The Rockwell B Scale is used for comparing soft steels and nonferrous metals. A 1/16 diameter hardened steel ball is forced into a test specimen with a 40 kg minor load and then a 100 kg major load is applied. The major load is removed and the Rb number value is given by a dial or digital readout. The chart shown here gives a scale range of Rb values and compares it to Rockwell C (Rc) values.
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