Weldability of a Supermartensitic Stainless Steel 12Cr4Ni1Mo Pipeline and the Effect of Welding Current on Precipitated Ferrite δ in the HAZ

The weldability of the recently introduced supermartensitic stainless steel (SMSS) 12.5Cr4Ni1Mo is investigated by observing the emerging phases resulting from the weld in the heat affected zone and the melted zone as well. We noticed a practically similar martensitic structure to be dominant in the melted zone of TIG autogenous welds after normal cooling conditions. Some ferrite delta phase was observed to precipitate in the heat affected zone. This emerging ferrite delta phase was observed to precipitate according to a specific pattern localized in the heat affected zone. This pattern was found to be closely related to the welding parameters, especially the welding current. We attempted to establish experimentally a correlation between the welding current and the percentage of precipitated ferrite delta phase in the heat affected zone. The study presents as well an experimental evaluation of some mechanical properties of TIG autogenous welds on (SMSS) stainless steel 12.5Cr4Ni1Mo simulating the use of matching welding consumable. The obtained results, so far, lead to an interesting convenience of investigating the use of matching welding consumable with such steel.