A5067519014- Microstructure and Mechanical Properties of Steels
- Metal Alloys Wear and Properties
- High Temperature Alloys and Creep
- Hydrogen embrittlement and corrosion behaviors in metals
- Metallurgy and Material Forming
- Advanced Materials Characterization Techniques
- Advanced Welding Techniques Analysis
- Additive Manufacturing Materials and Processes
- High Entropy Alloys Studies
- Intermetallics and Advanced Alloy Properties
- Magnetic properties of thin films
- Microstructure and mechanical properties
- Metal and Thin Film Mechanics
- Heat transfer and supercritical fluids
- Advanced materials and composites
- Advanced Combustion Engine Technologies
- Aluminum Alloy Microstructure Properties
- Magnetic Properties and Applications
- Social Work Education and Practice
- Material Properties and Applications
- Materials Engineering and Processing
- Aluminum Alloys Composites Properties
- Advanced Electron Microscopy Techniques and Applications
- Fusion materials and technologies
- Surface and Thin Film Phenomena
Oak Ridge National Laboratory
2016-2025
Colorado School of Mines
2014-2020
Vanderbilt University
2012-2015
Center for Nanoscale Science and Technology
2013
National Institute of Standards and Technology
1986-2013
Vanderbilt Health
2012
University of Nevada, Reno
1999
We report local probe investigations of the magnetic interaction between BiFeO${}_{3}$ films and a ferromagnetic Co${}_{0.9}$Fe${}_{0.1}$ layer. Within constraints intralayer exchange coupling in Co${}_{0.9}$Fe${}_{0.1}$, multiferroic imprint ferromagnet results collinear arrangement magnetization in-plane ferroelectric polarization. The anisotropy is uniaxial, an effective field order 10 mT derived. Measurements as function layer thickness show that influence on becomes negligible for 3 nm...
Here we present results on the fabrication of steel-aluminum bi-metallic structures using directed energy deposition additive manufacturing. The challenges associated with a sharp transition from steel to aluminum are uncovered ex-situ characterization techniques and thermo-mechanical modeling process. It was found that is challenging extensive cracking observed at interface. attributed combined effect residual stress development due thermal expansion coefficient mismatch presence ordered...
Steels are ubiquitous due to their affordability and the landscape of useful properties that can be generated for engineering applications. But further expand performance envelope, one must able understand control microstructure development by alloying processing. Here we use multiscale, advanced characterization better structural chemical evolution AISI 4340 steel after quenching tempering (Q&T), including role quench rate short-time, isothermal below 573 K (300 °C), with an emphasis on...
In this work, dissimilar rotary inertia friction welds between 422 martensitic stainless steel and 4140 low-alloy were made to fabricate prototype heavy-duty diesel engine pistons. The influence of the welding process post weld heat treatment (PWHT) temperature on interfacial microstructure evolutions corresponding effects mechanical properties 422/4140 evaluated in detail. Carbon diffused from side during PWHT at 650 °C for 1.5 hours, causing formation a hard carbide-rich layer side, softer...
In this study, a sharp transition from 316L stainless steel to 4043 aluminum alloy was fabricated using wire directed energy deposition (DED) via the cold metal transfer (CMT) process. The CMT process with its inherently low heat input, led significant reduction in intermetallic thickness at bi-material interface compared blown powder DED technique resulting superior properties when literature reported values for dissimilar steel-aluminum welds. Thermo-kinetic modeling confirmed that...
AISI 422 martensitic stainless steel with superior hightemperature performance (oxidation resistance and strength) is under evaluation for replacing current heavy-duty piston crown materials, 4140 microalloyed (MAS) 38MnSiVS5, to fabricate a multimaterial (Refs. 1, 2). This concept further improved power density fuel economy by allowing heavyduty diesel engines operate at higher temperatures pressures (Ref. 3). Joining crowns skirts key manufacturing step this piston. However, the...
Abstract High temperature ferritic-martensitic steels are candidate materials for heavy-duty diesel engine pistons. The envisioned transition to hydrogen blended fuels is expected alter the post-combustion atmosphere in engines, primarily resulting a higher water vapor content (> 20 vol%) and potentially exhaust gas temperatures. oxidation resistance of existing newly developed alloys will be critical life-limiting mechanism under these conditions. In present work, behavior piston was...
The thermal and mechanical properties of martensitic stainless steel 422 were evaluated for suitability as a drop-in replacement 4140 in next generation heavy-duty diesel engine (HDDE) pistons. time temperature the austenitization tempering steps studied to achieve optimum materials performance piston applications, including balance resistance long-term aging. Reducing from 700 600 °C caused substantial increase elevated strength 25 °C, but had no significant influence on conductivity,...
<div class="section abstract"><div class="htmlview paragraph">Five different commercially available high-temperature martensitic steels were evaluated for use in a heavy-duty diesel engine piston application and compared to existing alloys 4140 microalloyed steel 38MnSiVS5 (MAS). Finite element analyses (FEA) performed predict the temperature stress distributions severe operating conditions of interest, thus aid selection candidate steels. Complementary material testing was...