Bandini, A. (Department of Civil, Environmental and Materials Engineering (DICAM), University of Bologna) | Berry, P. (Department of Civil, Environmental and Materials Engineering (DICAM), University of Bologna)
Bewick, R.P. (MIRARCO - Mining Innovation, University of Toronto, Centre for Excellence in Mining Innovation) | Valley, B. (MIRARCO - Mining Innovation, Centre for Excellence in Mining Innovation) | Kaiser, P.K. (Centre for Excellence in Mining Innovation)
Shibanuma, KazukI (Department of Systems Innovation, The University of Tokyo) | Aihara, Shuji (Department of Systems Innovation, The University of Tokyo) | Matsubara, Motoyuki (Kubota Corporation) | Plant, Hanshin (Kubota Corporation) | Shirahata, Hiroyuki (Steel Research Laboratories, Nippon Steel Corporation) | Handa, Tsunehisa (Joining & Strength Research Department, JFE Steel Corporation)
Haugen, Veronica (NTNU (Norwegian University of Science and Technology)) | Rogne, Bjørn Rune Søraas (NTNU (Norwegian University of Science and Technology)) | Akselsen, Odd M. (NTNU (Norwegian University of Science and Technology)) | Thaulow, Christian (NTNU (Norwegian University of Science and Technology) ,and SINTEF) | Østby, Erling (SINTEF)
Completion devices such as fracturing balls, discs, and plugs are often used for downhole fluid and pressure control. Current polymer material must be milled away, flowed back or otherwise removed before production. Severe deformation of currently used materials that prevent flowback have been reported, requiring costly intervention operations to either remove or replace the tools and resulting in higher operational inefficiency. Using controlled electrolytic metallic (CEM) material eliminates this possibility. The new material is inherently designed for in-situ digestion in downhole environments at a controlled customizable rate.
Conventional degradable materials have a well-known tradeoff between dissolution rate and mechanical strength, which limits their utility. Increasing the dissolution rate often lowers the mechanical strength of the material below an acceptable threshold for many downhole applications. Using a reactive material with a blended nanostructured coating of ceramic and/or metallics provides the strength for initial operation and the ability to control the rate of corrosion later in the product's operation cycle. CEM materials have three times the strength of their base material and the corrosion rate can vary by a factor of several hundred, as compared to the base material. Corrosion rate could be further accelerated in HCl, thus providing operational flexibility. Experiments in various fluids and temperatures validate the corrodibility of CEM material.
This paper will present the chemistry and layering of the nanoscale coating within the grain structure, the unique material properties, and lab testing data of this truly interventionless nanostructured material technology.
Padekar, Bharat S. (IITB-Monash Research Academy) | Singh Raman, R.K. (Department of Mechanical & Aerospace Engineering & Department of Chemical Engineering Monash University) | Raja, V.S. (Department of Metallurgical Engineering and Materials Science Indian Institute of Technology Bombay) | Paul, Lyon (Magnesium Elektron Ltd)
Bruemmer, S.M. (Pacific Northwest National Laboratory) | Olszta, M.J. (Pacific Northwest National Laboratory) | Toloczko, M.B. (Pacific Northwest National Laboratory) | Thomas, L.E. (Pacific Northwest National Laboratory)
ABSTRACT Grain boundary microstructures and microchemistries are examined in cold-rolled alloy 690 materials and comparisons are made to intergranular stress corrosion cracking (IGSCC) behavior in PWR primary water. Chromium carbide precipitation is found to be a key aspect for materials in both the mill annealed and thermally treated conditions. Cold rolling to high levels of reduction was discovered to produce small IG voids and cracked carbides in alloys with a high density of grain boundary carbides. The degree of permanent grain boundary damage from cold rolling was found to depend directly on the initial IG carbide distribution. For the same degree of cold rolling, alloys with few IG precipitates exhibited much less permanent damage. Although this difference in grain boundary damage appears to correlate with measured SCC growth rates, crack tip examinations reveal that cracked carbides appeared to blunt propagation of IGSCC cracks in many cases. Preliminary results suggest that the localized grain boundary strains and stresses produced during cold rolling promote IGSCC susceptibility and not the cracked carbides and voids. INTRODUCTION Intergranular stress corrosion cracking (IGSCC) of Fe- and Ni-base austenitic stainless alloys has been a continuing problem in commercial boiling-water-reactor (BWR) and pressurized-water- reactor (PWR) nuclear power plants. Grain boundary microstructure and microchemistry has been shown to play a controlling role in the observed cracking for most cases. This was clearly the case for BWR failures in Fe-base 300-series stainless steel components that were often due to Cr-carbide precipitation and concurrent Cr depletion (thermal sensitization) during fabrication.1,2 Although sensitization remains an issue for Ni-base stainless alloy 600 in oxidizing BWR water environments, it is not a controlling process in PWR primary water. Nevertheless, grain boundary carbide distributions have been shown to influence IGSCC susceptibility with thermally treated material showing improved behavior versus mill-annealed material.3,4
Zhu, Yakun (Department of Metallurgical Engineering, University of Utah) | Kar, Soumya (Department of Metallurgical Engineering, University of Utah) | Free, Michael L. (Department of Metallurgical Engineering, University of Utah) | Cullen, David A. (Materials Science & Technology Division, Oak Ridge National Laboratory) | Allard, Lawrence F. (Materials Science & Technology Division, Oak Ridge National Laboratory)