INTRODUCTION & BASIC PRINCIPLE
Ultrasonics is the name given to the study and application of sound waves having frequencies higher than those which the human ear can hear. Adults with normal hearing can hear frequencies up to a range of 16,000 cycles per second (16 kHz) to 20,000 cycles per second (20 kHz). Ultrasonic nondestructive testing is the use of ultrasonics to examine, or test, material without destroying the material.
APPLICATIONS
An ultrasonic test may be used to measure the thickness of a material or to examine the internal structure of a material for possible discontinuities such as voids and/or cracks. Because of the basic characteristics of ultrasonic testing, it is used to test a variety of both metallic and nonmetallic products such as welds, forgings, castings, sheet, tubing, plastics, and ceramics etc. since ultrasonic testing is capable of economically revealing subsurface discontinuities (variations in material composition) in a variety of dissimilar materials, it is one of the most effective tools available to quality assurance personnel.