Effect of Weld Geometry and Material Type on PAUT Acoustic Signatures of Crack and Porosity Defects

The accurate characterization of weld defects using Phased Array Ultrasonic Testing (PAUT) is essential for ensuring structural integrity, yet the acoustic signatures of planar cracks and volumetric porosity are influenced by material properties and joint geometry. This study extends prior research on PAUT defect classification which established a multi-feature classification matrix achieving 100% accuracy on 9.50 mm thick steel V-groove butt welds by systematically investigating how variations in weld geometry and material type affect the distinguishing acoustic signatures of cracks and porosity. Experimental PAUT inspections were conducted on specimens with varying weld geometries (Single-V, double-bevel, narrow-gap, and T-joint configurations) and material types (mild steel, austenitic stainless steel, and dissimilar metal welds). Data analysis compared A-scan, S-scan, and C-scan responses, evaluating the robustness of classification matrix parameters when material and geometric variables change. The findings demonstrate that while fundamental distinguishing features remain valid, their interpretation requires material-specific and geometry-specific calibration, with optimized inspection parameters critical for maintaining classification reliability. Classification accuracy ranged from 100% for mild steel V-groove welds to 80–87% for dissimilar metal welds in complex geometries. This study provides practical guidance for adapting the classification matrix to diverse inspection scenarios, enhancing PAUT reliability across the full range of industrial welding applications.

Phased Array Ultrasonic Testing (PAUT), Weld Geometry Effects, Material Effects, Defect Characterization, Classification Matrix

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