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Port Hueneme, CA, United States

Young G.W.,NAVFAC ESC | Stewart W.C.,U.S. Navy | Steel R.,Megastir Technologies | Babb J.,Megastir Technologies | And 2 more authors.
TMS Annual Meeting | Year: 2013

Microstructures and mechanical property changes associated with Friction Stir Processing (FSP) of HY-80 steel both dry and under seawater were examined. FSP on HY-80 plates employed a PCBN / tungsten rhenium tool operating at 400 rpm and 2 ipm. Microstructural characterization of the as-received HY-80 plate emphasized the differences in the distribution of constituent phases and inclusions in the rolling, transverse and normal planes using optical and scanning electron microscopy. Microstructural details of transverse sections as well as the plan section at the tool extraction sites of processed plates were also evaluated. Mechanical properties of these samples were evaluated by tensile tests, microhardness tests and Charpy V-notch impact tests. Residual hydrogen content was also evaluated. Stir zones exhibited untempered bainitic / martensitic microstructures with minimal hydrogen pick up but distinct property gradients from stir zone to base metal. The influence of a post-FSP tempering treatment also is summarized.

Paulson K.P.,NAVFAC ESC | Wang J.,University of Florida | Topham N.,University of Florida | Wu C.Y.,University of Florida | And 3 more authors.
Transactions - Society of Naval Architects and Marine Engineers | Year: 2011

Welding stainless steel generates hazardous air pollutants. Two technologies were developed to reduce these HAPs. The first, Tetramethylsilane is added to the welding shield gas, and welding proceeds as normal. Reactive oxygen species are consumed and the resulting metal jume particles are encapsulated. In the second technique, new chromium-free welding consumables are introduced nearly eliminating Cr(VI) in the welding Jume.

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