Effect of heat treatment on microstructure and electrochemical behavior of laser powder bed fusion hydride- dehydride ti-6al-4v alloy

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Description

In powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have... Show moreIn powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have
evaluated 3D-printing of spherical powder, very limited research has been carried out on
the processing of the non-spherical feedstock. This study is targeted specifically to the use
of non-spherical Ti-6Al-4V powders in the laser powder bed fusion (L-PBF) process. Two
different post-heat-treatments including hot isostatic pressing and solution treatment are
applied. The microstructure evaluation, potentiodynamic polarization, and electrochemical
impedance spectroscopy methods are used to characterize L-PBF processed and post-
treated specimens. Though as-built part exhibits anisotropic microstructure containing
acicular α′ martensite with trace amount of β phase, the heat-treated parts are composed of
α+β in which length and thickness of the α-lath depends on the treatment. The below β
transus heat treatment leads to the formation of a homogenized grain structures composed
of α+β. Electrochemical results show that the below β transus heat-treatment had a slight
positive effect on the improvement of corrosion resistivity (corrosion rate of 4.2×10-6 mmy-
1
, which is classified as an excellent ) compared to other conditions, which would be associated to the natural excellent corrosion resistance of Ti-6Al-4V alloy. This slight improvement can be ascribed by the slightly faster formation of a passive layer and its enhanced efficiency because of the presence of the fine-structured β phase in post heat- treated L-PBF processed Ti-6Al-4V alloy. Show less

Details
Department

MMAE / Mechanical, Materials, and Aerospace Engineering

Title

Effect of heat treatment on microstructure and electrochemical behavior of laser powder bed fusion hydride- dehydride ti-6al-4v alloy

Institution

Illinois Institute of Technology

Creator(s)

Delpazir, Melody Honardan

Advisor(s)

Mostafaei, Amir

Date

2022

Description

In powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have evaluated 3D-printing of... Show moreIn powder bed additive manufacturing, feedstock and processing have an impact onfinal microstructure and properties of 3D-printed parts. While numerous studies have evaluated 3D-printing of spherical powder, very limited research has been carried out on the processing of the non-spherical feedstock. This study is targeted specifically to the use of non-spherical Ti-6Al-4V powders in the laser powder bed fusion (L-PBF) process. Two different post-heat-treatments including hot isostatic pressing and solution treatment are applied. The microstructure evaluation, potentiodynamic polarization, and electrochemical impedance spectroscopy methods are used to characterize L-PBF processed and post- treated specimens. Though as-built part exhibits anisotropic microstructure containing acicular α′ martensite with trace amount of β phase, the heat-treated parts are composed of α+β in which length and thickness of the α-lath depends on the treatment. The below β transus heat treatment leads to the formation of a homogenized grain structures composed of α+β. Electrochemical results show that the below β transus heat-treatment had a slight positive effect on the improvement of corrosion resistivity (corrosion rate of 4.2×10-6 mmy- 1 , which is classified as an excellent ) compared to other conditions, which would be associated to the natural excellent corrosion resistance of Ti-6Al-4V alloy. This slight improvement can be ascribed by the slightly faster formation of a passive layer and its enhanced efficiency because of the presence of the fine-structured β phase in post heat- treated L-PBF processed Ti-6Al-4V alloy. Show less

Type

Thesis

File type

application/pdf

Subject

Materials Science
additive manufacturing
Annealing treatment
corrosion
Hydride-dehydride powder
laser powder bed fusion
Saline water

Access

Restricted Access

Rights

In Copyright
http://rightsstatements.org/page/InC/1.0/

Identifier

http://hdl.handle.net/10560/islandora:1024836

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