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Brinell to Rockwell C Hardness conversion

Brinell to Rockwell C Hardness conversion

Brinell to Rockwell C Hardness conversion


Having a slight problem in getting a conversion of 305 BHN to Rockwell C, I have been through the many tables specified (i.e Zues book etc) and have managed to obtain a conversion from 301 BHN to 32 Rc, all tables seem to give between 301 and 311 BHN is there a recognised method to obtain 305?

Any help appreciated

Material is a Low alloy steel


RE: Brinell to Rockwell C Hardness conversion

Conversion between hardness scales is dependent upon the metal.  See ASTM E140.

RE: Brinell to Rockwell C Hardness conversion

As metalonis has noted ASTM E 140 will give you the approximate correlation for your material. You can interpolate between the 301 and 311 Brinell numbers to give you a value of say 32.5 Rockwell C for steel but remember that the initial tables are only approximate so be careful how you use the numbers.

RE: Brinell to Rockwell C Hardness conversion

There is no recognized method to convert any indentation hardness values for materials.  Charts have been created based on different tests on the same material and general correlations have been established.

SAE J417 HARDNESS TESTS AND HARDNESS NUMBER CONVERSIONS shows 303 HBW (10 mm tungsten carbide ball with 3000 kg force) is equal to 32.2 HRC.  It also shows 313 HBW is equal to 33.3 HRC.  You could assume a linear response between these two values and state that 305 HBW is approximately equal to 32.4 HRC.



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RE: Brinell to Rockwell C Hardness conversion

Sheers folks for the info, I had seen some of the answers and done a Linear response and calculated appox 32.3 HRC, was just trying to ensure that there was no definative rule, but you folks have settled my mind cheers


RE: Brinell to Rockwell C Hardness conversion

The Uconeer unit conversion software developed by Katmar(a great member of eng-tips) can be downloaded from www.katmarsoftware.com

This includes hardness unit conversion and the value is matching with the above specified value.


RE: Brinell to Rockwell C Hardness conversion


Cheers for the info, downloaded the convertor top notch, better than the Dinosaur program i am curently using. again cheers


RE: Brinell to Rockwell C Hardness conversion

For hardness conversions we have devloped out own.  Using our materials, shapes, hardnesses, surface finishes, and all.
We tested on every machine in house in every range/scale used.  We also have a couple of local labs test as well.
These coversions are at least 10 HB different than you would get from standard tables (even using the correct alloy ones).
If this is important to you, you should have some testing done.
You should also remember to run a gage study on your hardness testers.  You might be surprized at how much variation there is in readings.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

RE: Brinell to Rockwell C Hardness conversion

There is no point in looking for an univocal value of hardness in one scale and method to correspond exactly to a value from a different method.
Hardness is better defined in ranges than in single values.
The same hardness reference block (homogeneous by definition) tested by different laboratories will give ranges of results, hopefully overlapping, not the kind of accuracy one can expect in the measuring of physical properties.
Furthermore each method is preferred for definite materials and conditions.
Brinell, covering a relatively extended area, provides some sort of surface hardness average.
Rockwell C is pointed to the tip of the diamond indenter and is suitable for more homogeneous structures.
Looking for decimal figures in Rockwell C would require equipment and procedures to be found only in national laboratories.


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