Aluminum alloys hardness measurement

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Discussion Overview

The discussion revolves around the comparison of Rockwell B and Rockwell E scales for measuring the hardness of aluminum alloys. Participants explore the applicability, accuracy, and practical considerations of each scale in the context of aluminum alloy testing.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that Rockwell B has a wider range of applicability based on test comparison data.
  • Others note that Rockwell B uses a 1/16" steel sphere at 100 kg, while Rockwell E uses a 1/8" steel sphere at the same load, which may influence the choice depending on specimen thickness.
  • A participant mentions a rule of thumb that the specimen thickness should be ten times the indentation penetration, indicating that Rockwell E may allow for measuring thinner specimens than Rockwell B.
  • Concerns are raised about the accuracy of converting between hardness scales, with some participants questioning the reliability of such conversions.
  • One participant references a source recommending limited use of Rockwell testing for aluminum, suggesting that Vickers or other methods may be better for obtaining convertible hardness values.
  • Another participant asserts that Rockwell B is a better option for measuring aluminum alloys.

Areas of Agreement / Disagreement

Participants express differing opinions on the suitability of Rockwell B versus Rockwell E for measuring aluminum alloys, with no consensus reached on which scale is definitively better.

Contextual Notes

Participants highlight various assumptions regarding specimen thickness and indentation penetration, as well as the limitations of hardness testing methods for aluminum alloys.

shushu97
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Hello

Rockwell B or Rockwell E - which one is better to measure the hardness of aluminum alloys?

Thank you!
 
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Rockwell B has a wider wide range of applicability judging by the test comparison data. Consider http://www.newageinstruments.com/problems-in-rockwell-testing.pdf
Test your given alloy and check the typical indentation- is it small compared to your thickness. Are the results repeatable? Of course Rockwell is not much good as descriptor of other properties so the scale is usually decreed by other considerations.
 
Thanks!
I know B is a wider scale but I am only interested in measuring aluminum alloys.
There is also a rule of thumb that the higher the load the better (B is 100 kg with 1/16" steel sphere compared to 100 kg with 1/8" steel sphere in E).
Another rule of thumb says the specimen thickness should be ten times the indentation penetration which is (130-Hardness number)/500 in mm. So E will enable me to measure thiner specimens than B.
I don't know how accurate the conversion between hardness scales really is.
 
Thanks!
I know B is a wider scale but I am only interested in measuring aluminum alloys.
There is also a rule of thumb that the higher the load the better (B is 100 kg with 1/16" steel sphere compared to 100 kg with 1/8" steel sphere in E).
Another rule of thumb says the specimen thickness should be ten times the indentation penetration which is (130-Hardness number)/500 in mm. So E will enable me to measure thiner specimens than B.
I don't know how accurate the conversion between hardness scales really is.
 
Rockwell B is a better option.
 

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