Title: Role of scan strategies and heat treatment on grain structure evolution in Fe-Si soft magnetic alloys made by laser-powder bed fusion

Abstract

A major goal in printing soft magnetic Fe-Si steels using additive manufacturing is to take advantage of the potential for complex geometric designs and site-specific grain control. One major step in the processing of these alloys is understanding how processing parameters might impact how the as-built microstructure responds to annealing (i.e. the annealing response). The impact of scan strategy on the annealing response for thin wall geometries is specifically explored. Two scan strategies were explored for a thin wall geometry that produced a strongly columnar grain structure and equiaxed grain structure. Additionally, samples from both scan strategies annealed at 1200 °C showed a marked difference in annealing response with the more equiaxed sample seeing full recrystallization and grain growth, while the more columnar grain structure saw little change in microstructure. After analysis through characterization techniques and thermal-mechanical simulations Differences in internal energy within the grains were ruled out because calculated GND density values were similar for both samples. The formation of secondary particles was ruled out as a contributing factor due to the type of oxide formations and their size. It was concluded that the contributing factor to the difference in the annealing response were a difference in the resultingmore » grain size and the density of high angle grain boundaries. These two differences were largely attributed to differences in the thermal gradient conditions due to grains preferentially growing in the direction of the steepest thermal gradient.« less

Authors:

Haines, Michael ^[1]; List III, Fred  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-3909-5890"

Carver, Keith  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-4483-6929"

Leonard, Donovan  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-1806-4526"

Plotkowski, Alex  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-5471-8681"

Fancher, Christopher  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-3952-5168"

Dehoff, Ryan  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-9456-9633"

Babu, Sudarsanam ^[3]

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+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States); Univ. of New South Wales, Sydney, NSW (Australia)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Fri Dec 24 00:00:00 EST 2021

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE); US Office of Naval Research (ONR)

OSTI Identifier:

1841490

Alternate Identifier(s):

OSTI ID: 1839153

Grant/Contract Number:  

AC05-00OR22725; N00014-18-1-2794

Resource Type:

Accepted Manuscript

Journal Name:

Additive Manufacturing

Additional Journal Information:

Journal Volume: 50; Journal Issue: 2; Journal ID: ISSN 2214-8604

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Laser powder bed fusion; Soft magnetic steels; Additive manufacturing; Annealing