Comparative corrosion behavior of three titanium alloy base materials and their welds in a simulated chimney environment

This study investigates the corrosion behavior of titanium alloys (TA2, TC4, TB6) in a 3 % sulfuric acid flue gas environment using electrochemical tests and microscopic analyses (SEM/EDS, XRD, metallographic microscopy). Results show that TA2 base metal has lower corrosion resistance compared to its weld metal, while TC4 and TB6 exhibit opposite trends. Specifically, TC4 and TB6 base metals have lower corrosion current densities (0.9 and 0.5 μA/cm²) and higher corrosion potentials then their weld metals (1.93 and 2 μA/cm²). In contrast, TA2 base metal showed higher corrosion current density (2 μA/cm²) than its weld metal (0.35 μA/cm²) and HAZ metal (0.16 μA/cm²). Microscopic analyses reveal β phase transitions in TC4 and TB6 weld areas, leading to larger grain sizes and reduced corrosion resistance. Conversely, TA2 retains finer grains post-welding, enhancing its corrosion resistance. These insights clarify weld corrosion effects and provide valuable guidance for industrial applications of titanium alloys, particularly in designing and maintaining titanium alloy chimneys.