GB/T 4340.2-2025 "Metallic Materials—Vickers Hardness Test—Part 2: Verification and Calibration of Testing Machines" applies to the verification and calibration of Vickers hardness testing machines and diagonal measurement systems, including portable hardness testers, but does not apply to hardness testers based on other principles such as ultrasonic impedance methods. The standard specifies two verification methods: direct verification and indirect verification. Direct verification covers the inspection of parameters such as test force, indenter, and measurement systems, with new requirements for test force deviation in small force ranges. Indirect verification involves the overall inspection of the machine using standard reference blocks, specifying the number of indentations, error limits, and repeatability requirements. The standard also regulates the verification cycle and report content, providing a technical basis for the correct use and maintenance of hardness testing machines.