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Aashish Rohatgi

Aashish Rohatgi

Pacific Northwest National Laboratory
PO Box 999
Richland, WA 99352
(509) 372-6047

Biography

Aashish Rohatgi has been with PNNL-Richland since 2008. He combines the core expertise in metallurgy/materials science with innovative ideas to achieve excellence in project execution. Dr. Rohatgi is the PI on multiple projects and he leads multi-disciplinary teams of scientists and engineers to solve lightweighting challenges for the automotive industry. Examples of his recent projects include warm-forming of Mg, corrosion mitigation in Mg-similar/dissimilar joints, high-rate forming of Al and steel, polymeric foams with metal-foam like performance, etc. He is also leading an integrated modeling and experimental project on the design and development of thermally stable nanostructured Al- and Mg-based alloys. Dr. Rohatgi is an expert in materials processing, physical metallurgy, and fundamental aspects of deformation behavior of materials, focusing on microstructure-property-processing correlations. He is experienced in the use of Hopkinson bars, load frames for quasi-static and medium-rate tests, digital image correlation (DIC), and variety of analytical techniques (SEM, TEM, EBSD, DSC etc.). He was previously with the U.S. Naval Research Laboratory, DC, where he led research on the development of multi-functional composites for the navy. Dr. Rohatgi has co-authored over 30 publications. He serves as the materials expert on the H2-delivery “Tech-Team” for the DOE-Fuel Cell Technology Office and serves on the editorial board of Metallurgical Transactions A as a Key Reader.

Research Interests

  • Light-weight materials R&D (processing, characterization, alloy development)
  • Design and fabrication of thermally stable nano-structured materials
  • High-strain-rate deformation in materials (impact, ballistics and blast)
  • Multifunctional and hierarchically structured materials
  • Liquid crystalline polymers and polymer composites
  • Bio-materials, bio-inspired and bio-mimetic materials

Education and Credentials

  • Ph.D. Materials Science & Eng., University of California San Diego, 1999
  • M.Eng. Metallurgical Engineering, McGill University, Canada, 1993
  • B.Eng. Metallurgical Engineering, University of Roorkee, India, 1990.

Affiliations and Professional Service

  • Member of TMS
  • Reviewer for Metallurgical Transactions A, Materials Science & Engineering, ASME Journal of Engineering Materials and Technology, Journal of Composite Materials, etc.

PNNL Patents

PNNL Publications

2023

  • Nasim W., T. Mungole, M. Efe, and A. Rohatgi. 2023. "Simultaneous Improvement in Strength and Ductility in 7xxx Al Through a Combination of Natural Aging and Deformation." Materials Science and Engineering A. Structural Materials: Properties, Microstructure and Processing 884. PNNL-SA-184861. doi:10.1016/j.msea.2023.145566
  • Rader K.E., A. Sabau, and A. Rohatgi. 2023. "Microstructural Refinement in Ultrasonically Modified A356 Aluminum Castings." Journal of Materials Science 58, no. 2023:17340-17361. PNNL-SA-186579. doi:10.1007/s10853-023-08999-y
  • Rader K.E., J.T. Darsell, J.L. Helgeland, N.L. Canfield, T.J. Roosendaal, E.K. Nickerson, and A.C. Denny, et al. 2023. "Improving the Mechanical Properties of Cast Aluminum Via Ultrasonication-Induced Microstructural Refinement." In Light Metals 2023: TMS Annual Meeting & Exhibition, edited by S. Broek, 422-428. PNNL-SA-177512. doi:10.1007/978-3-031-22532-1_57
  • Rohatgi A., S. Jana, and B. Kokosza. 2023. Mitigating Corrosion in Mg Sheet in Conjunction with a Sheet-Joining Method that Satisfies Structural Requirements within Sub-assemblies: CRADA 392. PNNL-35364. Richland, WA: Pacific Northwest National Laboratory. Mitigating Corrosion in Mg Sheet in Conjunction with a Sheet-Joining Method that Satisfies Structural Requirements within Sub-assemblies: CRADA 392

