@article{alomari_kumar_hawary_murty_2022, title={High Temperature Deformation Behavior of a Fe-25Ni-20Cr (Wt Pct) Austenitic Stainless Steel}, volume={6}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-022-06739-6}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Alomari, Abdullah S. and Kumar, N. and Hawary, Mahmoud and Murty, K. L.}, year={2022}, month={Jun} }
 @article{tjayadi_kumar_murty_2020, title={Accelerated crack growth experiments of SS304H for dry storage canister in substitute ocean water - Effect of temperature}, volume={23}, ISBN={2352-4928}, DOI={10.1016/j.mtcomm.2020.100929}, abstractNote={Spent nuclear fuels (SNFs) are expected to be stored in dry storage canisters (DSCs) for much longer time than earlier anticipated due to a lack of permanent deep geological repository. As a result, DSCs located in marine environment may undergo chloride induced stress corrosion cracking (SCC) during long-term storage of SNFs. We report here the effect of test temperature on accelerated crack growth experiments carried out on sensitized austenitic stainless steel SS304H in substitute ocean water using fracture mechanics approach. Wedge-opening loading specimens were selected for measurement of crack growth rates using direct-current potential drop technique. Average crack growth rates of 0.975 × 10−10 ± 9.528 × 10-12, 3.258 × 10−10 ± 9.551 × 10-11 and 1.580 × 10-9 ± 2.593 × 10−10 m/s were obtained for 22, 37 and 60 °C, respectively resulting in an activation energy of 60.9 kJ/mol corresponding to diffusion of hydrogen in steel. Intergranular crack propagation was noted along with formation of chromium-rich carbide precipitates at grain boundaries.}, journal={MATERIALS TODAY COMMUNICATIONS}, author={Tjayadi, Leonardi and Kumar, Nilesh and Murty, Korukonda L.}, year={2020}, month={Jun} }
 @article{joshi_tillman_kumar_murty_cinbiz_2020, title={Biaxial Creep Behavior of Nb-Modified Zircaloys}, volume={206}, ISSN={["1943-7471"]}, DOI={10.1080/00295450.2019.1674581}, abstractNote={Abstract Zirconium-niobium (Zr-Nb) alloys are used as cladding materials to encapsulate radioactive fuel in nuclear reactors. They possess excellent corrosion resistance at high temperatures making it possible to achieve high fuel burnup, directly increasing the thermal efficiency of the reactor. While they are commonly used in recrystallized (Rx) form in boiling water reactors, there is a need to understand the effect of cold work and stress relief (CWSR) on the biaxial creep characteristics of these materials due to their use in pressurized water reactors. In this study, the biaxial creep behaviors of as-received Zr-Nb alloys, HANA and Zirlo®, have been investigated at 500°C and 400°C, respectively, using internally pressurized tubing superimposed with axial load under varied hoop σθ to axial σz stress ratios of 0 to 2 while monitoring both the axial and hoop strains using a linear variable displacement transformer and a laser telemetric extensometer, respectively. The crystallographic textures and creep loci of these as-received Zr-Nb alloys have been evaluated to correlate with the previous studies on recrystallized HANA4 and CWSR Zircaloy-4. The creep locus of HANA4 was found to be unaffected by initial state (CWSR or Rx) and showed close correspondence to planar isotropy while the creep locus of CWSR Zirlo exhibited more resistance to axial deformation than diametrical as per CWSR Zircaloy-4 reported earlier. These differences are shown to arise from grain-shape anisotropy of the CWSR Zirlo and Zircaloy-4. The simulated creep loci using crystallite-orientation distribution functions in conjunction with prism slip models showed excellent agreement with experimental results.}, number={5}, journal={NUCLEAR TECHNOLOGY}, author={Joshi, Pratik and Tillman, Micah and Kumar, Nilesh and Murty, Korukonda and Cinbiz, Nedim}, year={2020}, month={May}, pages={706–716} }
