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Scan strategy induced microstructure and consolidation variation in the laser-powder bed fusion (L-PBF) additive manufacturing of low alloy 20MnCr5 steel

Yang, X, Gibbons, GJ, Tanner, DA, Li, Z, Wilson, P, Williams, MA and Kotadia, HR (2023) Scan strategy induced microstructure and consolidation variation in the laser-powder bed fusion (L-PBF) additive manufacturing of low alloy 20MnCr5 steel. Materials and Design, 232. ISSN 0264-1275

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Abstract

The paper focuses on the effect of the scanning strategies on the microstructural evolution, defect formation, and macro-hardness performance of laser-powder bed fusion (L-PBF) produced samples of low alloy 20MnCr5 steel. Respect to the scanning strategies, advanced characterization techniques were employed to study (i) as-built microstructure, (ii) inclusion size and distribution, and (iii) details of compositional variation around porosity and within the build. Microstructural characterization shows that the chessboard scanning strategy can provide a favorable microstructure for the improvement of mechanical performance. However, macro-hardness results show a lower mechanical performance compared to the linear scanning strategy samples, which is contradicted by the improved microstructure. Experimental results reveal that the chessboard scanning strategy promotes the oxidation reaction and in-situ oxide (SiO2) formation in L-PBF, which leads to significant defect formation due to the excessive thermal profile from the overlap of the laser. This has been validated through finite element analysis and thermodynamic computation. The advantages of microstructural improvement using the chessboard strategy can only be realized with strict control of the metallurgical quality during the L-PBF process. Thermal profile optimization and oxygen elimination during the L-PBF process could be critical for the improved metallurgical quality and superior mechanical performance of the as-built components.

Item Type: Article
Uncontrolled Keywords: 0910 Manufacturing Engineering; 0912 Materials Engineering; 0913 Mechanical Engineering; Materials
Subjects: T Technology > TJ Mechanical engineering and machinery
T Technology > TS Manufactures
Divisions: Engineering
Publisher: Elsevier BV
SWORD Depositor: A Symplectic
Date Deposited: 27 Oct 2023 15:11
Last Modified: 27 Oct 2023 15:15
DOI or ID number: 10.1016/j.matdes.2023.112160
URI: https://researchonline.ljmu.ac.uk/id/eprint/21756
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