DEFINITION OF LOADING FOR HARDNESS BLOCKS |
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| Hiroshi Yamamoto, Takashi Yamamoto Hiroyuki Kawashima, Mikie Shibata |
- Abstract:
- In a previous report, the authors investigated changes in hardness measurements when load rise time (LRT) was changed over a broad range in Vickers harness tests with loads of between 15 kgf and 150 kgf. As a result, we reported that hardness measurements varied according to the LRT value for every test load, while they remained almost constant between 15 kgf to 150 kgf if LRT was the same, although the indentation velocity of the indenter differed by more than three times between the two loads. It is very interesting that the considerable difference in indentation velocity due to varied test loads was not reflected much in hardness measurements. We, therefore, verified the effects of loading speed on hardness measurements theoretically from the strain rates of indentation deformation under the indenter and obtained some findings as follows. (1) It is necessary to define loading conditions to ensure the reliability of hardness blocks (2) The loading condition, namely the strain rate under indentation could be determined by the equation which was newly introduced by the authors. (3) According to this equation, loading conditions for general harness tests could be defined by loading time (LRT) regardless of load values. (4) Also considering that hardness measurements can vary according to load holding time, we may say that testing conditions can be "defined by time,". (5) Consequently, from the viewpoint of industrial practice, it would be reasonable to have rough criteria, that is, for how many seconds the test should be conducted, rather than to have scrutinized discussions on indentation velocity.
- Keywords:
- Standard blocks, Loading speed, Indentation velocity, Strain rate
- Download:
- IMEKO-TC5-2004-026.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC5
- Event name:
- Hardness Measurements Theory and Application in Laboratories and Industries
- Title:
- 9th HARDMEKO 2004
- Place:
- Washington, DC, USA
- Time:
- 11 November 2004 - 12 November 2004