Spatially resolved ultrasonic attenuation in resistance spot welds: Implications for nondestructive testing

• Published in: Ultrasonics Vol. 48; no. 5; pp. 343 - 350
• Main Authors: Mozurkewich, George, Ghaffari, Bita, Potter, Timothy J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-09-2008; Elsevier Science
• Subjects: 43.35.Cg; 81.20.Vj; 81.70.Cv; Algorithms; Attenuation; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Grain scattering; Image Interpretation, Computer-Assisted - methods; Materials science; Materials testing; Materials Testing - methods; Metals - chemistry; Nondestructive evaluation; Physics; Resistance spot weld; Ultrasonics; Ultrasonography - methods; Welding - methods; 43.35.Cg; Nondestructive evaluation; Grain scattering; 81.20.Vj; Resistance spot weld; Attenuation; 81.70.Cv; Ultrasonics; Grain size; Frequency dependence; Propagation velocity; Phase transformations; Nondestructive testing; Ultrasonics; Attenuation; Resistance spot weld; Grain scattering; Nondestructive evaluation; Ultrasonic waves; Wave damping; Sound velocity; Spot weld; Welded joints; 43.35.Cg; 81.70.Cv; 81.20.Vj; Rings; Spot welding; Ultrasonic testing; Metering
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/j.ultras.2008.01.004

Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology.