第1页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第1页共7页第2页共7页第1页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第2页共7页第3页共7页第2页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第3页共7页第4页共7页第3页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第4页共7页第5页共7页第4页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第5页共7页第6页共7页第5页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第6页共7页BlackdepositonandbesidestheweldWithmanyapplications(palletsforthechemicalandfoodindustry,ladders,scaffoldings)theblackdepositisratherdisturbing.Simplebrushingremovesit,however,requiresadditionaloperationswhichcanoftenbedoneonlymanuallyatareasoflimitedaccess.ThedepositresultsfromevaporationandfollowingfalloutofMagnesiumoxide.MagnesiumisanalloyingelementofAluminiumwhichsubstantiallyincreasesitsstrengthandcannotbeleftoutinmostcases.第7页共7页第6页共7页编号:时间:2021年x月x日书山有路勤为径,学海无涯苦作舟页码:第7页共7页Magnesiumoxideisusuallyknownwithwhitecolour.AnEDS-analysiseliminateseverydoubtofnotbeingMgOwhichisknowntoshowcoloursofgrey,yellow,brownorblackbesidesitswhiteformofexistence.ThefollowingpossibilitiesexisttopreventMgO-formation:UseofwireelectrodeswithlowornoMgcontent(AlMg3,AlSi5)OptimisedpulseparametersforthelowestpossibleformationofmetalvapourAvoidpooraccessibilityandresultingunfavourabletorchpositionSufficientshielding-gasprotectiontokeeptheintakeofOxygenaslowaspossible