Cracking in laser additively manufactured W: Initiation mechanism and a suppression approach by alloying

Dianzheng Wang; Zhimin Wang; Kailun Li; Jing Ma; Wei Liu; Zhijian Shen

Materials & Design (Jan 2019)

Cracking in laser additively manufactured W: Initiation mechanism and a suppression approach by alloying

Dianzheng Wang,
Zhimin Wang,
Kailun Li,
Jing Ma,
Wei Liu,
Zhijian Shen

Affiliations

Dianzheng Wang: State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Beijing Hangxing Machinery Manufacture Limited Corporation, Beijing 100013, China
Zhimin Wang: Beijing Hangxing Machinery Manufacture Limited Corporation, Beijing 100013, China
Kailun Li: State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Jing Ma: State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Wei Liu: State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Corresponding author.
Zhijian Shen: State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden; Correspondence to: Z. Shen, State Ley Laboratory of New Ceramic and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

Journal volume & issue: Vol. 162
pp. 384 – 393

Abstract

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Cracking represents the main challenge for exploiting tungsten in additive manufacturing. In this study, laser powder-bed-fusion technique was applied to additively manufacture tungsten. In the built bulks, the grain boundaries were found to be rich in nanoscale gas pores. On the basis of that, a nanopore segregation induced cracking initiation mechanism was proposed. In order to control cracks, W-6wt.%Ta alloy was produced and the cracking suppression mechanism was investigated. The W-6Ta alloy is characterized by a submicron intragranular cellular structure, which composed large amount of interlocked dislocations as revealed by transmission electron microscopy. Owing to the cellular structure, the nanopores were trapped inside grains, which can reduce the cracking possibility. Moreover, the W-Ta alloy possesses higher strength (by 17%) and higher energy dissipation rate (by 52%) than pure tungsten, which both are beneficial for crack reduction. Keywords: Additive manufacturing, W, W-Ta alloy, Cracking mechanism, Cellular structure

Published in Materials & Design

ISSN: 0264-1275 (Print); 1873-4197 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/materials-and-design

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