Corrosion behaviour of dissimilar TIG welded austenitic stainless steel AISI 304 and martensitic stainless steel AISI 420

Welded joints of dissimilar metals are often required in nuclear and chemical industries. Among the various types of material combinations, welded joint of austenitic stainless steel and martensitic stainless steel is one good option. Due to differences in mechanical, metallurgical and corrosion properties between the two dissimilar materials, selections of suitable welding parameters, filler materials, shielding gas mixture etc. are extremely important in order to avoid drastic thermal gradient, hence significant welding distortions. In the present work, defect free TIG welding of dissimilar materials AISI 304 and AISI 420 has been made successfully. Quality of the welded joint has been judged through tensile test, microstructural investigation, micro-hardness measurement, SEM fractography and XRD analysis. Corrosion behaviour of the welded joint at different concentrations of NaCl has been measured through potentio-dynamic polarization. Weldment shows passivity at different solutions.