Studies on the performance of welded joints produced by friction stir welding process

Abstract

Friction Stir Welding (FSW) is a relatively new technology developed by The Welding newlineInstitute (TWI), U.K and patented in 1991, which was industrialized within five years of newlineits development. FSW is the only solid state welding process that can be employed for newlinebutt, lap, T and orbital type joints when compared with other solid state welding newlineprocesses. The welded joints prepared by FSW has the properties almost same as that of newlineparent material, which is not possible by fusion welding process. newlineFSW is considered to be the most significant development in metal joining and is a newline green technology due to its energy efficiency, environment friendliness, and newlineversatility. As compared to the conventional welding methods, FSW consumes newlineconsiderably less energy and there is no requirement of cover gas or flux. FSW does not newlineinvolve use of any filler metal because there is absence of melting. Therefore many newlinemetals including aluminum alloy can be joined without concern for the compatibility of newlinecomposition, solidification cracking, distortion and loss of alloying element which are the newlineissues associated with fusion welding. newlinePublished literature indicates that FSW has been used to weld lower wings, fuselages, newlineempennages, aviation fuel tanks, external throw away tanks for military aircraft, newlinecryogenic fuel tanks and repair of faulty MIG (Metal Inert Gas) welds. FSW also finds newlineapplication in automobile, transportation, ship building, railways and construction newlineindustries. newlineFSW can be successfully used to weld precipitate hardenable aluminum alloys which are newlinedifficult to weld by fusion welding process like Gas Metal Arc Welding and Gas newlineTungsten Arc Welding process. The 2XXX, 5XXX, 6XXX and 7XXX aluminum alloys newlinewhich are difficult to weld by fusion welding process can be easily welded using FSW newlineprocess. These Aluminum alloys are extensively used in aerospace, aircraft structures, newlineautomobile, transportation, ship building, railways and construction industries. newlineThe specific objectives of the present investigation have been to understand the