Instrumented Indentation System (I2S)
The MPM I2S is used to measure uniaxial yield stress (YS), ultimate tensile strength (UTS), and Brinell hardness (BHN) from a non-destructive surface indentation. It can be used to quickly and cost-effectively test in-service components and structures and it can be used in the laboratory for routine testing. One significant advantage is that the method does not involve machining of a test specimen, such as a tensile specimen. The test data are simply acquired by indentation loading. The I2S applies the load, acquires the data, and provides results in less than thirty seconds. Several example applications follow.
Application to In-service Components and Structures
The I2S is being used to measure tensile properties of buried pipe to assess the effects of aging. The I2S can also be used to measure localized tensile data in cases where damage has occurred as in railroad tank car collisions or bridge structure damage.
Application to Steel Plate Mills
Steel plate is often produced from rolls requiring oxide breaking and shear cutting after thermomechanical treatment. The I2S is being used in real-time on the production line to measure the tensile properties and optimize these variables plate-by-plate.
The I2S can be used in routine laboratory tensile data measurement and Brinell testing. The I2S offers significant advantages over conventional Brinell testing which involves optical measurement of the indentation diameter. Material ploughing and sinking-in effects often do not provide a definitive boundary for accurate diameter measurement. The I2S, on the other hand, has superior accuracy because the BHN is determined solely from applied load and deflection data.
ASTM Standards and Precision
The MPM I2S fully satisfies ASTM Standard E2546, “Instrumented Indentation Testing,” and the applicable portions of ASTM Standard E10, “Brinell Hardness of Metallic Materials.” The Brinell measurements made with the I2S are within the precision data reported in E10. Further, it has been demonstrated that the I2S equipment yields data that are consistent with the scatter in uniaxial tensile measurements (ASTM E8). For example, data for a single A36 steel alloy resulted in an uncertainty of about 5 ksi at the 99 % confidence interval whether it is measured by uniaxial E8 testing or by the I2S indentation test.