Rationale

Section A1.3.4.2 states that the average measurement shall indicate a hardness of 130 ± 1.0 Rockwell units when Rockwell ball scales B, E, F, G, H and K are used, or within 100 ± 1.0 Rockwell units when any other Rockwell scale is used. When performing hysteresis on machines using the ¼” and ½” ball diameters (scales L, M, P, R, S and V) these scales use the same calculation as the 1/16” and 1/8” ball indenters, so the machine hysteresis should be the same for these scales. The only possibility that a value >100 can be achieved is if 130 is used as the basis in the formula. Based on this information, I think that E18 must be changed to reflect the proper hysteresis value of 130 ± 1.0 Rockwell units for the ¼” and ½” ball diameter indenters (scales L, M, P, R, S and V).