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 [1];  [1];  [2]
  1. ORNL
  2. University of Tennessee, Knoxville (UTK)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
FE USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: International conference on Solid-Solid Phase Transformations in Inorganic Materials, Whistler, BC, Canada, 20150628, 20150703
Country of Publication:
United States

Citation Formats

Shassere, Benjamin, Yamamoto, Yukinori, and Babu, Prof. Sudarsanam Suresh. CONTROL OF NANO-SCALE MX DISPERSION IN GRADE 91 STEEL THROUGH THERMO-MECHANICAL TREATMENT. United States: N. p., 2015. Web.
Shassere, Benjamin, Yamamoto, Yukinori, & Babu, Prof. Sudarsanam Suresh. CONTROL OF NANO-SCALE MX DISPERSION IN GRADE 91 STEEL THROUGH THERMO-MECHANICAL TREATMENT. United States.
Shassere, Benjamin, Yamamoto, Yukinori, and Babu, Prof. Sudarsanam Suresh. 2015. "CONTROL OF NANO-SCALE MX DISPERSION IN GRADE 91 STEEL THROUGH THERMO-MECHANICAL TREATMENT". United States. doi:.
author = {Shassere, Benjamin and Yamamoto, Yukinori and Babu, Prof. Sudarsanam Suresh},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 1

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  • Two different approaches have been proposed for improvement of cross-weld creep properties of the high temperature ferrous structural materials for fossil-fired energy applications. The traditional creep strength-enhanced ferritic (CSEF) steel weldments suffer from Type IV failures which occur at the fine-grained heat affected zone (FGHAZ). In order to minimize the premature failure at FGHAZ in the existing CSEF steels, such as modified 9Cr-1Mo ferritic-martensitic steels (Grade 91), a thermo-mechanical treatment consisting of aus-forging/rolling and subsequent aus-aging is proposed which promotes the formation of stable MX carbonitrides prior to martensitic transformation. Such MX remains undissolved during welding process, even in FGHAZ,more » which successfully improves the cross-weld creep properties. Another approach is to develop a new fully ferrtic, creep-resistant FeCrAl alloy which is essentially free from Type IV failure issues. Fe-30Cr-3Al base alloys with minor alloying additions were developed which achieved a combination of good oxidation/corrosion resistance and improved tensile and creep performance comparable or superior to Grade 92 steel.« less
  • The Laser Inertial Fusion-based (LIFE) engine is an advanced energy concept under development at Lawrence Livermore National Laboratory (LLNL). LIFE engine could be used to drive a subcritical fission blanket with fertile or fissile fuel. Current LIFE engine designs envisages fuel in pebble bed form with TRISO (tristructural isotropic) particles embedded in a graphite matrix, and pebbles flowing in molten salt Flibe (2LiF+BeF{sub 2}) coolant at T {approx} 700C. Weapons-grade plutonium (WGPu) fuel is an attractive option for LIFE engine involving the achievement of high fractional burnups in a short lifetime frame. However, WGPu LIFE engine operating conditions of highmore » neutron fast fluence, high radiation damage, and high Helium and Hydrogen production pose severe challenges for typical TRISO particles. The thermo-mechanical fuel performance code HUPPCO (High burn-Up fuel Pebble Performance COde) currently under development accounts for spatial and time dependence of the material elastic properties, temperature, and irradiation swelling and creep mechanisms. In this work, some aspects of the thermo-mechanical response of TRISO particles used for incineration of weapons grade fuel in LIFE engine are analyzed. Preliminary results show the importance of developing reliable high-fidelity models of the performance of these new fuel designs and the need of new experimental data relevant to WGPu LIFE conditions.« less
  • Effect of aluminum on the decomposition of 5 ferrite to austenite was investigated in a low-alloy steel weld. In addition, the effect of inclusion composition on the transition from bainite to acicular ferrite during austenite decomposition was analyzed. Stress relaxation during decomposition of austenite to allotriomorphic and acicular ferrite was also characterized. Results from the above experiments illustrate the importance of thermomechanical effects on weld microstructure evolution.
  • A coupled finite-element model has been developed to simulate the thermal-mechanical behavior of a transverse slice through the solidifying steel shell as it moves down through the mold and upper support rolls in the spray chamber of a continuous slab-casting machine. The heat transfer model incorporates the effect on solidification of superheat delivered by turbulent flow in the liquid pool. The stress model evaluates the highly non-linear elastic-visco-plastic constitutive equations using an efficient time iteration algorithm which alternates between local and global levels. The stress model assumes a stress state of generalized plane strain and employs an efficient contact algorithmmore » to achieve reasonable deformation of the shell, under the influence of internal ferrostatic pressure. The two models, which are coupled together through the size of the interfacial gap between the shell and the mold, have been validated with analytical solutions and plant measurements. Separate mathematical models have been applied to simulate fluid flow and heat transfer within the melting powder layer on the top surface of the liquid pool and thermal distortion of the mold. Together, these models are used to illustrate a multi-stage mechanism for the formation of longitudinal off-corner depression defects or gutters during continuous casting of steel slabs. Specifically, the depressions form during bulging below the mold, as a result of inadequate heat flow in the mold in the off-corner wide face region. The results suggest ways to avoid the problem that are consistent with industrial experience.« less