Metals and their Special Testing Problems

Abstract

The differences in acoustic velocity of different types of steel, whether unalloyed or alloyed, are less than 5%, as shown in the following Table 29.1. For less exacting measurements, they can be neglected, where this concerns distance determination. However, the change in transverse velocity, which is usually in the same sense and of the same order, has a not inconsiderable influence on the beaming angle when beaming obliquely: at 70° a change of 1% already amounts to about 1.5°. For flaw locating it is therefore advisable to use the same steel as that of the specimen when calibrating the instrument [805].