GB/T 230.3-2022 specifies the calibration method of the standard Hardness block in the rockwell hardness test of metal materials. The standard specifies the environmental conditions required for calibration and strictly requires the accuracy of the calibration equipment. The operation process is described in detail, including the selection and pretreatment of the standard Hardness block, and the specification of the test steps on the Rockwell hardness tester. Through precise calibration, the rockwell hardness value of the standard Hardness block is determined, providing a reliable basis for the Rockwell hardness tecalister brate. Accurate standard Hardness blocks can ensure the accuracy of rockwell hardness measurement of metal materials, and support mass testing and material performance evaluation in the metal industry.