Mechanical Engineering Commons^™

Increased Ductility Of Ti-6al-4v By Interlayer Milling During Directed Energy Deposition, Rakeshkumar Karunakaran, Luz D. Sotelo, Hitarth Maharaja, Calsey Nez, Monsuru Ramoni, Scott Halliday, Sushil Mishra, Joseph A. Turner, Michael P. Sealy

Department of Mechanical and Materials Engineering: Faculty Publications

Additive manufacturing (AM) often results in high strength but poor ductility in titanium alloys. Hybrid AM is a solution capable of improving both ductility and strength. In this study, hybrid AM of Ti-6Al-4V was achieved by coupling directed energy deposition with interlayer machining. The microstructure, residual stress, and microhardness were examined to explain how interlayer machining caused a 63% improvement in ductility while retaining an equivalent strength to as-printed samples. Interlayer machining introduced recurrent interruptions in printing that allowed for slow cooling-induced coarsening of acicular α laths at the machined interfaces. The coarse α laths on the selectively machined layers …

Integrating Temperature Dependence Into A Microstructure-Sensitive Fatigue Model For Titanium Alloys, Jared Michael Darius

Masters Theses

This work seeks to integrate temperature dependence into a microstructure-sensitive fatigue model for titanium alloys produced by both extrusion and electron beam melting (EBM) additive manufacturing, revising and enhancing the MultiStage Fatigue (MSF) model as the foundational model framework. Traditional fatigue modeling has required design engineers to conservatively use a lower-bound estimate of fatigue life predictions given a statistically significant spread of experimental data that can span up to two or sometimes three orders of magnitude for a given test condition. This variation in fatigue data has since been accounted for with the advent of the MSF model, linking individual …

Biofilm And Cell Adhesion Strength On Dental Implant Surfaces Via The Laser Spallation Technique, James D. Boyd, Arnold J. Stromberg, Craig S. Miller, Martha E. Grady

Statistics Faculty Publications

OBJECTIVE: The aims of this study are to quantify the adhesion strength differential between an oral bacterial biofilm and an osteoblast-like cell monolayer to a dental implant-simulant surface and develop a metric that quantifies the biocompatible effect of implant surfaces on bacterial and cell adhesion.

METHODS: High-amplitude short-duration stress waves generated by laser pulse absorption are used to spall bacteria and cells from titanium substrates. By carefully controlling laser fluence and calibration of laser fluence with applied stress, the adhesion difference between Streptococcus mutans biofilms and MG 63 osteoblast-like cell monolayers on smooth and rough titanium substrates is obtained. The …

Modeling And Optimization Of Process Parameters In Face Milling Of Ti6al4v Alloy Using Taguchi And Grey Relational Analysis, Al Mazedur Rahman, S M Abdur Rob, Anil K. Srivastava

Manufacturing & Industrial Engineering Faculty Publications and Presentations

Titanium alloys are extensively used in aerospace, missiles, rockets, naval ships, automotive, medical devices, and even the consumer electronics industry where a high strength to density ratio, lightweight, high corrosion resistance, and resistance to high temperatures are important. The machining of these alloys has always been challenging for manufacturers. This article investigates the combined effect of radial depth, cutting speed and feed rate on cutting forces, tool life, and surface roughness during face milling of Ti6Al4V alloy. This study focuses on the significance of radial depth of cut on cutting force, tool life and surface roughness compared to that of …

Building Zr-Based Metallic Glass Part On Ti-6al-4v Substrate By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Through using Zr intermediate layers, Zr_52.5Ti₅Al₁₀Ni_14.6Cu_17.9 metallic glass (MG) parts are successfully built on Ti-6Al-4V substrates by laser-foil-printing (LFP) additive manufacturing technology in which MG foils are laser welded layer-by-layer onto the substrate. The printed MG part is free of porosity, cracking and crystallization; additionally, its glass transition temperature, crystallization temperature, micro-hardness, and tensile strength are very similar to the original MG material. The Zr intermediate layers are aimed at preventing direct interaction between the first layer of MG foil and the Ti substrate; otherwise, the welded MG foils would peel …

Wire Electro-Discharge Machining Of Titanium Alloy, Farnaz Nourbakhsh, Kamlakar P. Rajurkar, Ajay P. Malshe, Jian Cao

Department of Mechanical and Materials Engineering: Faculty Publications

This paper presents an experimental investigation of wire electro-discharge machining (WEDM) of titanium alloy. The objective is to investigate the effect of seven process parameters including pulse width, servo reference voltage, pulse current, and wire tension on process performance parameters (such as cutting speed, wire rupture and surface integrity). A Taguchi L18 design of experiment (DOE) has been applied. All experiments have been conducted using Charmilles WEDM. It was also found that the cutting speed increases with peak current and pulse interval. Surface roughness was found to increase with pulse width and decrease with pulse interval. The Analysis of Variance …