 @article{alsmadi_alomari_kumar_murty_2020, title={Effect of hold time on high temperature creep-fatigue behavior of Fe-25Ni-20Cr (wt.%) austenitic stainless steel (Alloy 709)}, volume={771}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2019.138591}, abstractNote={To understand high temperature creep-fatigue interaction of the Alloy 709, strain-controlled low-cycle fatigue (LCF) tests were performed at strain ranges varying from 0.3% to 1.2% with fully reversible cycle of triangular waveform at 750 °C. In addition, different hold times of 60, 600, 1800 and 3600 s were introduced at the maximum tensile strain to investigate the effect of creep damage on the fatigue-life at strain range of 1% at 750 °C. The creep-fatigue life and the number of cycles to macro-crack initiation and failure are found to decrease with increasing hold time indicating higher crack initiation and growth rates. Creep-fatigue life is evaluated by a linear summation of fractions of cyclic and creep damages according to ASME code. The fractographs of the samples deformed at 1% strain range indicated that fatigue might have been the dominant mode of deformation whereas, for the samples deformed at the same strain range with different hold times, both fatigue and creep have contributed to the overall deformation and fracture of the alloy.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Alsmadi, Zeinab Y. and Alomari, Abdullah and Kumar, N. and Murty, K. L.}, year={2020}, month={Jan} }
 @article{tjayadi_kumar_murty_2020, title={Stress Corrosion Cracking Behavior of Austenitic Stainless Steel SS304 for Dry Storage Canisters in Simulated Sea-Water}, ISBN={["978-3-030-36295-9"]}, ISSN={["2367-1696"]}, DOI={10.1007/978-3-030-36296-6_133}, abstractNote={A number of recent studies have suggested that dry storage canisters (DSCs) made of austenitic stainless steelAustenitic stainless steel SS304 to store spent nuclear fuel located along coastal region may undergo stress corrosion crackingStress corrosion cracking (SCCSCC ) if their useful life is extended due to lack of a permanent underground burial repository. It, therefore, becomes necessary to understand SCCSCC behavior of SS304 in marine environment. We report here our results on SCCSCC of SS304H in simulated sea-water using fracture mechanicsFracture mechanics approach as a function of temperature. The average crack growth ratesCrack growth rates were noted to be 0.975 × 10−10 ± 9.528 × 10−12, 3.258 × 10−10 ± 9.551 × 10−11, and 1.580 × 10−9 ± 2.593 × 10−10 m/s at 22, 37, and 60 °C, respectively. The activation energyActivation energy of the crack growth process was estimated to be 60.9 kJ/mol corresponding to diffusion of hydrogen in steelSteel . Optical microscopyMicroscopy revealed intergranular nature of the crack growth.}, journal={TMS 2020 149TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS}, author={Tjayadi, Leonardi and Kumar, Nilesh and Murty, Korukonda L.}, year={2020}, pages={1431–1442} }
 @article{pathak_kumar_mishra_de_2019, title={Aqueous Corrosion Behavior of Cast CoCrFeMnNi Alloy}, volume={28}, ISSN={["1544-1024"]}, DOI={10.1007/s11665-019-04329-z}, number={10}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, author={Pathak, S. and Kumar, N. and Mishra, R. S. and De, P. S.}, year={2019}, month={Oct}, pages={5970–5977} }
 @article{alomari_kumar_murty_2019, title={Creep Behavior and Microstructural Evolution of a Fe-20Cr-25Ni (Mass Percent) Austenitic Stainless Steel (Alloy 709) at Elevated Temperatures}, volume={50A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-018-5044-y}, number={2}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Alomari, Abdullah S. and Kumar, N. and Murty, K. L.}, year={2019}, month={Feb}, pages={641–654} }
 @article{tjayadi_kumar_murty_2019, title={Fracture Mechanics-Based Study of Stress Corrosion Cracking of SS304 Dry Storage Canister for Spent Nuclear Fuel}, ISSN={["2367-1696"]}, DOI={10.1007/978-3-030-05861-6_106}, abstractNote={Many independent spent fuel storage installations (ISFSI) are located along the coastal regions in the US and the dry storage canisters consisting of spent nuclear fuels are envisioned to undergo chloride-induced stress corrosionCorrosion cracking (SCCSCC ) in heat-affected zoneHeat-affected zone (HAZ) . In the present study, we have investigated SCCSCC behavior of sensitized SS304H under substitute ocean water at room temperature using wedge opening loading (WOL) specimens. The alloy was sensitized at 600 °C for 215 h followed by microstructural characterizationCharacterization . The crack growth during the test was monitored using direct current potential dropPotential drop technique. The crack growthCrack growth rate for the SS304H alloy was within the same order of magnitude as reported in literature for SS304 alloy under chloride environment.}, journal={TMS 2019 148TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS}, author={Tjayadi, Leonardi and Kumar, Nilesh and Murty, Korukonda L.}, year={2019}, pages={1089–1097} }
