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dc.contributor.advisorBrewer, Luke
dc.contributor.authorBaker, Bradford W.
dc.dateSep-13
dc.date.accessioned2013-11-20T23:35:51Z
dc.date.available2013-11-20T23:35:51Z
dc.date.issued2013-09
dc.identifier.urihttp://hdl.handle.net/10945/37582
dc.descriptionApproved for public release; distribution is unlimiteden_US
dc.description.abstractA comprehensive set of processing, microstructure, and material property relationships is presented for friction stir welded oxide dispersion strengthened MA956 steel. Eight rotational and traverse speed combinations were used to produce friction stir welds on MA956 plates using a polycrystalline cubic boron nitride tool. Weld parameters with high thermal input produced defect-free, full penetration welds. Microstructural analysis showed a significant increase in grain size, a persistent body centered cubic torsional texture in the stir zone, a sharp transition in grain size from the thermo-mechanically affected zone into the stir zone, and an asymmetric reduction in hardness across the weld, all of which were sensitive to weld parameters. Oxide particles were significantly coarsened by friction stir welding resulting in a complete loss of particle strengthening. Base metal MA956 mechanical properties were determined up to 600C and the effect of friction stir welding on these properties was directly correlated to the evolved microstructure. Grain refinement is a dominant strengthening mechanism in the base metal and for all friction stir welding conditions, as the welding process removed essentially all dislocation and dispersion strengthening contributions. Friction stir welded MA956 retains a majority of its high temperature strength, making the alloy and joining method a suitable candidate for a structural material in advanced nuclear reactor designs.en_US
dc.publisherMonterey, California: Naval Postgraduate Schoolen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, may not be copyrighted.en_US
dc.titleProcessing, microstructure, and material property relationships following friction stir welding of oxide dispersion strengthened steelsen_US
dc.typeThesisen_US
dc.contributor.departmentMechanical And Aerospace Engineering
dc.subject.authorOxide Dispersion Strengthened Steelen_US
dc.subject.authorMA956en_US
dc.subject.authorFriction Stir Weldingen_US
dc.description.serviceCommander, United States Navyen_US
etd.thesisdegree.nameDoctor Of Philosophy In Mechanical Engineeringen_US
etd.thesisdegree.levelDoctoralen_US
etd.thesisdegree.disciplineMechanical Engineeringen_US
etd.thesisdegree.grantorNaval Postgraduate Schoolen_US


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