Abstract
Cladded materials are used by the oil and gas industry due its advantages in combining the good mechanical properties
and low cost of the steel with the excellent corrosion resistance of the Inconel 625. This combination of materials are specially used
on rigid risers, where aggressive environment such as organic acids, carbon dioxide and H2S are present inside the pipeline.
Conventional arc welding processes can bring several issues, such as long welding time, melting of involved materials, Fe dilution
inside weld metal (generally Inconel 625) and brittle phase precipitation. It is known that FSW joints presents better mechanical
properties and lower tensile residual stresses when compared with conventional arc welding process, as well as having greater
reproducibility and control of process parameters. Thus, a two-step Friction Stir Welding (FSW) process on 7mm cladded API X65 steel plates was studied. The first step of the process consisted in welding the 4mm X65 steel layer while the second step joined
the 3mm Inconel 625 layer. Detailed mechanical and microstructural analysis were performed. Correlation with the underlying
physical mechanics will be discussed.
