Hardness Testing 1

[FeQC]

I'm looking for conversion formula for Brinell 3000kgf Standard to Rockwell C. I want to build my EXCEL spreadsheets with formula in it, as I can only test for Brinell but reports must be submitted in Rockwell and I want to skip the conversion calculator step. If it makes a difference all testing will be on mild steel.

 

[redpicker]

Check out ASTM E140.

I am curious, though, about what Rockwell 'C' values you expect to get on mild steel samples. The 'C' scale is only valid down to 20 HRC or so, and I'd expect mild steel to be quite a bit below that hardness level.

rp

 

[metengr]

You should keep the hardness reported in Brinell. It provides the widest range of hardness and is typically for universal in reporting.

 

[mrfailure]

From ASTM E140 Appendix X1:

HRC = 1.81673E+01 + 1.20388E-01(HBW) - 6.94388E-05(HBW)^2 - 4.88327E+03(HBW)^-1 R^2=0.9998

Appendix X2:

HRB = 1.14665E+02 + 8.82795E-02(HBS) - 1.41855E-04(HBS)^2 - 6.6952E+03(HBS)^-1 R^2=0.9998

A couple of notes:

You should be using a tungsten ball, but it only is different from standard steel measurements above 46 HRC.

As always, conversions are to be considered estimates. These two conversions apply specifically to ferritic steel.

Finally, I note that I managed a mini-project a few years ago where we did the same task making a spreadsheet allowing E140 conversions between different nickel readings. Having done the exercise, these days I personally prefer to do this manually be interpolating from the E140 tables because the curves generated by the equations can deviate from table values, resulting in questioning from someone checking against the tables.

Aaron Tanzer

http://www.lehightesting.com

 

[FeQC]

Hardness testing is on thermal cut edges of main load carrying tension members per AASHTOO/AWS D1.5. Reported values are not to exceed 30 Rockwell C, and usally average around 15.

 

[mrfailure]

FeOC,

As others have indicated, you are on the Rockwell B scale range and should not interpret as Rockwell C or convert below the Rockwell C floor of 20 HRC. Being in the HRB range (which tops out at 100 HRB) automatically means you are not exceeding your specified maximum value.

Aaron Tanzer

http://www.lehightesting.com