For any given thickness, the indicated Rockwell hardness is the minimum value acceptable for testing.

For a given hardness, material of any greater thickness than that corresponding to that hardness can be tested on the indicated scale.

Note A: These approximate hardness numbers are for use in selecting a suitable scale and should not be used as hardness conversions.

If necessary to convert test readings to another scale, refer to Hardness Conversion Tables E 140 (Relationship Between Brinell Hardness, Vickers Hardness, Rockwell Hardness, Rockwell Superficial Hardness, and Knoop Hardness).