Evaluation of Corrosion Performance of Titanium/Steel Joint Brazed by Cu-Based Filler Metal

Furnace vacuum brazing has been employed to join commercially pure titanium and low carbon steel using copper-based filler metal with the composition of Cu-10.6Mn-1.9Ni, at.%. Three different brazing temperatures 930, 970, and 1000 A degrees C and a holding time of 15 min were studied and evaluated. The corrosion behavior of the joint in 0.1 M sulfuric acid was investigated using immersion and electrochemical tests. Measurements of corrosion potential, corrosion current density, corrosion rate, polarization resistance, weight loss, and morphology of corrosion attack were used in this study. Experimental results showed that severe corrosion attack of the steel side at the interfacial area is clearly observed. Despite the difference in corrosion rate values obtained by electrochemical and weight loss measurements, the trend of results was identical to a large extent. Corrosion resistance of the joint showed a general tendency to increase with rising brazing temperature. The lowest corrosion rate was obtained for the couple bonded at 1000 A degrees C. Meanwhile, at the lowest joining temperature of 930 A degrees C, corrosion rate showed a higher value. The results of joints corrosion resistance were attributed to the difference in microstructure features and chemical analysis.