Role of martensite decomposition in tensile properties of selective laser melted Ti-6Al-4V

Sheng Cao, Ruikun Chu, Xigen Zhou, Kun Yang, Qingbo Jia, Chao Voon Samuel Lim, Aijun Huang, Xinhua Wu

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The as-Selective Laser Melted (as-SLMed) Ti-6Al-4V generally has a martensitic microstructure. In the present study, martensite decomposition was investigated in various annealed samples by XRD, SEM and TEM. It has been found that annealing at 700 °C or 800 °C for 2 h was not sufficient to obtain a fully decomposed microstructure. The amount of martensite did reduce greatly and volume fraction of β phase increased significantly when the annealing temperature increased from 700 to 800 °C. However, the best combination of mechanical property was not obtained. It is to be noted that annealing at 800 °C for 2 h is widely used for SLMed Ti-6Al-4V as reported in literature. Detailed SEM and TEM analysis revealed the presence of residual martensite containing twins and a high density of dislocations even in the 800 °C/2 h annealed sample. The twin was determined as {101¯1} <101¯2> type, which are retained twin formed in martensitic transformation during the cooling in SLM. Annealing at 800 °C for 6 h or more provided a fine equilibrium α + β microstructure, which provided a strong and ductile SLMed Ti-6Al-4V.

Original languageEnglish
Pages (from-to)357-363
Number of pages7
JournalJournal of Alloys and Compounds
Volume744
DOIs
Publication statusPublished - 5 May 2018

Keywords

  • Laser processing
  • Metals
  • Scanning and transmission electron microscopy
  • X-ray diffraction

Cite this

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title = "Role of martensite decomposition in tensile properties of selective laser melted Ti-6Al-4V",
abstract = "The as-Selective Laser Melted (as-SLMed) Ti-6Al-4V generally has a martensitic microstructure. In the present study, martensite decomposition was investigated in various annealed samples by XRD, SEM and TEM. It has been found that annealing at 700 °C or 800 °C for 2 h was not sufficient to obtain a fully decomposed microstructure. The amount of martensite did reduce greatly and volume fraction of β phase increased significantly when the annealing temperature increased from 700 to 800 °C. However, the best combination of mechanical property was not obtained. It is to be noted that annealing at 800 °C for 2 h is widely used for SLMed Ti-6Al-4V as reported in literature. Detailed SEM and TEM analysis revealed the presence of residual martensite containing twins and a high density of dislocations even in the 800 °C/2 h annealed sample. The twin was determined as {101¯1} <101¯2> type, which are retained twin formed in martensitic transformation during the cooling in SLM. Annealing at 800 °C for 6 h or more provided a fine equilibrium α + β microstructure, which provided a strong and ductile SLMed Ti-6Al-4V.",
keywords = "Laser processing, Metals, Scanning and transmission electron microscopy, X-ray diffraction",
author = "Sheng Cao and Ruikun Chu and Xigen Zhou and Kun Yang and Qingbo Jia and Lim, {Chao Voon Samuel} and Aijun Huang and Xinhua Wu",
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Role of martensite decomposition in tensile properties of selective laser melted Ti-6Al-4V. / Cao, Sheng; Chu, Ruikun; Zhou, Xigen; Yang, Kun; Jia, Qingbo; Lim, Chao Voon Samuel; Huang, Aijun; Wu, Xinhua.

In: Journal of Alloys and Compounds, Vol. 744, 05.05.2018, p. 357-363.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Cao, Sheng

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AU - Zhou, Xigen

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AU - Lim, Chao Voon Samuel

AU - Huang, Aijun

AU - Wu, Xinhua

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AB - The as-Selective Laser Melted (as-SLMed) Ti-6Al-4V generally has a martensitic microstructure. In the present study, martensite decomposition was investigated in various annealed samples by XRD, SEM and TEM. It has been found that annealing at 700 °C or 800 °C for 2 h was not sufficient to obtain a fully decomposed microstructure. The amount of martensite did reduce greatly and volume fraction of β phase increased significantly when the annealing temperature increased from 700 to 800 °C. However, the best combination of mechanical property was not obtained. It is to be noted that annealing at 800 °C for 2 h is widely used for SLMed Ti-6Al-4V as reported in literature. Detailed SEM and TEM analysis revealed the presence of residual martensite containing twins and a high density of dislocations even in the 800 °C/2 h annealed sample. The twin was determined as {101¯1} <101¯2> type, which are retained twin formed in martensitic transformation during the cooling in SLM. Annealing at 800 °C for 6 h or more provided a fine equilibrium α + β microstructure, which provided a strong and ductile SLMed Ti-6Al-4V.

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