Rockwell hardness testing apply three test force, three indenters, and the total nine assembly matches nice scales and the nine scales almost includes all metallic materials.
The most common use scales are HRC, HRB and HRF, HRC used in the materials like quenched steel, temperature steel, hardened and tempered steel and part of stainless steel, this is widely used in metal working industry. HRB used in the materials as annealed steel, normalized steel, mild steel, part of stainless steel and hard copper alloy. HRF used in the materials as pure copper, soft cooper alloy and hard aluminium alloy. HRA used in most of ferrous metal, but usually test the Kentanium and thin hard steel.
Rockwell superficial hardness testing uses three testing force, two indenters and there are six matches scales.
Rockwell superficial hardness testing is the supplementary of Rockwell hardness testing, when the testing is thin and work piece is small, then we should use the Rockwell superficial hardness testing. It also use the same indenter with Rockwell hardness testing, but the testing force is much lower. N scales of Rockwell superficial hardness testing is similar with Rockwell HRC, HRA and HRD, T scales of Rockwell superficial hardness testing is similar with Rockwell HRB, HRF and HRG.
