strength and tensile strength of structural metallic materials and also obtain profiles of the weld-zone tensile properties.

A Method for Estimating Uncertainty of Indentation Tensile Properties in Instrumented Indentation Test

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Eun-chae Jeon ◽  
Joo-Seung Park ◽  
Doo-Sun Choi ◽  
Kug-Hwan Kim ◽  
Dongil Kwon
Keyword(s):  
Tensile Strength ◽  
Yield Strength ◽  
Tensile Test ◽  
Tensile Properties ◽  
Indentation Test ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Instrumented Indentation ◽  
Estimation Model ◽  
Instrumented Indentation Test

The instrumented indentation test, which measures indentation tensile properties, has attracted interest recently because this test can replace uniaxial tensile test. An international standard for instrumented indentation test has been recently legislated. However, the uncertainty of the indentation tensile properties has never been estimated. The indentation tensile properties cannot be obtained directly from experimental raw data as can the Brinell hardness, which makes estimation of the uncertainty difficult. The simplifying uncertainty estimation model for the indentation tensile properties proposed here overcomes this problem. Though the influence quantities are generally defined by experimental variances when estimating uncertainty, here they are obtained by calculation from indentation load-depth curves. This model was verified by round-robin test with several institutions. The average uncertainties were estimated as 18.9% and 9.8% for the indentation yield strength and indentation tensile strength, respectively. The values were independent of the materials’ mechanical properties but varied with environmental conditions such as experimental instruments and operators. The uncertainties for the indentation yield and tensile strengths were greater than those for the uniaxial tensile test. These larger uncertainties were caused by measuring local properties in the instrumented indentation test. The two tests had the same tendency to have smaller uncertainties for tensile strength than yield strength. These results suggest that the simplified model can be used to estimate the uncertainty in indentation tensile properties.

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