Laser powder bed fabrication of nickel-base superalloys: Influence of parameters; characterisation, quantification and mitigation of cracking

Research output: Chapter in Book/Report/Conference proceedingConference contribution

76 Citations (Scopus)

Abstract

The use of a selective laser melting (SLM) powder-bed method to manufacture Ni-based superalloys components provides an economic approach for low production run components that operate under a high-temperature and stress environment. A major concern with the SLM of precipitation hardenable Ni-based superalloys is their high susceptibility to cracking, which has been heavily documented in the field of welding. Weld cracking may occur either during processing (hot cracking, liquation cracking and ductility-dip cracking) or during the post weld heat-treatment stage (strain-age cracking). Due to the complex thermal history of SLM fabricated material there is the potential for all of these mechanisms to be active. In this investigation, cuboidal coupons of the Ni-based superalloy CM247LC were fabricated by the SLM of argon gas atomised powder. Parametric studies were performed to investigate the influence of the process parameters (laser scan speed, power and scan spacing) on the cracking density and morphology through conducting a stereological study of scanning electron microscope (SEM) micrographs. Further microstructural evidence is presented, illustrating the different crack morphologies observed as well as suggesting the responsible mechanisms. Finally a postfabrication Hot Isostatic Pressing (HIP) treatment was performed to investigate its utility in 'healing' the internal cracks, and providing a route to retro-fix the cracking problem in the heat treatment stage of production. The findings highlight the need for process models of the SLM method in order to understand the thermal history and the laser fabricated structures observed.

Original languageEnglish
Title of host publicationSuperalloys 2012
PublisherJohn Wiley & Sons
Pages577-586
Number of pages10
ISBN (Print)9780470943205
DOIs
Publication statusPublished - 2 Oct 2012
Event12th International Symposium on Superalloys, Superalloys 2012 - Seven Springs, PA, United States
Duration: 9 Sep 201213 Sep 2012

Conference

Conference12th International Symposium on Superalloys, Superalloys 2012
Country/TerritoryUnited States
CitySeven Springs, PA
Period9/09/1213/09/12

Keywords

  • CM247LC
  • Microstructure Alloy Index Keywords
  • Ni-based Superalloys
  • Selective Laser Melting

ASJC Scopus subject areas

  • Materials Science(all)

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