The Smith-Watson-Topper parameter and fracture surface topography relationship for additively manufactured 18Ni300 steel subjected to uniaxial variable-amplitude loading

In this paper, the association between Smith-Watson-Topper (SWT) parameter and fracture surface topography is studied in additively manufactured maraging steel exposed to variable-amplitude fatigue loading. The postfailure fracture surfaces were examined using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focal point is on the correspondence between fatigue characteristics, articulate by the SWT parameter, and the fracture surface topography features, represented by areal, volume, and fractal dimension parameters. A fatigue life prediction model based on SWT and fracture surface topography factors is proposed. The presented model expresses good compliance with fatigue test results. This model can be useful for post-mortem analysis of engineering elements under variable-amplitude loading fatigue, especially for materials produced by additive manufacturing (AM).