Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution

No underwater laser additive manufacturing technology has been reported. In this paper, the underwater thin-walled Ti-6Al-4V part was built firstly by underwater laser metal deposition (ULMD), and the formability, grain growth and microstructure transformation were investigated. The stable local dry...

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Main Authors: Yunlong Fu, Ning Guo, Guanghui Wang, Mengqiu Yu, Qi Cheng, Di Zhang
Format: Article
Language:English
Published: Elsevier 2021-01-01
Series:Materials & Design
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S0264127520307310
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author Yunlong Fu
Ning Guo
Guanghui Wang
Mengqiu Yu
Qi Cheng
Di Zhang
author_facet Yunlong Fu
Ning Guo
Guanghui Wang
Mengqiu Yu
Qi Cheng
Di Zhang
author_sort Yunlong Fu
collection DOAJ
description No underwater laser additive manufacturing technology has been reported. In this paper, the underwater thin-walled Ti-6Al-4V part was built firstly by underwater laser metal deposition (ULMD), and the formability, grain growth and microstructure transformation were investigated. The stable local dry cavity and the shielding-gas flow layer surrounding the deposited layer formed during the ULMD process utilizing an improved ULMD nozzle, generating the uniform thin-walled part without cracks and pores. Columnar β-grains, growing epitaxially opposite to the heat flow direction, were observed in the whole ULMD part, and the grain size increased firstly and then reduced with increasing the deposition layer, attributed to the comparative growth and decreasing cooling rate. The water cooling effect suppressed the formation of equiaxed β grains that only formed in the top region of ULMD part. For the microstructures of ULMD sample, only acicular martensites α' with different size scales formed in the bottom region, and martensites α' were replaced gradually by α phase with lamellar, lathy and blocky shapes with increasing the building height, except the top region because the absence of multiple thermal cycles. The larger cooling rate promoted the formation of α' martensite and decreased the width of α lath of ULMD part.
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spelling doaj.art-c325bfa156cd4354bc68cccd9da603be2022-12-21T20:45:14ZengElsevierMaterials & Design0264-12752021-01-01197109196Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolutionYunlong Fu0Ning Guo1Guanghui Wang2Mengqiu Yu3Qi Cheng4Di Zhang5State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China; Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, ChinaState Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China; Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China; Shandong Institute of Shipbuilding Technology, Weihai 264209, China; Corresponding author at: No.2 Wenhuaxi Road, Weihai 264209, China.Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, ChinaShandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, ChinaShandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, ChinaShandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, ChinaNo underwater laser additive manufacturing technology has been reported. In this paper, the underwater thin-walled Ti-6Al-4V part was built firstly by underwater laser metal deposition (ULMD), and the formability, grain growth and microstructure transformation were investigated. The stable local dry cavity and the shielding-gas flow layer surrounding the deposited layer formed during the ULMD process utilizing an improved ULMD nozzle, generating the uniform thin-walled part without cracks and pores. Columnar β-grains, growing epitaxially opposite to the heat flow direction, were observed in the whole ULMD part, and the grain size increased firstly and then reduced with increasing the deposition layer, attributed to the comparative growth and decreasing cooling rate. The water cooling effect suppressed the formation of equiaxed β grains that only formed in the top region of ULMD part. For the microstructures of ULMD sample, only acicular martensites α' with different size scales formed in the bottom region, and martensites α' were replaced gradually by α phase with lamellar, lathy and blocky shapes with increasing the building height, except the top region because the absence of multiple thermal cycles. The larger cooling rate promoted the formation of α' martensite and decreased the width of α lath of ULMD part.http://www.sciencedirect.com/science/article/pii/S0264127520307310Underwater laser metal depositionTi-6Al-4VFormabilityGrain growthMicrostructure evolution
spellingShingle Yunlong Fu
Ning Guo
Guanghui Wang
Mengqiu Yu
Qi Cheng
Di Zhang
Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
Materials & Design
Underwater laser metal deposition
Ti-6Al-4V
Formability
Grain growth
Microstructure evolution
title Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
title_full Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
title_fullStr Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
title_full_unstemmed Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
title_short Underwater additive manufacturing of Ti-6Al-4V alloy by laser metal deposition: Formability, gran growth and microstructure evolution
title_sort underwater additive manufacturing of ti 6al 4v alloy by laser metal deposition formability gran growth and microstructure evolution
topic Underwater laser metal deposition
Ti-6Al-4V
Formability
Grain growth
Microstructure evolution
url http://www.sciencedirect.com/science/article/pii/S0264127520307310
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