Relation between vickers and rockwell hardness

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Discussion Overview

The discussion revolves around the relationship between Vickers and Rockwell hardness testing methods, focusing on finding a suitable approximation or formula to correlate the two hardness scales. Participants share their experiences with testing and seek advice on deriving equations based on empirical data.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant expresses the need for a formula linking Vickers and Rockwell hardness, mentioning their empirical data from over 50 specimens.
  • Another participant suggests that the conversion may depend on the material's hardness, providing links to various resources for hardness conversion.
  • A participant requests clarification on how to derive the formula using their test results, indicating a focus on polynomial relationships.
  • One reply proposes using existing data and performing a best fit to derive the equation, while also suggesting conducting both tests on the same specimens for better correlation.
  • Another participant inquires about the costs associated with renting hardness testers, indicating a practical aspect of their project.
  • Responses indicate that most labs purchase hardness testers rather than renting them, and suggest contacting manufacturers for quotes.
  • A participant mentions using polynomial equations for conversion and shares specific equations they found effective, inviting feedback on their accuracy compared to conversion tables.
  • Another participant acknowledges discrepancies with conversion tables and expresses interest in comparing results with others.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific formula or method for correlating Vickers and Rockwell hardness. Multiple approaches and equations are proposed, and some participants express differing experiences with conversion tables.

Contextual Notes

Participants note the dependence of hardness conversion on material properties and the potential for discrepancies in results when using conversion tables. There is also mention of the need for empirical testing to validate proposed equations.

Who May Find This Useful

Individuals involved in materials science, engineering, or hardness testing who are looking for methods to correlate different hardness scales or seeking practical information on hardness testing equipment.

borja
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I am doing my university project about the relation between vickers and rockwell hardness. I know that there is not a mathematical relation but I need to find a good approximation. I have practice both tests in more than 50 specimens (HV70-HV950) and I have more than 300 (HV1,HR1),(HV2,HR2),... points. Any idea how to find the relation? I have done some graphics and got their ecuation with excel but how can I know which is the best one, because I have more than seven different equations (logaritmic, polinomical, exponentials,...). Sorry about my english thanks
 
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The conversion will depend on the material (hard or soft) somewhat.

Hard - http://www.gordonengland.co.uk/hardness/hardness_conversion_2c.htm
Soft - http://www.gordonengland.co.uk/hardness/hardness_conversion_3c.htm

Or

http://www.hardnesstesters.com/hardness-conversion-high.htm
http://www.hardnesstesters.com/hardness-conversion-low.htm

Hardness conversion calculator - http://www.tribology-abc.com/calculators/hardness.htm
Standard Hardness Conversion for metals acc. ASTM E 140 - 97, September 1999, Conversion for Non-Austenitic Steels, Table 1.

A nice overview of hardness testing on steels - http://www.key-to-steel.com/Articles/Art140.htm
 
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I need the formula

Sorry did not express correctly. The aim of my project is to find the formula that links vickers and rockwell (example: HR=a(HV)^2+b(HV)+c). I have done tests using steel Which goes from HV170 to HV900. My question is: How can I get that formula using the values I got in my test?
Thanks for your interest Astronuc
 
borja, in your case, you could use the data provided in the links I provided and do a best fit between HV and appropriate HR data, and then apply that equation to your HV data to get the corresponding HR values.

Otherwise, you would have to do both Vickers and Rockwell tests on the same specimens, and from that develop a correlation as you mention.
 
renting prize

thank you very much for the information. I have already finished the investigation and I am doing the quote. I want to take in count all the expenses and I vave been trying to find how much costs to rent a vickers and rockwell hardness testers. I have sendt some e-mails to Canadian and french companies but They didn`t answer to me. Does anybody know it?
Thanks
 
I think one has to rely on the companies, since they are the one's who will give the quote (price). I have not heard of someone renting a hardness tester.

It seems that most academic and industrial labs buy such equipment.

Perhaps one could contact US and/or Japanese manufacturers as well.
 
Hi borja, have you found a formula for this conversion? Of course a polynomial equation could be the easier way to fit the data. I am also working with this conversion. I have used conversion tables but I had some discrepancies. Did you compare your results with these conversion tables?
Thank you and regards
 
Dear Dng,
Polynomial conversion is the easiest way for doing it, but I have found a better one:

HV = 7091,843768 / (125,6010596- HRB)
HV = 1974914,439/ (102,9783872- HRC)2 ---------- 20 < HRC < 40
HV = 15936,2268 / (79,13859914– HRC) ---------- HRC > 40


I have compared my results with conversion tables and I had very good results. Try this way and send a reply please, so I can know if it suits correctly with other values.
 
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