Location

Seattle, WA

Start Date

1-1-1996 12:00 AM

Description

The ultrasonic inspection of large grained engineering materials such as titanium alloys is often limited in finding low reflectivity targets due to reflections from grain boundaries. These unwanted signals are often referred to as grain noise. Recently, experimental work was performed showing the effects of ultrasonic scan parameters on grain noise level and signal to noise ratio. [1,2] Techniques such as using broadband ultrasonic pulses, subsurface focused beams, higher frequencies and smaller beam diameters were shown to dramatically improve SNR for both air-backed and low reflectivity targets in Ti6–4. There is one common element in all these items which reduce the ultrasonic noise level when compared to that of the target signal: a reduced ultrasonic beam volume. This paper will outline an experimental technique for measuring the volume of an ultrasonic pulse and demonstrate with experimental data that the level of ultrasonic grain noise in titanium alloys is proportional to that volume.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

15B

Chapter

Chapter 6: Material Properties

Section

Ultrasonic Backscatter and Attenuation

Pages

1495-1502

DOI

10.1007/978-1-4613-0383-1_195

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Ultrasonic Noise and the Volume of the Ultrasonic Pulse

Seattle, WA

The ultrasonic inspection of large grained engineering materials such as titanium alloys is often limited in finding low reflectivity targets due to reflections from grain boundaries. These unwanted signals are often referred to as grain noise. Recently, experimental work was performed showing the effects of ultrasonic scan parameters on grain noise level and signal to noise ratio. [1,2] Techniques such as using broadband ultrasonic pulses, subsurface focused beams, higher frequencies and smaller beam diameters were shown to dramatically improve SNR for both air-backed and low reflectivity targets in Ti6–4. There is one common element in all these items which reduce the ultrasonic noise level when compared to that of the target signal: a reduced ultrasonic beam volume. This paper will outline an experimental technique for measuring the volume of an ultrasonic pulse and demonstrate with experimental data that the level of ultrasonic grain noise in titanium alloys is proportional to that volume.