Performance Evaluation of Austenitic Stainless Steel Weld by Ultrasonic Phased Array Inspection Based on Probability of
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COUSTIC METHODS
Performance Evaluation of Austenitic Stainless Steel Weld by Ultrasonic Phased Array Inspection Based on Probability of Detection Qiang Wanga, *, Kai Zhua, Linlin Wua, Haihang Lia, Xiaomeng Xua, and Sifan Gonga a
College of Quality and Safety Engineering, China Jiliang University, Hangzhou, Zhejiang, 310018 China *e-mail: [email protected] Received March 30, 2019; revised December 14, 2019; accepted April 29, 2020
Abstract—To evaluation capability of ultrasonic phased array (PHA) in industrial austenitic stainless steel (ASS) weld quantitatively, the 304 ASS butted weld specimen with various depth and side-drilled holes (SDH) was drilled to analyze reliability of PHA testing. Based on phased array probes, the ultrasonic waveform data are processed by in traditional dynamic depth focusing and total focusing method (TFM). The welding zone defects imaging results are compared. The probability of detection (POD) curves of ultrasonic response data were used for estimation the detection capability and reliability of ultrasonic PHA. Keywords: ultrasonic phased array, austenitic stainless steel, weld, microstructure, probability of detection DOI: 10.1134/S1061830920070086
1. INTRODUCTION Due to the excellent ductility and relatively low yield strength of austenitic stainless steel (ASS), strain strengthening technology is used for pressure equipments in nuclear power plant, such as auxiliary circuits of nuclear power plant are austenitic stainless steel. The non-destructive testing (NDT) techniques must allow the detection of the potential defects in the stainless steel pipes and welding [1, 2]. Though the ultrasonic examination was often used to inspect overlaying weld defects of large-scale steel structure made of alloy Cr5 cast steel or carbon steel [3], while the ASS welding zone is a difficult component to test using ultrasonic test, due to anisotropic nature of the welding zone and columnar grain size [4]. Attenuation of high frequency ultrasound, backscattering noise and beam redirection in ASS weld materials cause difficulties in the ultrasonic testing. Inspection of coarse-grained welding zone using ultrasonic phased array (PHA) has a relatively low probability of detection of cracks, because the crystalline structure of welds causes distortion and splitting of the ultrasonic beams which propagates anisotropic medium [5]. The manufacturing flaws, such as voids, un-fusions and cracks exist in ASS welded joints. Inspection of austenitic welds was carried out mainly on radiographic techniques [6]. The developed ultrasonic phased array system and flaw classification concept are expected to enhance the efficiency and reliability of the NDT of nuclear power plant components [7]. The focusing effect of the PHA can improve the signal-to-noise ratio (SNR) in coarse grained material. The combination of mechanical scanning and electronic beam steering increases the flaw detect-ability. Concerning the flaw detection in highly scattering environment, it also was used to actual polycrystalline weld materia
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