Journal Article

PUBDB-2025-05144

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Microstructural evolution in high-temperature direct aging on PBF-LB 15-5PH stainless steel

Kultz Unti, L. F. (Corresponding author)Extern* ; Aota, L. S. ; Lopes, E. S. N.Extern* ; Ribamar, G. G.Extern*Hereon* ; Schell, N.HZG*Hereon* ; Oliveira, J. P.Extern* ; Gault, B. ; Avila, J. A.Extern* ; Jardini, A. L. ; Zilnyk, K. D.Extern*

2026
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.actamat.2025.121747

Abstract: High solidification rates and in situ heat treatments are commonly found in additive manufacturing (AM) ofsteels, resulting in a complex and far-from-equilibrium microstructure. Therefore, standard post-processing heattreatments commonly applied to wrought steels can favor the occurrence of different phenomena and can changethe phase transformation sequence, due to the unique microstructure obtained by powder bed fusion – laserbeam (PBF-LB). This work reports the microstructural evolution of 15-5 precipitation hardening (PH) stainlesssteel manufactured by PBF-LB during direct aging heat treatments at 621 ◦C (AMS H1150 standard condition), aroute used to increase fracture toughness due to the martensite reversion and precipitates coarsening. Thereversion of martensite into a Ni-rich austenite, predicted by kinetic calculations, was confirmed by high-energyX-ray diffraction (HE-XRD), being preferentially nucleated close to the copper-rich precipitates (CRPs), whichcan act as a preferential nucleation site. CRPs presented an oval shape, as confirmed by electronic microscopy(SEM and TEM) and atom probe tomography (APT). Fast Fourier transform (FFT) analysis of high-resolution TEM(HR-TEM) images suggests CRPs still present the metastable untwined 3R-type structure after 8 h, rather than themost stable FCC structure. The presence of retained austenite, inherent to PBF-LB-processed PH steels, affects theCRPs evolution in different phases, and the CRPs themselves act as nucleation sites for Nb(C,N) secondaryprecipitation. These findings emphasize the necessity of microstructure-oriented heat treatment routes to unlockthe full potential of additively manufactured PH stainless steels.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. Helmholtz-Zentrum Hereon (Hereon)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
2. FS-Proposal: I-20210563 (I-20210563) (I-20210563)

Experiment(s):

1. PETRA Beamline P07 (PETRA III)

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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