This standard is applicable to the production and quality control of carbon steel and alloy steel test blocks for the inspection of these materials, but it is also applicable to the preparation of test blocks for other types of materials, such as nickel based alloys, titanium alloys, aluminum alloys, etc. The steel comparison test block is suitable for both direct contact and water immersion pulse reflection ultrasonic testing methods. The sound attenuation of the material used for making the comparison test block should be suitable for the tested material. Note: Unless otherwise specified, select the test blocks produced from the table below. The conventional test block classification is as follows: compare the size of the test blocks and the recommended test block group