1、湖南大學碩士學位論文激光熔覆成形薄壁試件的工藝和顯微組織研究姓名：盧建剛申請學位級別：碩士專業(yè)：機械制造及其自動化指導教師：李力鈞20040310AbstractTheprocessandmicrostructureofLaserCladdingForming(LCF)thinpartsareexperimentallyandtheoreticallystudiedinthispaperandmainconclusionsareasfo

2、llows：1ApracticalLCFequipment，includinga1KWcontinuouswaveCOzlaserinstrument，athreeaxesCNCprocessingtableandapowderfeedingsystem，wasestablished，bywhichthinmetalcomponentswithbetteraccuracycanbebuilt2TheprocessofLCFthinwal

3、lhasbeenstudieddeeplyanda055mmwidththinpartwithlowercarbonsteelhasbeensuccessfullybuiltforthefirsttime；Next，Itwasinvestigatedsystematicallythatprocessparametershadaninfluenceonthewidthofthinwallindeposition；Finallyitwasf

4、oundthattheexperimentalresults，intermsoftheCROSSsectionofmoltenpool，areingoodagreementwiththatofthetheorywhichplaysanimportantroleinlyingoutanddeterminingprocessparameters3Thethinwall’SaccuracyofLCFhasalsobeeninvestigate

5、dbothexperimentallyandtheoreticallyitispresentedthatcoaxialpowderfeednozzle，laserbeammodescanningpathhavegreateffectsontheaccuracyinLCEforthechangesofthosefactorshavedirectinfluencesontheshapeandstabilityofmeltpool，Asare

6、sulttheaccuracyisonthedecline4Thelowercarbonsteelthinwall’SmicrostructureofLCFhasbeencarefuIlyanalyzedexperimentallyanditsmicrostructurewasmadeupoftinyequiaxedgrain，whichisentirelydifferentfromthatofcurrentreports；Bycomb

7、iningwiththeoryoffastcooling，themainreasonliesinthefactthatthesolidificationmicrostructurewouldgrowuptowardsequiaxedgrainunderlowerlaserpowerandsmallerlaserbeamdiameter；Inaddition，themiddlecarbonpart’SmicrostructureofLCF

8、ismainlybainite，alittleiSwustitestructure5Finally’themicrohardnessanddensityarealsoexaminedandexperimentalresultsareclosetOthoseoftraditionalprocesses，itshowsthatthinpartswithneardensitiesandbetterpropertiescanbefabricat