 @article{alomari_kumar_murty_2019, title={Serrated yielding in an advanced stainless steel Fe-25Ni-20Cr (wt%)}, volume={751}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2019.02.023}, abstractNote={Understanding serrated yielding behavior resulting from dynamic strain aging (DSA) is essential for design and safety considerations. In this work, uniaxial tensile tests were carried out at temperatures ranging from 298 to 1073 K and strain rates 10−5 – 10−3 s−1 followed by microstructural examination of Fe-25Ni-20Cr (wt%) austenitic stainless steel (Alloy 709), a candidate structural material for Sodium-cooled Fast Reactors. Serrated yielding was found to occur in this alloy in two temperature regimes; low-temperature serrated flow (LT-SF) from 498 to 648 K and high-temperature serrated flow (HT-SF) from 648 to 973 K (depending on the strain rate) with activation energies of 103 ± 13 kJ/mole and 204 ± 11 kJ/mole respectively. The critical strain for the occurrence of serrations was found to increase with strain rate as an exponential function with exponent (m + β) of 0.78 ± 0.1 and 1.56 ± 0.2 for the LT-SF and HT-SF regimes respectively. Based on the activation energies and m + β values, diffusion of interstitial atoms has been suggested to be responsible for serrated flow in the LT-SF regime while Cr atom migration was inferred to be responsible for DSA in the HT-SF regime. Manifestations of DSA in the Alloy 709 were observed including peaks and/or plateaus in flow stresses along with negative strain rate sensitivity at intermediate temperatures. However, no loss in ductility was observed within DSA regime attributed to the relatively high work hardening rate and strain-hardening exponent. The samples deformed in DSA regime showed planar substructure while equiaxed subgrains formed at higher temperatures. The fraction of low angle grain boundaries after deformation exhibited a valley at intermediate temperatures believed to be another manifestation of the DSA.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Alomari, Abdullah S. and Kumar, N. and Murty, K. L.}, year={2019}, month={Mar}, pages={292–302} }
 @article{kumar_alomari_murty_2018, title={Understanding thermally activated plastic deformation behavior of Zircaloy-4}, volume={504}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2018.03.031}, abstractNote={Abstract Understanding micromechanics of plastic deformation of existing materials is essential for improving their properties further and/or developing advanced materials for much more severe load bearing applications. The objective of the present work was to understand micromechanics of plastic deformation of Zircaloy-4, a zirconium-based alloy used as fuel cladding and channel (in BWRs) material in nuclear reactors. The Zircaloy-4 in recrystallized (at 973 K for 4 h) condition was subjected to uniaxial tensile testing at a constant cross-head velocity at temperatures in the range 293 K–1073 K and repeated stress relaxation tests at 293 K, 573 K, and 773 K. The minimum in the total elongation was indicative of dynamic strain aging phenomenon in this alloy in the intermediate temperature regime. The yield stress of the alloy was separated into effective and athermal components and the transition from thermally activated dislocation glide to athermal regime took place at around 673 K with the athermal stress estimated to be 115 MPa. The activation volume was found to be in the range of 40 b3 to 160 b3. The activation volume values and the data analyses using the solid-solution models in literature indicated dislocation-solute interaction to be a potential deformation mechanism in thermally activated regime. The activation energy calculated at 573 K was very close to that found for diffusivity of oxygen in α-Zr that was suggestive of dislocations-oxygen interaction during plastic deformation. This type of information may be helpful in alloy design in selecting different elements to control the deformation behavior of the material and impart desired mechanical properties in those materials for specific applications.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Kumar, N. and Alomari, A. and Murty, K. L.}, year={2018}, month={Jun}, pages={41–49} }
