2013-2014

TMS 2014 143rd Annual Meeting & Exhibition

TMS 143rd Annual Meeting & Exhibition was held on February 16-20,2014 in San Diego Cnvention Center in San Diego.

143rd Annual Meeting & Exhibition
February 16-20, 2014
San Diego Convention Center
San Diego, California USA

Our Members Who Attended

Professors

Diran Apelian, Diana Lados and Yiming Rong.

Graduate Students

Luke Bassett, Dr. Danielle Belsito, Aaron Birt, Xiang Chen, Chen Dai, Dr. Antastasios Gavras, Shaymus Hudson, Theodoros Koutsoukis, Baillie McNally, Yi Pan, Hayley Sandgren, Dr. Sumanth Shankar, Anthony Spangenberger, Dr. Chang-Kai Wu, Yang Yang, Yuwei Zhai

Presentations 

Through-Process Modeling of Al Alloy Optimization for Cold Spray Processing

Danielle Belsito, Baillie McNally, Victor Champagne, Richard D. Sisson, Jr.

Worcester Polytechnic Institute, U.S. Army Research Laboratory

Military aircraft that require high maneuverability, durability, ballistic protection, reparability, and energy efficiency need structural alloys with low density, high toughness, and high strength. The primary focus of this effort is to develop a nano-structured alloy powder that can be consolidated by the cold spray process to meet these materials requirements. Through-process modeling will be utilized as a predictive tool to design optimum materials and processing parameters for the cold spray process. The four stages in the through-process model are powder production, powder preparation, cold spray processing, and post-processing.  This paper will focus on the first two stages, using computational thermodynamic and kinetic models to aid in the novel material design.  Also, microstructure and microchemistry development during powder production and preparation as well as deformation and microstructure changes during the cold spay process will be discussed.

Microstructural Characterization and Analysis of Cold Spray Al Alloys

Baillie McNally, Danielle Belsito, Luke Bassett, Victor Champagne, Richard Sisson, Jr. 

The cold spray process is a cost effective process for repairing damaged parts or creating structural bulk materials for military aircraft that require high maneuverability, durability, and energy efficiency. A tailored high strength, high toughness, light weight alloy is needed for this application that would optimize the properties of the deposited materials. A through-process model would benefit this process significantly. The first two stages, the powder production and preparation models, can identify the optimum microstructure and microchemistry of the material. The particle impact model predicts the deformation of powder particles during the cold spray process. Current work focuses on the experimental characterization that verifies and enhances our thermodynamic, solidification, kinetic, and particle impact modeling. Particle, grain size and microstructural morphology for powders and corresponding cold sprayed materials are determined through optical and scanning electron microscopy. X-ray diffraction along with scanning and transmission electron microscopy are used to identify the phases present and precipitate morphology. Finally, mechanical property testing will be correlated to the amount of deformation predicted by the particle impact model.

Simulating Particle Impact to Predict the Mechanical Properties of Cold Sprayed Alloys

Luke Bassett, Danielle Belsito, Baillie McNally, Richard Sisson Jr.,Victor Champagne, Diran Apelian

Cold spray deposition is a rapidly developing material consolidation process in which powder particles are accelerated by a high velocity gas stream onto a substrate with sufficient energy to induce bonding.  The consolidated structure often has high strength and hardness when compared to a similar wrought alloy. Although predictive modeling has been carried out for various portions of the process, a detailed investigation of the particle and substrate deformation during impact and a comparison to the final microstructure and mechanical properties is needed.  The goal of this research is to model the cold spray process and to compare microstructure and property predictions to experimental results.  An ABAQUS/Explicit simulation of single and multiple particle impacts has been performed.  Efforts will be made to correlate impact and deformation phenomena to material properties.  Results will be presented and discussed.  

