Relation between vickers and rockwell hardness

In summary, the conversation is about finding a formula that links Vickers and Rockwell hardness values. The individual has conducted tests on more than 50 specimens with values ranging from HV70 to HV950, and has also obtained over 300 points for HV1, HR1, HV2, HR2, etc. They have explored different equations such as logarithmic, polynomial, and exponential, but are unsure of which one is the best. They have researched conversion methods and websites, such as those from Gordon England and Hardness Testers, and have also reached out to Canadian and French companies for rental prices for Vickers and Rockwell hardness testers. They have found a formula that shows good results when compared to conversion tables, using HV values
  • #1
borja
4
0
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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  • #2
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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  • #3
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
 
  • #4
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.
 
  • #5
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
 
  • #6
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.
 
  • #7
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
 
  • #8
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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What is the difference between Vickers and Rockwell hardness?

Vickers and Rockwell hardness are both measures of a material's resistance to indentation, but they use different methods to determine the hardness value. Vickers hardness uses a diamond indenter to create an impression on the material's surface, while Rockwell hardness uses a steel ball or cone indenter. Additionally, Vickers hardness measures the diagonal length of the indentation, while Rockwell hardness measures the depth of the indentation.

How are Vickers and Rockwell hardness values related?

Vickers and Rockwell hardness values are not directly related, as they use different scales and methods to measure hardness. However, there are conversion tables available that can provide an approximate conversion between the two values.

Which method is more accurate, Vickers or Rockwell hardness?

Both Vickers and Rockwell hardness are considered to be accurate measures of a material's hardness. However, Vickers hardness is often preferred for softer materials and for more precise measurements, while Rockwell hardness is better suited for harder materials and larger testing areas.

What factors can affect the Vickers and Rockwell hardness values of a material?

The Vickers and Rockwell hardness values of a material can be affected by various factors, including the type and size of the indenter, the applied load, the surface condition of the material, and the temperature of the testing environment. It is important to carefully control these factors to ensure accurate and consistent hardness measurements.

How are Vickers and Rockwell hardness values used in materials science?

Vickers and Rockwell hardness values are commonly used in materials science to compare the hardness of different materials, to determine the effects of heat treatment or surface treatments on a material's hardness, and to assess the overall strength and durability of a material. They are also used in quality control and production processes to ensure the consistency and reliability of a material's hardness properties.

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