Rockwell Hardness Testing of Tin Mill Products

Tin mill products of Rockwell superficial hardness tests use the 15T and 30T scales. Tests shall be made in accordance with the methods outlined in Test Methods E 18 and Test Methods and DefinitionsA370 with the exceptions given in the following sections.

All tests shall be made using the diamond spot anvil and a 1.588 mm hardened steel ball indenter.

The Rockwell superficial scale to be used shall be determined from the nominal thickness of the material as given in the following table:

Nominal Sheet Thickness	Rockwell Superficial	Major Load
mm	Scale	kgf
0.212 and less	15T	15
0.547–0.213	30T	30

Hardness tests made on the 15T scale may be converted to the 30T scale by the use of the following Table. It is recognized that such conversions are for convenience in reporting and that conversion, particularly from tests on thin and soft materials, is not an accurate process

Conversion Table (Approximation) Rockwell Hardness Testing

HR30T	HR15T	HR30T	HR15T	HR30T	HR15T	HR30T	HR15T
82.0	93.0	65.0	84.0	74.0	88.5	55.0	79.5
81.5	92.5	64.0	...	73.5	...	54.5	...
81.0	...	63.5	83.5	73.0	88.0	54.0	79.0
80.5	92.0	62.5	83.0	72.0	87.5	53.0	78.5
80.0	...	62.0	...	71.5	...	52.5	...
79.0	91.5	61.5	82.5	71.0	87.0	51.5	78.0
78.5	...	60.5	82.0	70.0	86.5	51.0	77.5
78.0	91.0	60.0	...	69.5	...	50.5	...
77.5	90.5	59.5	81.5	69.0	86.0	49.5	77.0
77.0	...	58.5	81.0	68.0	85.5	49.0	76.5
76.0	90.0	58.0	...	67.5	...	48.5	...
75.5	89.5	57.0	80.5	67.0	85.0	47.5	76.0
75.0	...	56.5	...	66.0	...	47.0	75.5
74.5	89.0	56.0	80.0	65.5	84.5	46.0	...