2022

  • Gwalani B., Q. Pang, A. Yu, W. Fu, L. Li, M. Pole, and C.J. Roach, et al. 2022. "Extended Shear Deformation of the Immiscible Cu-Nb Alloy Resulting in Nanostructuring and Oxygen Ingress with Enhancement in Mechanical Properties." ACS Omega 7, no. 16:13721-13736. PNNL-SA-169151. doi:10.1021/acsomega.1c07368
  • Li S., N. Chen, A. Rohatgi, Y. Li, C.A. Powell, S.N. Mathaudhu, and A. Devaraj, et al. 2022. "Nanotwin Assisted Reversible Formation of Low Angle Grain Boundary Upon Reciprocating Shear Load." Acta Materialia 230. PNNL-SA-167698. doi:10.1016/j.actamat.2022.117850
  • Ma X., B. Gwalani, J. Tao, M. Efe, M.J. Olszta, M. Song, and S.B. Yadav, et al. 2022. "Shear strain gradient in Cu/Nb nanolaminates: strain accommodation and chemical mixing." Acta Materialia 234. PNNL-SA-168943. doi:10.1016/j.actamat.2022.117986
  • Nasim W., H. Das, S.S. Kulkarni, A. Rohatgi, D.R. Herling, G.J. Grant, and P. Upadhyay, et al. 2022. "Local Thermomechanical Processing for Improving Formability of High Strength Aluminum Sheets." In SAE Annual World Congress Experience, (WCX 2022), April 5-7, 2022, Virtual, Online. SAE Technical Papers, Paper No. 2022-01-0244. Warrendale, Pennsylvania:SAE International. PNNL-SA-168320. doi:10.4271/2022-01-0244
  • Rohatgi A., and S. Hu. 2022. Effect of Processing on Precipitation Kinetics in Nano Polycrystalline 7075 Aluminum Alloy - CRADA 564. PNNL-32878. Richland, WA: Pacific Northwest National Laboratory. Effect of Processing on Precipitation Kinetics in Nano Polycrystalline 7075 Aluminum Alloy - CRADA 564

2021

  • Efe M., B. Gwalani, J. Tao, M. Song, T.C. Kaspar, A. Devaraj, and A. Rohatgi. 2021. "Nanomechanical Scratching Induced Local Shear Deformation and Microstructural Evolution in Single Crystalline Copper." Applied Surface Science 562. PNNL-SA-158843. doi:10.1016/j.apsusc.2021.150132
  • Efe M., T. Mungole, D. Weiss, and A. Rohatgi. 2021. Overcoming the Barriers to Lightweighting by Enabling Low-Cost and High-Performance Structural Automotive Aluminum Castings (CRADA 404). PNNL-35668. Richland, WA: Pacific Northwest National Laboratory. Overcoming the Barriers to Lightweighting by Enabling Low-Cost and High-Performance Structural Automotive Aluminum Castings (CRADA 404)
  • Gwalani B., W. Fu, M.J. Olszta, J.A. Silverstein, D. Yadav, P. Manimunda, and A.D. Guzman, et al. 2021. "Lattice misorientation evolution and grain refinement in Al-Si alloys under high-strain shear deformation." Materialia 18. PNNL-SA-160821. doi:10.1016/j.mtla.2021.101146
  • Jana S., M.J. Olszta, D.J. Edwards, M.H. Engelhard, A. Samanta, H. Ding, and P. Murkute, et al. 2021. "Microstructural basis for improved corrosion resistance of laser surface processed AZ31 Mg alloy." Corrosion Science 191. PNNL-SA-156519. doi:10.1016/j.corsci.2021.109707
  • Kaspar T.C., Q. Pang, P.V. Sushko, M.E. Bowden, J. Tao, B. Gwalani, and M.J. Olszta, et al. 2021. "Metastable orientation relationships in thin film Cu-Cr bilayers." Scripta Materialia 194. PNNL-SA-156813. doi:10.1016/j.scriptamat.2020.113635
  • Rohatgi A., K. Sadayappan, D.T. Clelland, and G. Birsan. 2021. "Joining Light Metals with Polymer Composites Through Metal Overcasting." Journal of Materials Processing Technology 298. PNNL-SA-158758. doi:10.1016/j.jmatprotec.2021.117257

