Effect of Titanium Content on Hydrogen Induced Cracking of High Strength Low Alloy Welds in the H2S Containing Environment

Abstract:

In this paper, the microstructure and hydrogen induced cracking of SAW welds in API-X70 grade with different amount of titanium were studied. The investigation was carried out on the base metal, heat affected zone and weld metal with three different titanium amounts. The results showed that the centerline segregation region of the base metal was sensitive to hydrogen induced cracking while the heat affected zone did not show any kind of this failure.  Furthermore, we observed that with addition of titanium, the formation of acicular ferrite in the microstructure and hardness values were increased and stress oriented hydrogen induced cracks appeared in the weld metal. The optimum combination of the microstructure and hydrogen induced cracking resistance was observed in the weld metal containing 0.08% titanium.

Keywords: Microstructure, Hydrogen Induced Cracking, Titanium, Acicular ferrite