Webster Hardness conversion to Brinell HBW

[kingnero]

I contacted

https://www.websterinstrument.com/

to see if they have any conversion tables or charts to HBW, but they replied that they only use the Rockwell scales.
I searched, but google wasn't of any help.
Before I spend a lot of money to try and make something myself (by the hand of a laboratory), does anyone know if there are other sources,
or in the worst case, what could I expect of accuracy of a conversion to HBW but first to Rockwell (using their charts or the conversion tables in EN ISO 18265) and then Rockwell to HBW (using EN ISO 18265)? I suspect not very much? A guess of a guess?

 

[EdStainless]

How about the ones in ASTM?
It depends on the material being tested.

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P.E. Metallurgy, consulting work welcomed

 

[kingnero]

ASTM E140 does not include Webster, as far as I know. Are there any others that might be of interest here?
We're talking extruded aluminium (range 30 -110 HBW).

I know what you mean, but at this moment I'll take what I can get. The alternative is going to cost quite some money, and right now it's for informative purposes only. Once we have some experience with the Webster instruments, we can go further.

 

[EdStainless]

Do it yourself.
I have had to do this many times over the years.

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P.E. Metallurgy, consulting work welcomed

 

[kingnero]

That's what I was afraid of...

 

[MagBen]

confused! what do you mean by "cannot find any conversion table"? this kind of table is everywhere! HBW is simply a Brinell testing using a WC indenter (vs originally using steel ball), you can convert Brinell to other scales, Rockwell, superficial, microhardness etc.
what is the issue?

 

[kingnero]

I got measurements reported in Webster (see link in first post), and normative values/tolerances in HBW.
We'd like a quick check to see where the (Webster) hardness situates in the HBW scale. In Europe, Webster is rather uncommon, so conversion tables including Webster are hard to find.

I'd very much appreciate (a link to) such a table if you know of any... I don't share your "everywhere" idea!

 

[MagBen]

Is Webster tester special?!
As long as you use a carbide indenter to test Brinell scale, cannot you treat it as a regular HB value? only difference is the load, e.g. 500kg, 3,000kg. Actually at lower hardness range, both steel and WC indenters yield a very similar result.
Here is an example link to conversion: file:///C:/Users/ben.zeng/Downloads/Hardness%20Conversion%20Poster.pdf
Or, click a link in the link:

https://www.struers.com/en/Knowledge/Hardness-testing/Brinell#

 

[kingnero]

I know what Hardness is, I don't know how to measure it.
Webster appears to be a proprietary method to measure hardness, so I wouldn't dare to guess whether or not it aligns with the Brinell scale.

I have all kind of conversion tables to my disposal, EN ISO 18625 (taking into account the base materials) being the most elaborate and reliable. This standard does not mention Webster. The Struers table also does not mention Webster. Actually, I haven't found much info about Webster hardness anywhere, which is why I asked the question here.

If I can use the Webster readings and interpret them as if they were HB(W) in the lower range, that information would be valuable to me.

I appreaciate the information so far!

 

[Steven_D_P]

I think you can convert from Webster to Rockwell to Brinell with the same error as converting directly to Brinell if the conversion tables are accurate.
This is easy to demonstrate.

Conversion table:
A | B | C
1 | 2 | 3
2 | 3 | 4
etc.

Let's say you have hardness in scale A and want it in scale C. Hardness in scale A is 1. If you look up hardness in scale C it would be 3. If you first converted to hardness to scale B you'd get 2, which converted to scale C also gives 3.

There might be a small increase in error when using 2 conversions because of rounding and you might have to interpolate which is also less accurate, but nothing that will substantially change the result.

What will matter is if they have conversion tables for correct material class or if they just have general conversion tables.

 

[Dhurjati Sen]

These Websters seem to be dynamic hardness testing equipment where the hardness is measured on rebound?

Surely they provide testing strips for calibration?

Check the hardness of these strips using a Brinell tester, then make your own conversion table.

This should not be very expensive.

DHURJATI SEN
Kolkata, India

 

[kingnero]

Thanks for all of your insights! I know what to do.

 

[Steven_D_P]

@Dhurjati Sen
If you want to convert accurately you'd need testing strips of the same material class.

 

[MintJulep]

Offered without endorsement.

https://www.razi-center.net/assets/Other/En/Metals hardness conversion.pdf

 

[SwinnyGG]

The 20 graduations on the WEBSTER® dial indicator cover the range between 20 and 100 on the Rockwell B Scale.

Seems like a pretty easy calculation to me to at least get close.

Would need to verify exactly what model tester was used.. it appears there are several with different ranges.

 

[kingnero]

They even provide tables, no need for calculations:

Too bad this isn't whatI'm looking for...

 

[SwinnyGG]

You have Rockwell, you can then get to Brinell. Apologies, but I guess I'm confused on why this is such a big deal.