Micro- and macro-structural heterogeneities in 316L stainless steel prepared by electron-beam melting

Jon Olsén, Zhijian Shen, Leifeng Liu, Andrey Koptyug, Lars Erik Rännar

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

This is a study of the micro- and macrostructural variations in samples of stainless steel with the overall composition of the grade 316L, produced using electron beam melting. Electron beam melting is one of the processing methods under consideration for manufacturing some of the International Thermo- Nuclear Experimental Reactor In-Vessel components. Therefore further studies of the homogeneity of the material were conducted. Electron beam melting results in a complicated thermal history of the manufactured part giving a significant impact on the microstructure. A cellular structure that is often observed in samples prepared by selective laser melting was found in the top layers of the specimens. Further down, the structure changed until the cellular structure was almost non-existing, and the grain boundaries had become more pronounced. This revelation of a heterogeneous structure throughout the entire part is crucial for large-scale industrial applications like the Thermo- Nuclear Experimental Reactor to make sure that it is understood that the properties of the material might not be the same at every point, as well as to assure that the correct post-treatment is done. It is also exposed that a significant part of this change is due to molybdenum redistribution inside the sample when it diffuses from the cell boundaries into the cells, and into bigger agglomerates in the grain boundaries. This diffusion seems not to affect the microhardness of the samples.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalMaterials Characterization
Volume141
DOIs
Publication statusPublished - Jul 2018
Externally publishedYes

Keywords

  • 316L stainless steel
  • Additive manufacturing
  • Electron beam melting
  • Heterogeneous material
  • Microstructure

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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