2020

  • Gwalani B., M.J. Olszta, S. Varma, L. Li, A. Soulami, E.J. Kautz, and S. Pathak, et al. 2020. "Extreme Shear-Deformation-Induced Modification of Defect Structures and Hierarchical Microstructure in an Al-Si Alloy." Communications Materials 1. PNNL-SA-153669. doi:10.1038/s43246-020-00087-x

2019

  • Devaraj A., W. Wang, V.R. Vemuri, L. Kovarik, X. Jiang, M.E. Bowden, and J.R. Trelewicz, et al. 2019. "Grain Boundary Segregation and Intermetallic Precipitation in Coarsening Resistant Nanocrystalline Aluminum Alloys." Acta Materialia 165. PNNL-SA-135423. doi:10.1016/j.actamat.2018.09.038

2017

  • Kruska K., A. Rohatgi, V.S. Vemuri, L. Kovarik, T.H. Moser, J.E. Evans, and N.D. Browning. 2017. "Grain growth in nanocrystalline Mg-Al thin films." Metallurgical and Materials Transactions A - Physical Metallurgy and Materials Science 48A, no. 12:6118-6125. PNNL-SA-113636. doi:10.1007/s11661-017-4350-0
  • Nandipati G., X. Jiang, V.S. Vemuri, S. Mathaudhu, and A. Rohatgi. 2017. "Self-Learning Kinetic Monte Carlo Simulations of Diffusion in Ferromagnetic a-Fe-Si alloys." Journal of Physics: Condensed Matter 30, no. 3:Article No. 035903. PNNL-SA-124267. doi:10.1088/1361-648X/aa9774

2016

  • Nandipati G., N. Govind, A. Andersen, and A. Rohatgi. 2016. "Self-Learning Kinetic Monte Carlo Simulations of Al Diffusion in Mg." Journal of Physics: Condensed Matter 28, no. 15:Article No. 155001. PNNL-SA-111640. doi:10.1088/0953-8984/28/15/155001
  • Prabhakaran R., J. Choi, E.V. Stephens, D. Catalini, C.A. Lavender, and A. Rohatgi. 2016. "Mechanical Characterization and Corrosion Testing of X608 Al Alloy." In Light Metals 2016, edited by E. Williams. 145-150. Hoboken, New Jersey:John Wiley & Sons, Inc. PNNL-SA-113866.

2015

  • Choi J., A. Rohatgi, M.T. Smith, and C.A. Lavender. 2015. "Process Development for Stamping -Pillar Covers with Aluminum." In Light Metals 2015: Proceedings of the symposia sponsored by the TMS Aluminum Committee at the TMS 2015 Annual Meeting & Exhibition, March 15-19, 2015, Orlando, Florida, edited by M Hyland, 197-202. Hoboken, New Jersey:John Wiley and Sons, Inc. PNNL-SA-105374. doi:10.1002/9781119093435.ch35
  • Upadhyay P., A. Rohatgi, E.V. Stephens, R.W. Davies, and D. Catalini. 2015. "HIGH-RATE FORMABILITY OF HIGH-STRENGTH ALUMINUM ALLOYS: A STUDY ON OBJECTIVITY OF MEASURED STRAIN AND STRAIN RATE." In Light Metals 2015: Proceedings of the symposia sponsored by the TMS Aluminum Committee at the TMS 2015 Annual Meeting & Exhibition, March 15-19, 2015, Orlando, Florida, edited by M Hyland, 327-332. Hoboken, New Jersey:John Wiley & Sons, Inc. PNNL-SA-105367. doi:10.1002/9781119093435.ch55

2014

  • Rohatgi A., A. Soulami, E.V. Stephens, R.W. Davies, and M.T. Smith. 2014. "An Investigation of Enhanced Formability in AA5182-O Al During High-Rate Fre-Forming at Room-Temperature: Quantification of Deformation History." Journal of Materials Processing Technology 214, no. 3:722-732. PNNL-SA-87055. doi:10.1016/j.jmatprotec.2013.07.015
  • Rohatgi A., R.W. Davies, E.V. Stephens, A. Soulami, and M.T. Smith. 2014. "An Experimental and Modeling Investigation on High-Rate Formability of Aluminum." In Light Metals 2014, February 16-20, 2014, San Diego, California, edited by J Grandfield, 219-225. Hoboken, New Jersey:John Wiley & Sons. PNNL-SA-98651. doi:10.1002/9781118888438.ch38
  • Zhang K., X.S. Li, W. Li, A. Rohatgi, Y. Duan, P. Singh, and L. Li, et al. 2014. "Phase Transfer-Catalyzed Fast CO2 Absorption by MgO-Based Absorbents with High Cycling Capacity." Advanced Materials Interfaces 1, no. 3:Article No. 1400030. PNNL-SA-98809. doi:10.1002/admi.201400030

