Multiscale characterization of seawater pipe erosion of B10 copper\u2013nickel alloy welded joints

Dalei Zhang,Xiaohui Dou,Liuyang Yang,Yingshuang Liu,Ran Liu,Shaohua Xing,Enze Wei

doi:10.1038/s41598-022-06033-w

Abstract

In seawater pipeline, the welding joint is a non-uniform structure composed of welding seam, base metal and heat affected zone. It has inhomogeneity in chemical composition, organizational structure, residual stress, etc. As local defects and high turbulence accelerate corrosion, the welding joint is often the weakest link in pipeline corrosion. Herein, the electrochemical corrosion behavior of B10 alloy welded joint in flowing seawater is studied from macroscopic and submicroscopic viewpoints using AC impedance, linear polarization, array electrode and morphological characterization. The results reveal that the corrosion rate of weld metal (WM), base metal (BM) and heat-affected zone (HAZ) decreased with the increase of time. Combined with SEM and EDS analysis, it can be seen that the increase in time led to the decomposition and accumulation of corrosion products, which gradually enhanced the corrosion resistance of welded joints. At the submicroscopic scale, WM acts as a cathode to mitigate corrosion during the later stages of high flow rate.

Highlights

In seawater pipeline, the welding joint is a non-uniform structure composed of welding seam, base metal and heat affected zone
In (b), R1 represents the solution resistance, CPE1 represents the capacitance of surface film, R2 represents the resistance of surface film, CPE2 refers to the electrical double layer capacitance of the electrode/solution interface, and R3 denotes the charge transfer resistance of the sample
The effect of different flow rates on the electrochemical corrosion of B10 copper-nickel alloy welded joint under flowing seawater has been studied in detail

Summary

Introduction

The welding joint is a non-uniform structure composed of welding seam, base metal and heat affected zone. At the same flow rate, the total impedance value of the three zones of welded joint followed the given trend: WM > BM > HAZ.

Results

Conclusion