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1、BlackdepositonandbesidestheweldWithmanyapplications(palletsforthechemicalandfoodindustry,ladders,scaffoldings)theblackdepositisratherdisturbing.Simplebrushingremovesit,however,requiresadditionaloperationswhichcanoftenbedoneonlymanuallyatareasoflimitedaccess.Thedepositresultsfromevaporationandfollowi
2、ngfalloutofMagnesiumoxide.MagnesiumisanalloyingelementofAluminiumwhichsubstantiallyincreasesitsstrengthandcannotbeleftoutinmostcases.Magnesiumoxideisusuallyknownwithwhitecolour.AnEDS-analysiseliminateseverydoubtofnotbeingMgOwhichisknowntoshowcoloursofgrey,yellow,brownorblackbesidesitswhiteformofexis
3、tence.ThefollowingpossibilitiesexisttopreventMgO-formation: UseofwireelectrodeswithlowornoMgcontent(AlMg3,AlSi5) Optimisedpulseparametersforthelowestpossibleformationofmetalvapour Avoidpooraccessibilityandresultingunfavourabletorchposition Sufficientshielding-gasprotectiontokeeptheintakeofOxygenaslowaspossible