Fatigue resistance of AL6XN super-austenitic stainless steel welded with electromagnetic interaction of low intensity during GMAW

Plates of AL6XN super-austenitic stainless steel with a single-V groove preparation were gas metal arc welded (GMAW) with and without electromagnetic interaction of low intensity (EMILI) during welding using an ER-NiCrMo3 filler wire and 97% Ar + 3% N 2 as shielding gas. The fatigue behavior of the welded joints was evaluated under constant stress amplitude (Δσ/2) between 135 and 170 MPa ( R = 0.1) and uniaxial load. The Wöhler diagram indicated that for stress amplitude of 170 MPa, 4.19 × 10 5 and 2.96 × 10 5 cycles were required for failure without and with EMILI, respectively, whereas for 135, 140, and 145 MPa, 1 × 10 7 cycles were reached without failure. Welding with EMILI was found to have a positive effect nearby fatigue limit. Observation of the fractures indicates that failures started on the surface of the specimens in the weld metal (WM) due to the stress concentration induced by the abundant presence of precipitates located along the interdendritic spaces in this zone of the welded joint. These particles acted as crack-nucleating agents and then the crack propagated throughout the WM. Fractography revealed brittle fracture associated to cleavage.