Global voestalpine Böhler Welding specialists for cladding, petrochemical and chemical processing, M Decherf, R Demuzere and F Ciccomascolo, present an advanced electroslag strip cladding process that enables thin single layer Alloy 625 deposits to be achieved that meet the iron (Fe) content requirements for the oil & gas and chemical processing industries.
One of the most interesting features of the electroslag strip cladding process (ESSC) is that it can achieve the desired chemical composition in only one layer for almost all alloys used in the process industry. Among them, Alloy 625 is of course widely used in the oil & gas and chemical processing industry.
For this alloy, new thin single layer solutions have been developed with the aim of reducing the overlay thickness in order to save material and improve productivity, while meeting the deposited metal industry requirements, which are very demanding in many cases.
Controlling the dilution from the parent material and balancing the chemistry by means of new flux features, it has been possible to achieve high quality results with single layers thinner than 4.0 mm, with the iron content below 10% as per the requirement. An iron content requirement below 7% can also be met in a single layer, while two layers are necessary with conventional solutions available in the market.
This article gives an overview of the relevant specifications, followed by details on the applied welding conditions and the quantitative results achieved, which show the benefits in terms of material saving and productivity increases compared with conventional strip cladding. Chemical composition and mechanical properties obtained with the newly developed solutions are also presented. Finally, results achieved in relevant corrosion tests are discussed.