焊接专业英语 教学课件 作者 洪宇翔 Unit 6.pptx

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1、Unit6TextGasMetalArcWeldingThefollowingareconsideredtobesomeofthemoreimportantadvantagesofGMAW:1.Sincethereisnofluxorslagandverylittlespattertoremove,thereisaconsiderablesavingintotalweldingcost.[2]Generallyspeaking，weldcleanupisoftenmorecostlythanactualweldingtime.2.

2、Lesstimeisrequiredtotrainanoperator.AsamatteroffactweldingoperatorswhoareproficientinotherweldingprocessescanusuallymasterthetechniqueofGMAWinamatterofhours.Alltheoperatorhastodoispulltheguntriggerandweld.Hismainconcernistowatchtheangleoftheweldinggunandspeedoftravel.

3、3.Theweldingprocessisfasterespeciallywhencomparedwithmetallicarcstickwelding.Thereisnoneedtostartandstopinordertochangeelectrode.Asaruleweldfailuresareoftenduetothestartingandstoppingofwelding,sincethisconditioninducesslaginclusions,coldlappingandcratercracking.[3]4.B

4、ecauseofthehighspeedoftheGMAWprocess,bettermetallurgicalbenefitsareimpartedtotheweldarea.Withfastertravelthereisanarrowerheat-affectedzoneandconsequentlylessmoleculardisarrangement,lessgraingrowth,1essheattransferintheparentmetal,andevenmoreimportant,greatlyreduceddis

5、tortion.[4]5.Althoughoriginallygastungstenarcwelding(GTAW)wasconsideredmorepracticalforweldingthinsheet,becauseofitslowercurrent,thedevelopmentoftheshortcircuitingtransfertechniquenowmakesitpossibletoweldthinstockequallyaseffectivelywiththeGMAWprocess.6.SinceGMAWhasde

6、eppenetratingcharacteristics,narrowerbeveledjointdesigncanbeused.Furthermore,thesizeoffilletweldsisreducedbycomparisontootherweldingmethods.NewWordsandPhrasesseam[si:m]n.缝，接缝proficient[prə'fiʃənt]a.精通的，熟练的trigger['trigə]n.扳机，触发器，起动装置slag[slæg]n.炉渣，熔渣，矿渣inclusion[in'kl

7、u:ʒən]n.包括，包含disarrangement[,disə'reindʒmənt]n.扰乱beveled['bevld]a.形成斜面的optimum['ɔptiməm]a.最理想的n.最佳效果，最适宜条件magnesium['mæg'ni:ʃiəm]n.镁shallow['ʃæləu]a.浅的，浅薄的,肤浅的erratic[i'rætik]a.古怪的，不稳定的globular['glɔbjulə]a.球状的，全球的，闻名世界的semi-automatic半自动（的）Notes[1]Thewireelectrodeisfed

8、throughthetorchatpresetcontrolledspeeds.Theshieldinggasisalsofedthroughthetorch.熔池被一层保护气体完全覆盖。焊丝以预先调好的速度通过焊炬，保护气体也通过焊炬输送。[2]