Faculty News

TMS 2011 140th Annual Meeting & Exhibition

Early Career Faculty Fellow Award presented to Prof. Diana Lados by TMS on March 1, 2011 at the 140th TMS Annual Meeting and Exhibition in San Diego, Carlifornia for her outstanding contribution in Metallurgy and Materials Science.

Early Career Faculty Fellow Award presented to Prof. Diana Lados by TMS on March 1, 2011 at the 140th TMS Annual Meeting and Exhibition in San Diego, Carlifornia for her outstanding contribution in Metallurgy and Materials Science.

The conference held in San Diego, California was attended by:

Professors:

Diran Apelian, Diana Lados, Makhlouf Makhlouf, Richard D. Sisson, Jr.

Graduate Students:

Andrew Biro, Xiang Chen, Anastasios Gavras, Chang-Kai Wu

Papers Presented:

Presentations Given:

Lectures Given:

Session Chaired :

Hume-Rothery Symposium thermodynamics and Diffusion Coupling in alloys - Application Driven Science: Materials Design and diffusional Simulations (Richard Sisson)

 

Integrative Materials-Process-Component Design: A Prospective View

Speaker: Prof. Diana Lados

Abstract

The challenges in modern materials-process-component design revolve around the successful integration of several important and sometimes competing concepts such as high-performance & reliability, societal impact, and economics. This generates a fertile future of opportunities for the clever materials engineer to develop a holistic approach based on a fundamental understanding in tandem with suitable and sustainable application-driven design and manufacturing strategies. These ideas will be systematically reviewed and discussed in the context of needs and developments, and exciting materials research opportunities will be presented.

The Pivotal Role of Materials Science and Engineering for an Energy Efficient and Low Carbon Economy

Speaker: Prof. Diran Apelian

Abstract:

The most critical issue we face as a global society for a sustainable 21st century on the planet earth is energy. During the last 10 years, world population increased by 1billion - from 6 billion to 7 billion in one decade. Annual projections for population growth hover a bit over 1.4% whereas energy consumption is growing at a faster rate ~1.7%; certainly not a sustainable scenario. Innovation in materials and material processing technologies is critical to achieving the longer term objectives of an energyefficient and low-carbon world. While significant efforts have been made to identify breakthrough materials and their benefits, less attention has been given to the integration with materials manufacturing, including synthesis science, needed to propel promising materials candidates across the “valley of death” into cost-effective application at scale. This presentation will provide an overview of a study commissioned by the U.S. Department of Energy focused on identifying those areas where materials science and engineering can have the most significant impacts on energy efficiency and carbon reduction.

Creep Fatigue Behavior of 319 Aluminium Casting Alloys Under Hot Compressive Dwell Conditions

Authors:

Xiang Chen, Diana A. Lados, Richard G. Pettit

Abstract:

Fatigue crack growth under Hot Compressive Dwell (HCD) conditions is an important failure mode for many high temperature applications, such as cylinder heads for internal combustion engines.  A new testing methodology was developed to study the creep mechanism that accelerates the growth of cracks loaded with a compressive dwell cycle.  Tensile residual stress build up at the crack root is considered a key factor contributing to crack growth under HCD conditions.  To evaluate this effect quantitatively, stress relaxation and crack growth tests were performed to determine the creep and crack growth responses of the material.  A Blunt Compact Tension (BCT) specimen was then analyzed using FRANC2D to determine the stress distribution, and obtain a 2D weight function K-solution.  The residual stress distribution is then applied via the weight function to determine residual K that builds up during the operating life of the part.  These results will be presented and discussed.

Investigation of the Fatigue Crack Growth Behavior of Wrought and Cast Light Metals

Authors: 

Anastasios G. Gavras, Brendan F. Chenelle, and Diana A. Lados

Abstract:

The response of light metals under fatigue crack growth conditions was investigated. Fatigue crack growth experiments were conducted on cast and wrought aluminum alloys (A535 and 6061), wrought titanium alloys (Ti-6Al-4V), and alloys processed by novel techniques (6061 aluminum alloys processed by cold spray and friction stir welding). Microstructural effects on the resistance to fatigue crack propagation within each class of materials were evaluated by altering the microstructure through heat treatment, chemistry, and processing. In addition, initial crack size effects were studied for each material under various stress ratios (R=0.1, R=0.5, and R=0.7). The mechanisms of fatigue crack growth at the microstructural scale were identified and will be discussed. The differences in the behavior and controlling crack growth mechanisms between long and small cracks, in the near-threshold regime, and their importance in design are also discussed. Recommendations for integrating materials knowledge into a new design approach for fatigue crack growth resistance are provided.

Modeling the Microstructural Development during the Nitriding of Low Alloy Steels

Authors:

Mei Yang, Danielle Belsito, Richard Sisson

Abstract:

The microstructural development during the nitriding of quenched and tempered low alloy steels has been theoretically and experimentally investigated.  These results will be compared with those of CALPHAD calculations from Thermo-Calc, which use thermodynamic data to predict multicomponent phase behavior during nitriding.  Isopleths with nitrogen content will be presented for steels with and without added aluminum.  Customized Lehrer diagrams will be developed to predict the relationship between the nitriding potential and the phase development at different temperatures.  In addition, a computational model is being developed to predict the nitriding behavior.  The methodology and preliminary results for this model will be presented and compared with experimental results.

Predicting the Response of Aluminum Casting Alloys to Heat Treatment

Authors:

Chang-Kai Wu, Prof. Makhlouf M. Makhlouf

Abstract:

In this publication we report on the development of a mathematical model that enables predicting the changes in hardness of cast aluminum alloy components in response to heat treatment. This model is part of a more inclusive model that is currently under development and that when completed, will enable predicting the changes in room temperature tensile properties as a function of heat treatment.

The model uses the commercially available finite element analysis software (ABAQUS) and an extensive database that was developed specifically for the aluminum alloy under consideration (namely, A356.2). The database includes mechanical, physical and thermal properties of the alloy all as functions of temperature. In addition, boundary conditions – in the form of the heat transfer coefficient associated with each one of the heat treatment steps – are obtained from measurements performed with specially designed quenching devices. The database and boundary conditions are used in a thermal analysis module and a user-developed module. The user-developed module uses Quench Factor Analysis to predict the maximum attainable hardness that develops in a commercial cast component that is subjected to a standard commercial heat treating cycle. A heat-treated part was used to validate the model prediction.

March 7, 2011