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A comprehensive study on microstructure and tensile behaviour of a selectively laser melted stainless steel

Qiu, Chunlei ORCID: https://orcid.org/0000-0002-1899-3229, Al Kindi, Mohammed, Aladawi, Aiman Salim and Al-Hatmi, Issa 2018. A comprehensive study on microstructure and tensile behaviour of a selectively laser melted stainless steel. Scientific Reports 8 (1) , 7785. 10.1038/s41598-018-26136-7

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Abstract

316L stainless steel samples have been prepared by selective laser melting (SLM) using a pulsed laser mode and different laser powers and scanning patterns. The as-fabricated samples were found to be dominated by clusters of nano-sized γ needles or cells. TEM imaging shows that these needles contain a high population of dislocations while TEM-EDX analysis reveals high chemical homogeneity throughout the as-fabricated samples as evidenced by the fact that there is even no micro-/nano-segregation at interfaces between neighbouring γ needles. The good chemical homogeneity is attributed to the extremely high cooling rate after SLM (>106 °C/s) and the formation of Si- and Mn-oxides that distribute randomly in the current samples. The laser-processed samples show both superior strength and ductility as compared with conventionally manufactured counterparts. TEM examination on the deformed specimens reveals a significantly high density of dislocations and a great number of twinning within nano-needles, suggesting that the plastic deformation has been governed by both gliding of dislocations and twinning deformation, which is believed to be responsible for the simultaneous acquisition of superior strength and ductility. Finally, laser power shows a much more dominant role than laser scanning pattern in porosity and grain size development for the SLM-processed 316L stainless steel samples.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Additional Information: This article is licensed under a Creative Commons Attribution 4.0 International License
Publisher: Nature Publishing Group
ISSN: 2045-2322
Date of First Compliant Deposit: 24 January 2019
Date of Acceptance: 3 May 2018
Last Modified: 05 May 2023 13:35
URI: https://orca.cardiff.ac.uk/id/eprint/118586

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