GB/T 4340.3-2012 specifies the calibration specification for standard Hardness blocks in Vickers Hardness testing of metal materials. It clearly states that the calibration needs to be carried out in a specific environment, specifies the operation steps in detail, and requires strict accuracy of the calibration equipment. Through a rigorous process, the Vickers Hardness value of the standard Hardness block is accurately determined to ensure that its Hardness value is accurate and traceable. Accurately calibrated Hardness blocks are the benchmark for calibrated Vickers hardness testers, providing a reliable basis for Vickers hardness testing of metal materials and assisting the mass inspection and performance evaluation of products in the metal industry.