GB/T 21838.3-2022 standardizes the calibration of standard blocks for instrumented indentation tests of metal materials. It clearly calibrates environmental conditions, puts forward strict requirements for the accuracy of the instruments and equipment used, and details the selection, cleaning and calibration operation process of standard blocks. Through rigorous calibration, determine the accurate Hardness value and related parameters of the standard block, and provide a reliable reference for the calibrating of the instrumented indentation testing machine. Accurately calibrated standard blocks can ensure the accuracy and traceability of metal hardness of materials and material parameter measurement, and help metal material performance research and mass control.