The Rockwell C Scale is primarily used for comparing thick, hardened metals, harder than Rb100. A conical diamond (Brale) is forced into a test specimen with a 40kg minor load and then a 150kg major load is applied. The major load is removed and the Rc number value is given by a dial or digital readout. These charts shown here give a scale range of Rc values and compares it to Rockwell B (Rb) values.
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