Lass, E.
, Campbell, C.
and Zhang, F.
(2020),
Nitrogen effects in additively manufactured martensitic stainless steels I: Conventional thermal processing and comparison with wrought, Metallurgical Transactions A-Physical Metallurgy and Materials Science, [online], https://doi.org/10.1007/s11661-020-05703-6, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928471
(Accessed July 17, 2024)
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Nitrogen effects in additively manufactured martensitic stainless steels I: Conventional thermal processing and comparison with wrought
Published
Author(s)
, ,
Abstract
The microstructures or additively manufactured (AM) precipitation-hardenable stainless steels 17-4 and 15-5 were investigated and compared to conventionally produced material. The residual nitrogen found in N2-atomized 17-4 powder feedstock is inherited by the additively produced material, and has dramatic effects on phase stability, microstructure, and microstructural evolution. Nitrogen is a known austenite stabilizing element, and the as-built microstructure of AM 17-4 can contain up to 90 % or more retained austenite, compared to the nearly 100 % martensite structure of wrought 17-4. Even after homogenization and solutionization heat treatments, AM 17-4 contains 5 % to 20 % retained austenite. In contrast, AM 15-5 and Ar-atomized AM 17-4 contain <5 % retained austenite in the as-built condition, and this level is further decreased following post-build thermal processing. Computational thermodynamics-based calculations do not seem to capture the extent of the experimentally observed depression in the martensite start temperature and martensite stability as a function of N-content. A significant increase in the volume fraction of fine-scale carbide precipitates attributed to the high N-content of AM 17-4 is also hypothesized to give rise to additional activation barriers for the dislocation motion required for martensite nucleation and subsequent growth. An increase in the volume fraction of carbide/nitride precipitates is also observed in AM 15-5, although they do not inhibit martensite formation to the extent observed in AM 17-4.Citation
Metallurgical Transactions A-Physical Metallurgy and Materials Science
Volume
51
Pub Type
Journals
Download Paper
Keywords
additive manufacturing, precipitation hardening, martensitic stainless steel, martensite, retained austenite
Citation
Issues
If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.
Created March 8, 2020, Updated October 12, 2021