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Rockwell Minimum Thickness- Reference Information and Standards -

Minmum thickness is one of the frequently overlooked aspects of hardness testing. As a rule

users need to maintain a sample thickness at least ten times the maximum depth of

indentation unless it is known that a material with a thinner thickness will provide the same

result. The chart below provides ASTM specifications as found in ASTM E18.

This mimum thickness is often overlooked since operators will get a "result" with when their

material is too thin to test accurately, but it will be affected by the test anvil hardness. There

are times when there is no choice and a non-standard result is better than no result. In this

case operators may use multiple layers of the same material to get a better thickness and a

non-ASTM E-18 result. For testing some thin soft sheet materials made of tin users have

standardized on using a diamond spot anvil and a steel ball -- the idea being that the diamond

spot anvil provides the most consistent "bad" result so the operators have a better feel for

performance of the material.

Thickness Rockwell Scale

Inch Metric HRC HRA HRB HRF 15N 30N 45N 15T 30T 45T

0.006 0.150 -- -- -- -- 92 -- -- 91 93 --

0.008 0.200 -- -- -- -- 90 -- -- 86 78 --

0.010 0.250 -- -- -- -- 88 -- -- 81 62 --

0.012 0.300 -- -- -- -- 83 82 77 75 44 71

0.014 0.360 -- -- -- -- 76 78.5 74 68 24 62

0.016 0.410 -- 86 -- -- 68 74 72 -- -- 53

0.018 0.460 -- 84 -- -- -- 66 68 -- -- 43

0.020 0.510 -- 82 -- -- -- 57 63 -- -- 31

0.022 0.560 69 78 -- -- -- 47 58 -- -- 18

0.024 0.610 67 76 94 98 -- -- 51 -- -- 4

0.026 0.660 65 71 87 91 -- -- 37 -- -- --

0.028 0.710 62 67 80 85 -- -- 20 -- -- --

0.030 0.760 57 60 71 77 -- -- -- -- -- --

0.032 0.810 52 -- 62 69 -- -- -- -- -- --

0.034 0.860 45 -- 52 -- -- -- -- -- -- --

0.036 0.910 37 -- 40 -- -- -- -- -- -- --

0.038 0.960 28 -- 28 -- -- -- -- -- -- --

0.040 1.020 20 -- -- -- -- -- -- -- -- --

Rockwell Hardness Chart (plus a PDF)

(aka Hardness Scale Conversion Chart)

Round Correction Factor

Hardness Minimum Thickness

ASTM Hardness Test Methods

Rockwell Hardness Scales

Brinell Hardness Chart (plus a PDF)

Rockwell Hardness Testing

Brinell Hardness Testing

Microhardness Testing

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Rockwell Minimum Thickness Specifications for Hardness Testing http://www.qs-hardnesstester.com/hardness-minimum-thickness.html

1 of 2 2/26/2015 12:56 PM

Rockwell Minimum Thickness Specifications for Hardness Testing http://www.qs-hardnesstester.com/hardness-minimum-thickness.html

2 of 2 2/26/2015 12:56 PM