Microstructural characterization and properties of selective laser melted maraging steel with different build directions

Chaolin Tan, Kesong Zhou, Min Kuang, Wenyou Ma, Tongchun Kuang

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)
111 Downloads (Pure)

Abstract

A nearly fully dense grade 300 maraging steel was fabricated by selective laser melting (SLM) additive manufacturing with optimum laser parameters. Different heat treatments were elaborately applied based on the detected phase transformation temperatures. Microstructures, precipitation characteristics, residual stress and properties of the as-fabricated and heat-treated SLM parts were systematically characterized and analyzed. The observed submicron grain size (0.31 μm on average) suggests an extremely high cooling rate up to 107 K/s. Massive needle-shaped nanoprecipitates Ni3X (X = Ti, Al, Mo) are clearly present in the martensitic matrix, which accounts for the age hardening. The interfacial relations between the precipitate and matrix are revealed by electron microscopy and illustrated in detail. Strengthening mechanism is explained by Orowan bowing mechanism and coherency strain hardening. Building orientation-based mechanical anisotropy, caused by ‘layer-wise effect’, is also investigated in as-fabricated and heat-treated specimens. The findings reveal that heat treatments not only induce strengthening, but also significantly relieve the residual stress and slightly eliminate the mechanical anisotropy. In addition, comprehensive performance in terms of Charpy impact test, tribological performance, as well as corrosion resistance of the as-fabricated and heat-treated parts are characterized and systematically investigated in comparison with traditionally produced maraging steels as guidance for industry applications.
Original languageEnglish
Pages (from-to)746-758
JournalScience and Technology of Advanced Materials
Volume19
Issue number1
Early online date28 Sep 2018
DOIs
Publication statusPublished - 31 Dec 2018

Keywords

  • Selective laser melting
  • additive manufacture
  • maraging steel
  • laser parameter
  • precipitate
  • heat treatment
  • anisotropy
  • coherent interface
  • Orowan mechanism
  • property

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