Effect of a magnetic field applied during fusion welding on the fatigue damage of 2205 duplex stainless steel joints

•Magnetic field applied during welding of 2205 duplex steel improved fatigue resistance.•Magnetic field induced ferrite grain refinement, high regenerated austenite in the HAZ.•Improved microstructure increased number of microstructure barriers for crack growth.•Crack initiation needed more load cycles on samples welded under 3 mT magnetic field.•More plastic deformation was induced on austenite before fatigue crack initiation.