國立虎尾科技大學 |

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:	Language materials, manuscript : 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.
Description:	1 online resource (250 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
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. - 1 online resource (250 pages)

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

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

Includes bibliographical references

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.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380325035Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Additive manufacturingIndex Terms--Genre/Form:

554714
Electronic books.

Efforts to Link Machine Parameters to Very High Cycle Fatigue Life of Electron Beam Melted Ti-6Al-4V and SEAM Produced 4340 Steel.
LDR:04237ntm a2200385K 4500 001 1141616
005 20240318062655.5
006 m o d
007 cr mn ---uuuuu
008 250605s2023 xx obm 000 0 eng d
020 $a 9798380325035
035 $a (MiAaPQ)AAI30636378
035 $a AAI30636378
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Bauder, Tyler J. $3 1465513
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.
264 0 $c 2023
300 $a 1 online resource (250 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
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.
504 $a Includes bibliographical references
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.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
650 4 $a High temperature physics. $3 1148654
650 4 $a Engineering. $3 561152
653 $a Additive manufacturing
653 $a Electron beam melting
653 $a Parameter optimization
653 $a Very high cycle fatigue
655 7 $a Electronic books. $2 local $3 554714
690 $a 0537
690 $a 0597
690 $a 0548
710 2 $a Michigan State University. $b Mechanical Engineering - Doctor of Philosophy. $3 1148515
710 2 $a ProQuest Information and Learning Co. $3 1178819
773 0 $t Dissertations Abstracts International $g 85-03B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30636378 $z click for full text (PQDT)