Per: lucas alves de moraes (UFC), lívia carlos cidrão (UFC), josé adroaldo silva de moura filho (UFC), giovani dalpiaz (petrobras/cenpes), Ricardo Reppold Marinho (petrobras/cenpes), marcelo torres piza paes (petrobras/cenpes), émerson mendonça miná (UFC), marcelo ferreira motta (UFC), helio cordeiro de miranda (ufc), cleiton carvalho silva (ufc)
Abstract:
This work evaluated the discontinuous High-Dilution Zone (HDZ) found at the dissimilar interface of ASTM A182 F22/Inconel 625 joints welded by the Plasma Transferred Arc (PTA) process. This joint configuration is widely applied in manifold HUB connections for water injection or crude oil subsea transport systems. Investigations utilising optical microscopy and SEM with EDS technique were conducted. Microhardness mappings and thermodynamical simulations were carried out. The results reveal a complex zone with microstructure that presents gray and white tonalities between HAZ and FZ, which are result of chemical composition gradient. Its formation is related to restricted liquid movement at the edge of weld pool during welding, as well as differences in physical-chemical properties of the two alloys. High-hardness martensite formation in the discontinuous HDZ represents a risk for hydrogen-assisted cracking of these dissimilar joints.