Crack-free in situ heat-treated high-alloy tool steel processed via laser powder bed fusion: microstructure and mechanical properties

Simon Bergmueller*, Lukas Kaserer, Lorenz Fuchs, Jakob Braun, Nikolaus Weinberger, Ilse Letofsky-Papst, Gerhard Leichtfried

*Korrespondierende/r Autor/-in für diese Arbeit

Publikation: Beitrag in einer FachzeitschriftArtikelBegutachtung


In this study, high-alloy tool steel S390 was processed crack-free and dense for the first time using laser powderbed fusion (LPBF). The resulting mechanical properties and microstructure of the LPBF steel parts were investigated.High-alloy tool steels, such as high-performance high-speed Boehler S390 steel (containing 1.64 wt% C andW, Mo, V, Co, and Cr in the ratio 10:2:5:8:5 wt%), are prone to cracking when processed using LPBF because thesesteels have high carbon and carbide-forming alloying elements content. Cracks are induced by thermal stressesand solid-phase transformation, combined with weak grain boundaries caused by segregated primary carbides.Substrate plate heating reduces thermal stresses and enables in situ heat treatment, thus modulating solid-phasetransformation and carbide precipitation and preventing cracking during cooling. The resulting microstructure,precipitations, and mechanical properties of the as-built LPBF specimens, which were in situ heat-treated at 800C, and the conventionally post-heat-treated specimens were assessed using optical microscopy, scanning electronmicroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatterdiffraction, X-ray diffraction, hardness testing, bending testing, and density measurement. In situ heat treatmentimpacts microstructure, precipitation behavior, and solid-phase transformation, causing a change in the microstructureof the material along the build direction due to different thermal histories. The as-built specimensexhibit a hardness gradient along the build direction of 500 HV1 to 800 HV1 in the top layer. The average bending
PublikationsstatusVeröffentlicht - 2022

ASJC Scopus subject areas

  • Allgemeine Materialwissenschaften
  • Allgemein

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)


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