GB/T 23900-2009 Active

This standard specifies the method of measuring the ultrasonic velocity in materials using Type A pulse reflection ultrasonic flaw detection equipment.
This standard describes a method of measuring the ultrasonic velocity in the material being tested by comparing it with the ultrasonic velocity of a reference material (test block) whose ultrasonic velocity is known.
This standard is applicable to solid materials with a thickness of 5 mm or more, and the parallelism between the two surfaces perpendicular to the direction of ultrasonic energy propagation should be within ±3°, and the surface roughness of the surface coupled with the ultrasonic probe should be better than 3.2μm.
More accurate results can be obtained using other specially developed ultrasonic instruments, auxiliary equipment, and specialized techniques. Appendix A lists several other methods of measuring ultrasonic wave velocity.