Microstructure and corrosion properties of single layer Inconel 625 weld cladding obtained by the electroslag welding process

Abstract

This work investigates the microstructure and corrosion characteristics of an Inconel 625 weld cladding deposited by the electroslag welding (ESW) process with a single layer on an ASTM A516 Gr. 70 steel plate with a heat input of 11.7 kJ/mm. Microhardness testing, metallographic examination and corrosion tests were performed on samples removed at 1 and 3 mm parallel to the fusion line. Metallographic characterization was performed by optical and scanning electron microscopy. Energy dispersive spectrometry was also used to evaluate the composition of the secondary phases. Cyclic polarization tests in 3.5% NaCl solution were performed at the same position as the metallographic examinations. Immersion corrosion tests following the ASTM G 48 Method A were also conducted. Equivalent corrosion results were obtained at both positions due to the austenitic microstructure of the weld metal containing a very low amount of secondary phases. The results of the corrosion tests were consistent with the microstructure and low dilution and remained at a level acceptable for structures. Thus, the ESW process may be considered an alternative for overlay welding with Inconel 625 with reduced thicknesses, because good results were observed at only 1.0 mm from the fusion line, and this could represent a significant cost reduction.

Keywords

• Alloy 625
• Electroslag process
• Metallographic examination
• Corrosion tests
• Cladding