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Bauder, Tyler J.

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Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel./
Author:	Bauder, Tyler J.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2023,
Description:	250 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30636378
ISBN:	9798380325035

Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel.
Bauder, Tyler J.

Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 250 p.

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--Michigan State University, 2023.

This item must not be sold to any third party vendors.

Electron Beam Melting (EBM) is a relatively new Powder Bed Fusion (PBF) Additive Manufacturing (AM) process. Unlike a very similar laser PBF process, the EBM process occurs in an Ultra-High Vacuum (UHV) and high temperature (~700C) chamber, reducing residual stress and providing superior protection against oxidation. This makes EMB ideal for processing oxygen sensitive materials like Ti-6Al-4V, whose high strength-to-weight ratio, corrosion resistance, and high temperature performance have drawn the interest of aerospace and other high-performance manufacturing. Due to the nature of these industries, fatigue life is of particular interest. However, the relationship between EBM processing and fatigue life is not well studied and is thus the focus of this dissertation.First, a L16 Taguchi Design of Experiments (DOE) was constructed to investigate the effects of Focus Offset, Line Offset, Speed Function, Hot Isostatic Pressing (HIP) treatment, and surface roughness on the Very High Cycle (VHC) fatigue life of Ti-6Al-4V. Two HIP treatments were 800°C and 200 MPa for 2 hours and 1100°C and 100 MPa for 2 hours with 2.5°C/min quench. Half of the samples were tested in the as-machined condition with an average roughness, Ra, of 0.2 μm and the other half were further polished using Magnetic Assisted Finishing (MAF) to Ra = 0.1 μm. An ultrasonic fatigue testing machine was used to test fatigue life at 500 and 550 MPa loads, with a load ratio of R = -1. Nearly 225 samples were tested with 7 repeats per load condition.Fatigue results indicated that none of the machine parameters and surface roughness had a statistically significant correlation with fatigue life. However, a statistically significant correlation between HIP treatment and fatigue life was found. The 800°C samples performed as well as, if not superior, to conventional Ti64 with the average fatigue lives of 8.08E+07 and 3.28E+06 cycles for 500 and 550 MPa, respectively. In contrast, the 1100°C samples had significantly lower fatigue performance with the average fatigue lives of 7.21E+05 and 1.38E+05 cycles for 500 and 550 MPa, respectively. Microstructure and fractography investigations suggest that the poor performance of 1100°C samples can be attributed to coarsening of the prior beta (β) grains during the super-transus HIP treatment leading to the formation of large colonies of similarly orientated alpha (α) grains, allowing for easier dislocation movement across aligned preferential slip directions.This study concluded that the most important factor controlling fatigue life of EBMed Ti-6Al-4V is post HIP/heat treatment and that fine-tuning of print settings beyond those required to prevent obvious porosity and swelling defects will not have significant effects on the fatigue life of HIPed Ti-6Al-4V.

ISBN: 9798380325035Subjects--Topical Terms:

586835
Engineering.
Subjects--Index Terms:

Additive manufacturing

Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel.
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245 1 0 $a Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2023
300 $a 250 p.
500 $a Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
500 $a Advisor: Kwon, Patrick.
502 $a Thesis (Ph.D.)--Michigan State University, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a Electron Beam Melting (EBM) is a relatively new Powder Bed Fusion (PBF) Additive Manufacturing (AM) process. Unlike a very similar laser PBF process, the EBM process occurs in an Ultra-High Vacuum (UHV) and high temperature (~700C) chamber, reducing residual stress and providing superior protection against oxidation. This makes EMB ideal for processing oxygen sensitive materials like Ti-6Al-4V, whose high strength-to-weight ratio, corrosion resistance, and high temperature performance have drawn the interest of aerospace and other high-performance manufacturing. Due to the nature of these industries, fatigue life is of particular interest. However, the relationship between EBM processing and fatigue life is not well studied and is thus the focus of this dissertation.First, a L16 Taguchi Design of Experiments (DOE) was constructed to investigate the effects of Focus Offset, Line Offset, Speed Function, Hot Isostatic Pressing (HIP) treatment, and surface roughness on the Very High Cycle (VHC) fatigue life of Ti-6Al-4V. Two HIP treatments were 800°C and 200 MPa for 2 hours and 1100°C and 100 MPa for 2 hours with 2.5°C/min quench. Half of the samples were tested in the as-machined condition with an average roughness, Ra, of 0.2 μm and the other half were further polished using Magnetic Assisted Finishing (MAF) to Ra = 0.1 μm. An ultrasonic fatigue testing machine was used to test fatigue life at 500 and 550 MPa loads, with a load ratio of R = -1. Nearly 225 samples were tested with 7 repeats per load condition.Fatigue results indicated that none of the machine parameters and surface roughness had a statistically significant correlation with fatigue life. However, a statistically significant correlation between HIP treatment and fatigue life was found. The 800°C samples performed as well as, if not superior, to conventional Ti64 with the average fatigue lives of 8.08E+07 and 3.28E+06 cycles for 500 and 550 MPa, respectively. In contrast, the 1100°C samples had significantly lower fatigue performance with the average fatigue lives of 7.21E+05 and 1.38E+05 cycles for 500 and 550 MPa, respectively. Microstructure and fractography investigations suggest that the poor performance of 1100°C samples can be attributed to coarsening of the prior beta (β) grains during the super-transus HIP treatment leading to the formation of large colonies of similarly orientated alpha (α) grains, allowing for easier dislocation movement across aligned preferential slip directions.This study concluded that the most important factor controlling fatigue life of EBMed Ti-6Al-4V is post HIP/heat treatment and that fine-tuning of print settings beyond those required to prevent obvious porosity and swelling defects will not have significant effects on the fatigue life of HIPed Ti-6Al-4V.
590 $a School code: 0128.
650 4 $a Engineering. $3 586835
650 4 $a High temperature physics. $3 3192580
650 4 $a Mechanical engineering. $3 649730
653 $a Additive manufacturing
653 $a Electron beam melting
653 $a Parameter optimization
653 $a Very high cycle fatigue
690 $a 0537
690 $a 0597
690 $a 0548
710 2 $a Michigan State University. $b Mechanical Engineering - Doctor of Philosophy. $3 2106417
773 0 $t Dissertations Abstracts International $g 85-03B.
790 $a 0128
791 $a Ph.D.
792 $a 2023
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30636378