Study of the notch fatigue behaviour under biaxial conditions of maraging steel produced by selective laser melting. (October 2022)

• Record Type: Journal Article
• Authors: Cruces, A.S.; Exposito, A.; Branco, R.; Borrego, L.P.; Antunes, F.V.; Lopez-Crespo, P.
• Is Part Of: Theoretical and applied fracture mechanics. Volume 121(2022)
• Publication Date: 2022-10
• Subjects: Multiaxial fatigue -- Maraging steel -- Critical plane methods; Fracture mechanics -- Periodicals; 620.1126
• DOI: 10.1016/j.tafmec.2022.103469
• Languages: English
• ISSNs: 0167-8442

Abstract

Highlights: Study of the fatigue propagation from notches of AISI 18Ni300 maraging steel. Analysis performed on the maraing steel fabricated via additive manufacturing process (laser-beam powder bed fusion). The investigation is focused on cracks propagating from two different notch sizes and without notch under three different biaxial loading paths. Combination of critical plane models with theory of critical distances allows effective characterisation. The quality of the predictions is analysed both in terms of the fatigue life and the cracking orientation. Abstract: The current work aims to characterise the fatigue behaviour of an additively manufactured maraging steel, AISI 18Ni300. This is a class of high-strength steel widely used in biomedical, aircraft, aerospace, offshore, and military industries thanks to its good performance in terms of strength, toughness, ductility, dimensional stability, and weldability. Laser-beam powder bed fusion (additive manufacturing) is used to fabricate this type of steel and endows it with properties that make it an excellent candidate for producing prosthetic parts, thereby facilitating a reduction in manufacturing material consumption, labour, and machining time. Given the wide range of loads biomedical components are often subjected to, the current study focused on the multiaxial behaviour of this type of steel. To this end, Fatemi–Socie (FS) and Smith–Watson–Topper (SWT) critical plane methods combined with the theory of critical distances were applied to predict the fatigue life and cracking orientation of this material, with and without notches, under three biaxial loading scenarios. Cylindrical specimens were used and these were fabricated on the base plate in the vertical orientation using a linear printing system equipped with a Nd:YAG fibre laser. The building strategy involved the deposition of 40 μm thick layers at a scan speed of 800 mm/s. The two critical plane models returned good results at low life cycle fatigue but the FS model obtained better results at high life cycle fatigue. Regarding the crack angles, SWT model produced the best predictions.