Location

Seattle, WA

Start Date

1-1-1996 12:00 AM

Description

Ultrasonic testing is used for the detection of flaws in critical parts, such as forgings in gas turbines[3]. Benign features within the microstructure, such as grain boundaries, also reflect part of the ultrasonic pulse. These signals will generally be of a lower amplitude than flaw signals, since they represent a softer discontinuity in material properties. Figure 1 shows a simplified distribution of such ‘grain noise’ signals, and a possible distribution of signals resulting from small flaws. Two difficulties arise due to the presence of grain noise: (1) The smallest flaw signals cannot be observed since they are masked by the grain noise. This defines the limiting resolution of the scan. (2) The largest noise signals are mistaken for flaws, leading to ‘false calls’ and the rejection of sound material.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

15B

Chapter

Chapter 6: Material Properties

Section

Ultrasonic Backscatter and Attenuation

Pages

1479-1485

DOI

10.1007/978-1-4613-0383-1_193

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

An Experimental Investigation of Ultrasonic “Grain Noise” in Titanium -6AL-4V

Seattle, WA

Ultrasonic testing is used for the detection of flaws in critical parts, such as forgings in gas turbines[3]. Benign features within the microstructure, such as grain boundaries, also reflect part of the ultrasonic pulse. These signals will generally be of a lower amplitude than flaw signals, since they represent a softer discontinuity in material properties. Figure 1 shows a simplified distribution of such ‘grain noise’ signals, and a possible distribution of signals resulting from small flaws. Two difficulties arise due to the presence of grain noise: (1) The smallest flaw signals cannot be observed since they are masked by the grain noise. This defines the limiting resolution of the scan. (2) The largest noise signals are mistaken for flaws, leading to ‘false calls’ and the rejection of sound material.