 @article{kumar_fusco_komarasamy_mishra_bourham_murty_2017, title={Understanding effect of 3.5 wt.% NaCl on the corrosion of Al0.1CoCrFeNi high-entropy alloy}, volume={495}, ISSN={0022-3115}, url={http://dx.doi.org/10.1016/j.jnucmat.2017.08.015}, DOI={10.1016/j.jnucmat.2017.08.015}, abstractNote={High entropy alloys are a new class of metallic materials with potential for use in a wide variety of applications including their use in corrosive environment. The present study focused on the corrosion behavior of a single-phase, face-centered cubic high entropy alloy (HEA) Al0.1CoCrFeNi in as-cast condition, and the results are compared with the corrosion behavior of the SS304. The microstructural characterization of the alloys in as-received condition was carried out using optical microscopy, electron backscattered diffraction, energy dispersive spectroscopy, and X-ray diffraction. Corrosion behavior was studied using potentiodynamic polarization test in a 3.5 wt% NaCl solution and electrochemical impedance spectroscopy at room temperature. It was observed that the general corrosion resistance of the HEA was better than that of SS304. Pitting potential of the HEA was found to be superior to that of the SS304. Corrosion pits size was slightly smaller in SS304 than that in the HEA. 3D imaging determined that the pit depths were of the same order in both cases. Overall, the HEA Al0.1CoCrFeNi demonstrated a better resistance to general and pitting corrosion.}, journal={Journal of Nuclear Materials}, publisher={Elsevier BV}, author={Kumar, N. and Fusco, M. and Komarasamy, M. and Mishra, R.S. and Bourham, M. and Murty, K.L.}, year={2017}, month={Nov}, pages={154–163} }
 @inproceedings{kumar_alomari_murty_2017, title={Understanding plastic deformation mechanism(s) in recrystallized Zircaloy-4}, DOI={10.1115/msec2017-2882}, abstractNote={It is essential to understand basic deformation mechanism(s) of conventional alloys in order to develop improved or novel alloys for their applications in much more challenging conditions. Zircaloy-4 is extensively used in pressurized water reactor for nuclear fuel cladding application. It operates at very high temperature in the presence of mechanical loads, corrosive atmosphere, and neutron irradiation environment. Present work explores the fundamental plastic deformation mechanism(s) of Zircaloy-4 in the temperature range 20 to 600 °C by subjecting tensile samples to uniaxial tensile loads under quasi-static deformation conditions. Based on the results of uniaxial tensile testing as a function of temperature, repeated stress-relaxation experiments were carried out to determine the activation volume of the alloy at 20 and 500 °C. The results from uniaxial tensile and stress-relaxation testing were used to gain insight into potential deformation mechanism(s) in Zircaloy-4.}, booktitle={Proceedings of the ASME 12th International Manufacturing Science and Engineering Conference - 2017, vol 2}, author={Kumar, N. and Alomari, A. and Murty, K. L.}, year={2017} }
 @article{kumar_mishra_dahotre_brennan_doherty_cho_2016, title={Effect of friction stir processing on microstructure and mechanical properties of laser-processed Mg-4Y-3Nd alloy}, volume={110}, DOI={10.1016/j.matdes.2016.08.039}, abstractNote={The development of advanced structural materials is dependent, among many factors, on the choice of manufacturing processes. Laser processing and friction stir processing (FSP) are two such advanced manufacturing processes. Individually, they have been studied quite extensively to understand their potential for developing high efficiency structures. However, there is no study describing the sequential