Effects of Hot Compressive Dwell on Fatigue Crack Growth Behavior of Cast Aluminum Alloys  

Xiang Chen, Diana A. Lados (Worcester Polytechnic Institute, Integrative Materials Design Center) Richard G. Pettit (FractureLab, LLC)

Fatigue crack growth under Hot Compressive Dwell (HCD) conditions is an important failure mode in many high temperature applications, such as cylinder heads used in internal combustion engines.  Tensile residual stresses gradually building up at the crack root are considered a key factor contributing to crack growth under HCD conditions.  To understand and quantify this effect, both at elevated and room temperatures, an analytical model was developed, in which the residual stress contributions are added to the elastic response of the material to predict the behavior under HCD conditions.  Cyclic stress relaxation tests were conducted to model tensile residual stress accumulation.  A Blunt Compact Tension (BCT) specimen was designed and analyzed using Franc2D to determine the elastic/plastic behavior.  Finally, crack growth tests on BCT specimens under HCD conditions were performed to validate the model.  These results will be presented and discussed for 319 cast aluminum alloys used in engine applications.

Friction Stir Processing and Weldingof Wrought and Cast Aluminum Alloys: Property Evaluations and Novel Applications

Yi Pan and Diana A. Lados

Worcester Polytechnic Institute, Integrative Materials Design Center

Friction stir welding and processing (FSW/FSP) aresolid-state techniqueswidely used for joining and repairing in the transportation sector, and understanding their effects on static and dynamic properties is critical for structural integrity.  In this study, four aluminum alloy systems (wrought 6061 and cast A356, 319, and A390) were friction stir processed using various processing parameters in both as-fabricated and pre-weld heat treated conditions.  The effects of processing and heat treatmenton the resulting microstructures, hardness/micro-hardness, and tensileand fatigue crack growth(FCG) properties were systematically investigated and mechanistically correlated.  Tensile and FCG testswere performed in room temperature air.  Optimum processing parameters domains that provide both defect-free welds and good mechanical propertieswere determinedfor each alloy and associated to the thermal history of the process.In addition, application of FSW/FSP to create novel metal matrix nano-composites was investigated.  The results of these studies will be presented and discussed.

Processing Considerations, Microstructures, and Properties of Ti-6Al-4V Fabricated by Laser Engineered Net Shaping

Yuwei Zhai, Hayley R. Sandgren, and Diana A. Lados

Laser Engineered Net Shaping (LENS) is one of the Additive Manufacturing (AM) technologies developed for rapid manufacturing of metallic materials.  Contrary to conventional processing routes, the LENS layer-by-layer build-ups result in different microstructures and properties due to the localized heat input and high cooling rates.  In this study, Ti-6Al-4V alloys were fabricated by LENS using two power levels (low and high), and were investigated in both as-fabricated and post-LENS heat treated conditions.  The effects of processing power and heat treatment on microstructure were extensively studied using optical and scanning electron microscopy.  Room temperature tensile properties were characterized in different orientations with respect to the deposition direction.  Long and small fatigue crack growth tests were conducted in room temperature air, and fatigue crack growth mechanisms at various stages were determined.  Static and dynamic properties, microstructures, and damage mechanisms were uniquely correlated, and the findings will be systematically presented and discussed.

Long and Small Fatigue Crack Growth in Aluminum Alloys

Anthony Spangenberger, Anastasios Gavras, Diana Lados

Fatigue crack growth (FCG) studies at various stress ratios (R=0.1, 0.5, 0.7) were performed on solution-strengthened (cast A535) and precipitation-strengthened (cast A356, 319, A390 and wrought 6061) aluminum alloys.  Microstructures were altered through processing, chemistry, and heat treatment (T4, T6, T7) to shed light on the effects of various intrinsic material characteristic features on FCG (e.g. Si amount/type/morphology, grain size, secondary dendrite arm spacing, precipitate type/size).  In this context, mechanisms of long and small fatigue crack growth at the microstructural scale of the studied alloys were identified, and loading-microstructure-damage mechanisms design maps were created.  The differences in FCG responses between long, physically-small, and microstructurally-small cracks were systematically evaluated, and an original fracture mechanics – materials science combined model that accounts for these differences was developed, having both material and crack size dependency.  Examples of the use of this integrated methodology for design and fatigue life predictions will also be given.

February 16, 2014