Mechanical and Corrosion Properties of Welded Joints in New Generation Ferritic and Duplex Stainless Steels

Abstract

This study covers the very preliminary results of welding and characterisation of one novel duplex and two ferritic stainless steel grades. The so-called ”lean duplex” grade EN 1.4162 (UNS S32101) has 21.5% Cr-5% Mn-1.5% Ni-N, the ferritic EN 1.4509 (UNS S43940, AISI 441) 17% Cr, and the other, improved 21% Cr ferritic grade that fulfills also UNS S44330 standard requirements, but has no standard EN designation yet. Both ferritic stainless steels have low (< 0.02%) carbon content and double (Nb+Ti) stabilisation. The materials were used as 1.5 and 2 mm sheets, hence laser and resistance spot welding were selected for welding experiments. The joints were subjected to mechanical testing and critical pitting temperature (CPT) corrosion tests, which were performed on both the base materials and welds. The mechanical tests of the welds did not reveal any significant softening effect due to welding operations. Comprehensive CPT data were achieved for base materials and their welds using two different polarisation potentials, and the new 21% Cr ferritic grade shows a great promise in both as-received and welded conditions. This paper was written as part of the Finnish Metals and Engineering Competence Cluster (FIMECC)’s Demanding Applications (DEMAPP) program.