Fatigue Performance of Wire Arc Additively Manufactured ER70S-6 and ER80S-Ni1

The fatigue performance of the machined and as-built surface finishes of wire arc additively manufactured (WAAM) steels must be understood to advance their integration into cyclically loaded applications. To assess this performance, specimens were fabricated by WAAM using ER70S-6 and ER80S-Ni1 feedstock. ER70S-6 and ER80S-Ni1 specimens were fabricated at two and three interpass temperatures, respectively. Thirty-six as-built surface finish specimens were tested at four stress ranges, and 16 fully machined specimens were tested at two stress ranges to generate stress–life curves. All machined specimens were runouts. Despite slight variances in the measured surface roughness of the different specimen types, the performance of all as-built specimens was similar. A regression was performed for all as-built data, excluding runouts. The resulting slope, m = 4.1, differed from the slopes specified by the AASHTO and EN 1993-1-9 of m = 3. When the slope of the as-built regression was forced to m = 3, the regression exceeded AASHTO fatigue detail Category D and fell on EN 1993-1-9 FAT 80. The results demonstrated that the fatigue performance of WAAM ER70S-6 and ER80S-Ni1 can be influenced by surface finishing, but the impacts of wire type and interpass temperature are negligible.