Abstract
This investigation concerns about of fatigue behavior under controlled loading and under strain control for hybrid specimens with parts produced with conventional processes in steel AISI H13 and the stainless steel AISI 420 and the rest part produced by laser powder bed fusion in AISI 18Ni300 steel. The controlled loading tests were performed in constant and variable amplitude. Fatigue failure of hybrid samples occurs mostly in laser-melted parts, initiated around the surface, in many cases with multi-nucleation and propagated predominantly between the deposited layers. Fatigue strength of hybrid parts, tested under displacement control is similar, but for specimens tested under load control the fatigue strength the fatigue strength of hybrid specimens is progressively lesser than laser powder bed fusion samples. Despite a tendency to obtain conservative predictions, Miner’s law predicts reasonably the fatigue lives under block loadings. The interface between materials presented an excellent joining and fatigue strength because the fatigue failure of hybrid samples occurred mostly in laser melted parts out of the interface.
Highlights
The results indicate that the fatigue strength is strongly affected by defects inherent to the Laser powder bed fusion (LPBF) process
The objective of this work was to investigate the fatigue performance of hybrid specimens obtained by LPBF maraging steel implants into hot working tools and stainless steels substrates
The hybrid samples have higher global stiffness than the LPBF only specimens, as a consequence of the recorded strain to be an average value in the region of the interface between the ends of the extensometer (12.5-gauge length)
Summary
Laser powder bed fusion (LPBF) is a technology of rapid manufacturing that builds metal parts layer by-layer using metal powders [1] fused by a high-power laser. This technique is increasingly used to obtain components with complex shapes namely in automotive, aerospace, medical and of injection molds industries. Several studies have been previous published on the area of LPBF technology using different metal powders, for example, the fabricating of iron-base alloys [2,3,4,5], nickel-base alloys [6,7], copper-base alloys [8] and titanium-base alloys [9]
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