2013

  • Crum J.V., D.M. Strachan, A. Rohatgi, and M.R. Zumhoff. 2013. "Epsilon Metal Waste Form for Immobilization of Noble Metals from Used Nuclear Fuel." Journal of Nuclear Materials 441, no. 1-3:103-112. PNNL-SA-100524. doi:10.1016/j.jnucmat.2013.05.043
  • Rohatgi A., and K.I. Johnson. 2013. "Investigation of H2 Diaphragm Compressors to Enable Low-Cost Long-Life Operation." In FY 2013 Progress Report for the DOE Hydrogen and Fuel Cells Program. III-53 - III-55. Oak Ridge, Tennessee:US Department of Energy. PNNL-22718.
  • Rohatgi A., E.V. Stephens, R.W. Davies, and M.T. Smith. 2013. "AN INVESTIGATION OF SHEET METAL DEFORMATION BEHAVIOR DURING ELECTRO-HYDRAULIC FORMING (EHF)." In ASME 2013 Manufacturing Science and Engineering Conference (MSEC 2013), June 10-14, 2013, Madison, Wisconsin, 1, V001T01A011 Paper No. MSEC2013-1129. New York, New York:ASME. PNNL-SA-92085. doi:10.1115/MSEC2013-1129
  • Williams J.J., J. Walters, M. Wang, N. Chawla, and A. Rohatgi. 2013. "Extracting Constitutive Stress-Strain Behavior of Microscopic Phases by Micropillar Compression." JOM. The Journal of the Minerals, Metals and Materials Society 65, no. 2:226-233. PNNL-SA-90972. doi:10.1007/s11837-012-0516-9

2012

  • Rohatgi A., E.V. Stephens, D.J. Edwards, M.T. Smith, and R.W. Davies. 2012. "Electro-hydraulic forming of advanced high-strength steels: Deformation and microstructural characterization." In ASME Manufacturing Science and Engineering Conference (MSEC2012), June 4-8, 2012, Notre Dame, Indiana, 163-168. New York, New York:ASME. PNNL-SA-84265. doi:10.1115/MSEC2012-7322
  • Rohatgi A., E.V. Stephens, R.W. Davies, M.T. Smith, A. Soulami, and S. Ahzi. 2012. "Electro-Hydraulic Forming of Sheet Metals: Free-forming vs. Conical-die Forming." Journal of Materials Processing Technology 212, no. 5:1070-1079. PNNL-SA-82938. doi:10.1016/j.jmatprotec.2011.12.014

2011

  • Rohatgi A., E.V. Stephens, A. Soulami, R.W. Davies, and M.T. Smith. 2011. "Experimental Characterization of Sheet Metal Deformation During Electro-Hydraulic Forming." Journal of Materials Processing Technology 211, no. 11:1824-1833. PNNL-SA-78155. doi:10.1016/j.jmatprotec.2011.06.005

2010

  • Rohatgi A., E.V. Stephens, A. Soulami, R.W. Davies, and M.T. Smith. 2010. "High-Strain-Rate Forming of Aluminum and Steel Sheets for Automotive Applications." In Proceedings of the International Deep Drawing Group Conference (IDDRG-2010 ), May 31-June 02, 2010, Graz, Austria. Brussels:International Deep Drawing Research Group. PNNL-SA-71641.

2009

  • Rohatgi A., D.R. Herling, and E.A. Nyberg. 2009. "CHARACTERIZATION AND FORMABILITY OF CONTINUOUS-CAST AZ31B MAGNESIUM ALLOY SHEETS." In Magnesium Technology 2010, edited by SR Agnew, NR Neelameggham, EA Nyberg and WH Sillekens, 573-578. Warrendale, Pennsylvania:TMS. PNNL-SA-68612.

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