integration of laser processing and FSP on microstructure and mechanical properties. The present study deals with FSP of the laser processed Mg4Y3Nd (WE43) alloy. The laser surface melting was carried out in air at 1800 W laser power, 30 mm/s laser speed, and 0.6 mm spot size on the surface using continuous wave Nd:YAG fiber laser followed by FSP of laser processed region at 500 rpm and 4 ipm. Scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy were carried out to understand microstructural evolution within the laser melted and friction stir processed regions. Mechanical properties were evaluated using uniaxial tensile testing at a strain-rate of 10− 3 s− 1. FSP led to significant improvement in strength and ductility of the laser processed material. An analysis of the strengthening mechanisms revealed that the dominant strengthening mechanism(s) in the WE43 alloy was dependent on the processing step.}, journal={Materials & Design}, author={Kumar, N. and Mishra, R. S. and Dahotre, N. B. and Brennan, R. E. and Doherty, K. J. and Cho, K. C.}, year={2016}, pages={663–675} }
 @article{lipscomb_fortier_kong_das_kumar_mishra_2016, title={Evaluation of plastic zone development in WE43 magnesium alloy upon friction stir processing using finite element modeling}, volume={673}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2016.07.051}, abstractNote={The evolution of the plastic zone in two different cases of WE43 magnesium alloy has been evaluated using finite element model (FEM) with a pressure load as the only loading condition. The FEM model for each of the two cases consists of WE43 material as follows: case 1: as-received (AR) condition and case 2: friction stir processed (FSP) condition. The simulations account for the stress behavior in the tear test specimen with and without the friction stir processing. A simple analytical model is developed to estimate the resulting stress gradient in each material which is considered as one of the main causes for fracture. The modeled stress in the specimens is presented and compared to experimental measurements generated with digital image correlation technology (DIC) for the two cases.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Lipscomb, Celena A. and Fortier, Aleksandra and Kong, Fanrong and Das, Shamiparna and Kumar, Nilesh and Mishra, Rajiv S.}, year={2016}, month={Sep}, pages={178–184} }
 @inproceedings{alagarsamy_fortier_mishra_kumar_2016, title={Investigation of thermo-mechanical processing and mechanical properties of CoCrFeNiMn high entropy alloy for peripheral vascular stent application}, DOI={10.1115/msec2016-8770}, abstractNote={High entropy alloys (HEAs) are a new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community however, their application is yet to be explored. This paper discusses the mechanical and microstructural behavior of CoCrFeNiMn HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rate. Results show that CoCrFeNiMn has characteristics that can potentially find use in peripheral vascular stent implants and extend their life-cycle.}, booktitle={Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 1}, author={Alagarsamy, K. and Fortier, A. and Mishra, R. and Kumar, N.}, year={2016} }
 @article{alagarsamy_fortier_komarasamy_kumar_mohammad_banerjee_han_mishra_2016, title={Mechanical Properties of High Entropy Alloy Al0.1CoCrFeNi for Peripheral Vascular Stent Application}, volume={7}, ISSN={["1869-4098"]}, DOI={10.1007/s13239-016-0286-6}, abstractNote={High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored. This paper discusses the mechanical behavior and microstructure of Al 0.1 CoCrFeNi HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rates. Results show that Al 0.1 CoCrFeNi alloy possesses characteristics that compare well against currently used stent materials and it can potentially find use in peripheral vascular stent implants and extend their life-cycle.}, number={4}, journal={CARDIOVASCULAR ENGINEERING AND TECHNOLOGY}, author={Alagarsamy, Karthik and Fortier, Aleksandra and Komarasamy, Mageshwari and Kumar, Nilesh and Mohammad, Atif and Banerjee, Subhash and Han, Hai-Chao and Mishra, Rajiv S.}, year={2016}, month={Dec}, pages={448–454} }