Combined acoustic emission and electrochemical methods for analyzing the uniform corrosion behavior of X90 high-grade steel pipelines

Long-distance, large-diameter, and high-pressure pipelines represent the future of oil and gas pipeline construction. X90 pipeline steel is expected to become the standard steel due to its high transmission efficiency and lower cost in the future, yet corrosion poses the most significant challenge to the development of high-strength pipelines. This study focuses on monitoring the uniform corrosion process of X90 steels using acoustic emission (AE) and electrochemical testing systems. The AE signals from corrosion were processed using wavelet de-noising, decomposition, and reconstruction to extract signal characteristics. Experimental results reveal that the corrosion process of X90 steel can be categorized into three stages: initial metal dissolution, corrosion product accumulation, and corrosion stabilization. Signal activity and strength follow normal distributions throughout these stages. During metal dissolution and corrosion stabilization, AE signals exhibit a frequency range of 100–200 kHz with relatively low amplitude. Conversely, during corrosion product accumulation, signals display a narrow frequency range with higher amplitudes, typically around 3 × 10 -4 V. Moreover, the appearance of a double-peak signal suggests the presence of two distinct AE sources.