Experimental study demonstrates distinct tension and torsion fatigue responses in 3D-printed super duplex stainless steel, indicating loading-dependent sensitivity to defects.
Key Points
To evaluate how laser powder bed fusion process parameters and resulting defect populations affect the monotonic tensile, tension fatigue, and torsional fatigue behaviors of single-phase SAF 2507 super duplex stainless steel.
Fabricated dense SAF 2507 specimens in two batches using distinct laser powder bed fusion process parameters.
Characterized microstructures and internal defect populations using X-ray computed tomography, electron backscatter diffraction, X-ray diffraction, and transmission electron microscopy.
Performed monotonic tensile tests and fully-reversed tension and torsion fatigue tests to determine crack initiation mechanisms and fatigue strength.
Both batches produced comparable defect sizes in the range of the grain size, but variations in defect density caused noticeable scatter in crack initiation sites.
Tensile fatigue performance and strength differed significantly based on whether cracks initiated at surface defects or grain boundaries.
Torsional fatigue behavior remained consistent across batches and was unaffected by changes in the crack initiation mechanism.