Microstructure and Fatigue Life of Surface Modified PBF-LB Manufactured Maraging Steel

Abstract

The present work was aimed at increasing the fatigue life of laser powder bed fusion manufactured maraging steel (MS) using surface modification. Samples were manufactured to investigatethe mechanical properties of the material with two types of heat treatment routes that were both subjected to severe shot peening (SSP). In addition, bending fatigue testing was utilized to reveal theeffect of shot peening (SP) and SSP on fatigue resistance of the MS. Microhardness profiles weremeasured near the surface and electron backscatter diffraction analysis was used for microstructuralanalysis. A thin layer of austenite was noted on the surface making it a softer section, which SP orSSP was able to transform. The fatigue life of the MS was notably icreased by the SP processing andeven greater improvement was achieved with the SSP, which raised the fatigue limit of the materialfrom 200 MPa to nearly 500 MPa.