Wednesday, April 11, 2012

Future Naval Force May Sail With Strength Of Titanium

Steel may have met its match: An Office of Naval Research (ONR)-funded project will produce a full-size ship hull section made entirely with marine grade titanium using a welding innovation that could help bring titanium into future Navy ship construction, officials announced April 3. The contractor team building this section recently completed the industry's longest friction-stir titanium alloy welds and aims to complete the ship hull section this summer. Friction-stir welds more than 17 feet long joined the titanium alloy plates for the section's deck. "This fast, effective friction-stir weld technique is now an affordable manufacturing process that takes advantage of titanium's properties," said Kelly Cooper, the program officer managing the project for ONR's Sea Warfare and Weapons Department. Titanium metal and its alloys are desirable materials for ship hulls and other structures because of their high strength, light weight and corrosion-resistance. If constructed in titanium, Navy ships would have lighter weight for the same size-allowing for a bigger payload-and virtually no corrosion. But because titanium costs up to nine times more than steel and is technically difficult and expensive to manufacture into marine vessel hulls, it has been avoided by the shipbuilding industry. But perhaps not for much longer. Researchers at the University of New Orleans School of Naval Architecture and Textron Marine and Land Systems are demonstrating the feasibility of manufacturing titanium ship hull structures. Using lower cost marine grades of titanium, they fabricated a 20-foot-long main deck panel-composed of six titanium plates, joined together by friction-stir welding, as part of technology studies for an experimental naval vessel called Transformable Craft, or T-Craft. Since antiquity, blacksmiths have joined iron or steel parts together by heating them in a forge, placing them on an anvil and striking the two pieces repeatedly with a heavy hammer. After several repetitions of heating and striking, the two pieces were "hammer forged" or "forge welded" together.Friction-stir welding joins metals using the heat of friction produced by a spinning pin tool pressed down on both pieces of metal at their common joint. Friction heating produced by the high-speed rotation causes both metal pieces to heat up to a "plastic" condition, but not to melt. As the tool passes down the common joint line, the heated, plasticized metal from both pieces is kneaded together in the rotating tool's wake, forming the weld between them. Friction-stir welding works well for most aluminum alloys. Titanium, however, is difficult to join by the same process because of the high temperatures required, and pin tool materials that erode and react with titanium, weakening the weld. The researchers overcame that problem by using new titanium friction-stir welding methods developed by Florida-based Keystone Synergistic Enterprises Inc., with funding from both ONR and the Air Force. The processes were scaled up and transferred to the National Center for Advanced Manufacturing (NCAM), which is a partnership between the University of New Orleans, NASA and the state of Louisiana. To fabricate the ship hull structure, more than 70 feet of welded linear joints were made, the longest known welds in titanium made with the friction-stir process. This friction stir welding achievement showed a noticeable improvement from previous similar processes. It was made at a high linear speed, indicating reduced manufacturing time; showed excellent weld penetration, indicating a secure connection; and had no distortion of the titanium adjoining the weld. Experts attribute the success to an effective design of the pin tool, process parameters that emphasized pin tool life and exact duplication of the process steps from facility to facility and machine to machine. ONR funds collaborative projects investigating novel shipbuilding materials and improved processes for titanium friction-stir welding, especially its affordability, as part of the Sea Base Enabler Innovative Naval Prototype program.

Friday, April 06, 2012

Navy Jet Crashes In Virginia

A Navy jet has crashed near a major road in Virginia Beach, an official with the Federal Aviation Administration confirmed to Fox News. The pilot is believed to have ejected safely from the jet, the official said. There is no word on injuries. Emergency crews from the military, Virginia State Police and Virginia Beach police are all responding to the scene of the crash. Virginia Department of Transportation traffic cameras showed black smoke rising from the Birdneck Road area of Virginia Beach at 12:30 p.m. local time.

Thursday, April 05, 2012

US To Sink Ghost Ship Dislodged By Japan Tsunami

The lonely voyage of a rusting, unmanned Japanese ship that has floated thousands of miles since it was dislodged by last year's tsunami appeared to be coming to an end in the Gulf of Alaska. The U.S. Coast Guard was gearing up to use cannon fire to sink the shrimping vessel, which was floating 180 miles southwest of the southeast Alaska town of Sitka Thursday morning. "Something like this hasn't been done, based on the tsunami," Coast Guard spokesman Paul Webb said. "It's a new one for all of us." The 164-foot Ryou-Un Maru, which has no lights or communications system, has a tank that could carry more than 2,000 gallons of diesel fuel, but officials don't know how much, if any, is aboard. Either way, the government says the move is safer environmentally than letting the ship continue to drift. "It's less risky than it would be running into shore or running into (maritime) traffic," Webb said. The vessel had been destined for scrapping when the Japan earthquake struck, so there is no cargo on board, according to Webb. He said it's likely there is little or no fuel on board because the ship has been traveling high in the water, indicating a light ballast. Webb said he doesn't know who owns the Ryou-Un Maru, which has been traveling about 1 mile per hour in the past days.A Coast Guard cutter was at the location of the ghost ship Thursday with plans to fire cannons loaded with high explosive rounds to sink the vessel in calm seas and clear weather. Webb said the cutter would fire the cannons from several hundred feet away. The goal is to punch holes in the Ryou-Un Maru and sink it. A Coast Guard C-130 plane crew will monitor the operation. The National Oceanic and Atmospheric Administration and the Environmental Protection Agency studied the problem and decided it is safer to sink the ship and let the fuel evaporate in the open water. The Coast Guard will warn other ships to avoid the area, and will observe from an HC-130 Hercules airplane. The vessel has been adrift from Hokkaido, Japan, since it was launched by the tsunami caused by the magnitude-9.0 earthquake that struck Japan in March 2011. About 5 million tons of debris were swept into the ocean by the tsunami. The Japan earthquake triggered the world's worst nuclear crisis since the Chernobyl accident in 1986, but Alaska state health and environmental officials have said there's little need to be worried that debris landing on Alaska shores will be contaminated by radiation. They have been working with federal counterparts to gauge the danger of debris including material affected by a damaged nuclear power plant, to see if Alaska residents, seafood or wild game could be affected. In January, a half dozen large buoys suspected to be from Japanese oyster farms appeared at the top of Alaska's panhandle and may be among the first debris from the tsunami.

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