Inverse columnar-equiaxed transition (CET) in 304 and 316l stainless steels melt by electron beam for additive manufacturing (AM)

Miyata, Yuichiro; Okugawa, Masayuki; Koizumi, Yuichiro et al.

Crystals, 2021, 11(8), 856

Number of Access:546（2025-08-14 02:42 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/89926

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Title
Inverse columnar-equiaxed transition (CET) in 304 and 316l stainless steels melt by electron beam for additive manufacturing (AM)
Creator
CreatorName
Miyata, Yuichiro
NRID
1000070847160 1000070847160
ORCID
0000-0002-6844-6856 0000-0002-6844-6856
researchmap permalink
masayuki.okugawa masayuki.okugawa
Scopus Author ID
57202824128 57202824128
CreatorName
Okugawa, Masayuki
NRID
1000010322174 1000010322174
ORCID
0000-0001-7061-7135 0000-0001-7061-7135
researchmap permalink
YuichiroKoizumi YuichiroKoizumi
Scopus Author ID
57202772340 57202772340
CreatorName
Koizumi, Yuichiro
NRID
1000030243182 1000030243182
ORCID
0000-0001-8052-1698 0000-0001-8052-1698
researchmap permalink
read0013987 read0013987
Scopus Author ID
7403896013 7403896013
CreatorName
Nakano, Takayoshi
Subject
304 stainless steel
316L stainless steel
Additive manufacturing
Computational thermal-fluid dynamics simulation
Electron-beam melting
Powder-bed fusion
Description
Miyata Y., Okugawa M., Koizumi Y., et al. Inverse columnar-equiaxed transition (CET) in 304 and 316l stainless steels melt by electron beam for additive manufacturing (AM). Crystals 11, 856 (2021); https://doi.org/10.3390/cryst11080856.
Abstract
According to Hunt’s columnar-to-equiaxed transition (CET) criterion, which is generally accepted, a high-temperature gradient (G) in the solidification front is preferable to a low G for forming columnar grains. Here, we report the opposite tendency found in the solidification microstructure of stainless steels partially melted by scanning electron beam for powder bed fusion (PBF)-type additive manufacturing. Equiaxed grains were observed more frequently in the region of high G rather than in the region of low G, contrary to the trend of the CET criterion. Computational thermal-fluid dynamics (CtFD) simulation has revealed that the fluid velocity is significantly higher in the case of smaller melt regions. The G on the solidification front of a small melt pool tends to be high, but at the same, the temperature gradient along the melt pool surface also tends to be high. The high melt surface temperature gradient can enhance Marangoni flow, which can apparently reverse the trend of equiaxed grain formation.
Publisher
MDPI
Source Title
Crystals
Volume (Issue)
11(8)
Page
856
Date of Issued
2021-07-23
Language
English
Handle URL
https://hdl.handle.net/11094/89926
eISSN
20734352
Relation.isIdenticalTo
DOI (Publisher Version)
https://doi.org/10.3390/cryst11080856
Access Rights
open access
CopyRight
This article is licensed under a Creative Commons Attribution 4.0 International License.
oaire:version
Version of Record
Category
学術雑誌論文 Journal Article