Stress-corrosion cracking behavior of AISI-409 welded with a filler metal flux cored AWS E316LT1-4

Ferritic stainless steel is essential in many industries due to its corrosion resistance advantages over austenitic stainless steels. However, it is susceptible to embrittlement caused by factors such as grain growth, sigma phase formation, and carbide precipitation. This study investigates the stress corrosion cracking (SCC) behavior of AISI-409 ferritic stainless steel welded with AWS E316LT1-4 flux-cored wire, with heat inputs ranging from 400 J/mm to 805 J/mm. SCC tests were conducted by applying a constant load, followed by mechanical and microstructural analysis upon failure. Interestingly, higher heat input exhibited superior SCC resistance despite slower cooling rates compared to lower heat input. SCC initiated in the heat-affected zone (HAZ) and extended into the ferritic region. Photomicrographs depicted a ductile-to-brittle transition with reduced elongation values. Two distinct fracture regions were observed: dimples and cleavage facets, indicative of SCC-induced brittle fracture behavior. These findings provide insights into the SCC behavior of ferritic stainless steel, guiding the development of more resilient, corrosion-resistant materials for various industries. (author)