Hardness Conversion: Vickers to Rockwell F

vmuro · Nov 17, 2010

Hi all,

I have been asked to determine a supplier for copper crush washers for fluid transfer applications. Our hardness requirement is in Vickers, 30-50 HV, and one potential supplier stated that they can meet a max of 65 on the Rockwell F scale. I can not find any conversion chart or table online to compare these values, and I was hoping someone here can point me in the right direction or verify for me if 65HRF is within the 30-50 HV range. Thanks in advanced.

-VM

blacksmith37 · Nov 17, 2010

ASTM E140 (1979 ed.) : VHN is about equal to RF in that range, 65F= 62 VHN, 50.5F= 50 VHN, the table4 that I have ends at 45 VHN (= 40 F).

TVP · Nov 18, 2010

VM,

The data that blacksmith37 provided is for a cartridge brass alloy (70%Cu, 30%Zn). Data for unalloyed copper is in a different table and has the following conversions:

HV HRF
50 41.5
48 39
46 36
44 33.5
42 30.5
40 28

vmuro · Nov 18, 2010

Thanks for your help. The specific material I am looking at is Copper C11000 (99.90% Cu - 0.03% OE) and the hardness is determined at the annealed condition. TVP, it looks like values, for unalloyed copper, are best for me to use.

Also, shouldn't the supplier be able to make the conversions themselves? Looking at the values, if my supplier can reach up to 65 HRF max, it's well within the 30-50 HV range, so they should know not to exceed 41.5 HRF.

EdStainless · Nov 19, 2010

You should never convert harness numbers. Those are only approximations. If you convert you should always give the original reading also so that the user know that it is a conversion.
We have done correlations our selves and found the published values to be off >5 points. It is so dependent on alloy, surface condition, and hardness levels that we now only report native units.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

blacksmith37 · Nov 19, 2010

I stand (or sit) corrected. The "copper" Table 7 is in my antique book , but I stopped as soon as I came to any copper base table (Table4 70:30 , cartridge, admiralty, etc).

vmuro · Nov 19, 2010

EdStainless,

Is it best to simply go with a supplier that can actually performs a Vickers test and meet the specified range as opposed to going with someone which would require hardness conversion?

I am fairly new and do not want to screw anything up. As you mentioned, >5 deviation can definitely cause in issue if converting.

tomwalz · Nov 19, 2010

A test shouldn't be a big deal for a supplier or for you.

The only real conversion method I trust is to do identical parts at the same time by different methods on good equipment.

Traditionally hardness equipment is under-maintained, especially the indenters.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

tomwalz · Nov 22, 2010

This is about the best set of coversion tables I have found.
Still I would add an app. to any converted hardness value. I think it is adequate for speehes, etc. to give an approximate idea but I do not think it would suffice in your application.

http://www.gordonengland.co.uk/hardness/hvconv.htm

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

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