Plane-strain fracture toughness of thin additively manufactured maraging steel samples

This study aimed to evaluate the aging effects on mechanical properties of 18Ni (300) maraging steel processed by additive manufacturing powder bed fusion and subjected to different aging conditions. The aging temperatures were 470 degrees C, 510 degrees C, and 530 degrees C, with exposure times ranging from 0.33 to 96 h, followed by air cooling. Despite the layer-by-layer material consolidation mechanism, weak preferred orientation was found in the asbuilt condition; moreover, only martensite and austenite were found in the X-ray diffraction results. This alloy showed a steep increase in hardness, compressive strength, and tensile strength, while the work-hardening ability decreased with aging. Despite using thin single-edge bending samples (5 mm), the plane-strain fracture toughness (K-IC) size requirement was met, and valid K-IC results were 49 similar to 64 MPa root m. This result could help design new additive manufacturing applications of high-strength steel, such as thin-walled, lattice structures, and reduced cross-section parts projected to minimize weight in different industries.