PAPERS & REPORTS

Introduce technical papers and reports of IIT (Instrumented Indentation Technology) and correlated fields.

 

 

Title

A Method for Estimating

Uncertainty of Indentation Tensile Properties in Instrumented Indentation Test

Author

Eun-chae Jeon

Division of Nano-Mechanical Systems, Korea Institute of Machinery & Materials, Daejeon, 305-343, Korea

e-mail:

Joo-Seung Park

Technology & Standards Policy Division, Korea Agency for Technology and Standards, Gwacheon, 427-723, Korea

e-mail:

Doo-Sun Choi

Division of Nano-Mechanical Systems, Korea Institute of Machinery & Materials, Daejeon, 305-343, Korea

e-mail:

Kug-Hwan Kim

e-mail:

Dongil Kwon

e-mail:

School of Materials Science and Engineering, Seoul National University, Seoul, 151-742, Korea

Press and Date of publication

Journal of Engineering Materials and Technology

Transactions of the ASME

JULY 2009, Vol. 131

Abstract

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.

_DOI: 10.1115/1.3120391_

Keywords: instrumented indentation test, uncertainty, indentation tensile property