John Song, Sam Low and Li Ma
The National Institute of Standards and Technology (NIST) is developing Standard Reference Material (SRM) 2809 Rockwell Diamond Indenter to support Rockwell hardness standardization. Most tolerances of the SRM indenters are adopted from those of the calibration grade Rockwell indenters specified in ASTM and ISO standards except the form deviations from tip radius. Based on the historical data of geometrical measurements and hardness tests at NIST, and the results of FEA (Finite Element Analyses) simulations, a tight tolerance, ± 0.5 µm, is specified for the form deviations of the SRM...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Takashi Yamamoto, Kensuke Miyahara
The Rockwell hardness test is commonly used and accepted by many industrial users, but the hardness value requires conversion between scales because the geometry of the indenters and the load ranges are different. On the other hand, hardness calculation using pyramidal indenters is quite simple and can be applied to any load range, though it is much more complicated to calibrate the frame compliance and the truncation of indenters in nanoindentation measurement. For this reason, nanoindentation measurement is not yet fully industrially friendly. In order to improve the above situation, newly...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Alessandro Germak, Alfonso Liguori, Claudio Origlia
The Istituto Nazionale di Ricerca Metrologica (INRIM) and Galileo section of LTF S.p.a. have cooperated for many years in the field of hardness for developing and improving Primary Hardness Standards and measuring systems for their laboratories. With this experience, Galileo-LTF has realized many installations for several NMIs in the world. All these Hardness Standards and measuring systems have been metrologically characterised by INRIM. In the paper, experiences made during the metrological characterization will be shown. They include the methods and results of direct verification of...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Alessandro Germak, Claudio Origlia
Brinell hardness measurements are widely used at industrial level. For the calculation of Brinell hardness values, the measurement of the diameter of indentations is necessary. In practice, the measurement of the image created by the optical systems used for the magnification of the indentation is usually carried out. The dimension of the indentation image depends by the optical system that, in practice, transform the real indentation in image using properties of light reflection. The paper describe the effect of this influence parameter in Brinell hardness measurements in experiments...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Renato R. Machado, Sérgio P. de Oliveira, Claudio A. Koch, Islei D. da Silva, Bianca da C. O. Muniz
The objective of this work is to analyse and discuss the influence of the use of different numerical apertures (NA) and its magnification on the measurement of indentations on Vickers (HV) and Brinell (HB) hardness blocks previously certified. It was used a new reference Vickers and Brinell measurement system, recently installed and qualified at the Brazilian National Metrology Institute (Inmetro) by the National Institute of Metrological Research (iNRiM/Italy). The system used was a Galileo Galvision (LTF S.p.A., Italy) that carries out automatic measurements throughout two methods, the...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Li Ma, Sam Low, John Song
Significant measurement differences have been continually observed worldwide in Brinell hardness tests, even in the secondary calibration laboratories that calibrate test block reference standards. The main cause of this problem is the edge of the indentation is not a distinct boundary, but is instead a curved surface from either material piling up (pile-up) or sinking in (sink-in) caused by plastic flow of the material surrounding the ball indenter. This makes it difficult to clearly resolve the edge of the indentation and thus determine the indentation diameter. In this research, Brinell...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Samuel Low, Rodney Jiggetts
Since the mid 1990s, several factors have influenced the standards development organization ASTMInternational to make changes and additions to their published hardness test method standards. These factors included the advent of laboratory quality systems and the resulting need for uncertainty analysis; technological advances in testing equipment and measurement methods; and the recognition that improvement to the methods could be made. The result has been to improve the existing standards and develop new standards to meet evolving needs of industrial users. Some of the more important changes...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Rugkanawan Kongkavitool, Satoshi Takagi, Takashi Usuda
The non-uniformity of the hardness reference block is one of the important factors, which influence the hardness measurement. For calibration of hardness reference block, the elementary idea to reduce the error from this factor is to make the indentations at the distributed location as though covering the entire test surface with limited number of indentations. The principle to decide the appropriate numbers and locations of the measurement is to consider the trend and frequency of hardness distribution. “Stratified sampling” was introduced to the study on the assumption that the confidence...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Yusuke Yoshikawa, Shigeo Katayama, Satoshi Takagi, Tatsuya Ishibashi, Motofumi Ohki
Even though the efforts have been made to develop an ideal hardness testing machine, it is inevitable that the difference of performance between the models (or types) of testing machine significantly affect the test results especially in the range of nanoindentation. The hardness reference blocks can be used to compensate the unreliability of machines by evaluating the difference between machines. The performance of hardness reference blocks should be considered from various aspects, e. g., repeatability and uniformity of parameters such as HM or HIT, easy handling, durability of testing,...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
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Motofumi Ohki, Tatsuya Ishibashi, Jun Kinoshita, Hiroki Uchiyama
Thermal barrier coatings (TBCs) have been applied to vanes / blades of gas turbines for recent electric power stations and these contribute to the efficiency of gas turbines. Measurement of Young’s modulus of the top-coat of TBCs with high accuracy is important since it is a dominant factor for determining the magnitude of thermal stress. However, until now, evaluation method for Young’s modulus of the top-coat has not been established, due to difficulty of material testing in its coated form. Furthermore, a porosity of the top-coat is changed by progress of sintering phenomenon caused by...
Symposium on Recent Advancements in the Theory and Practice of Hardness Measurement
· TC5
· 2007
· Download