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1、大型LNG儲罐用9Ni鋼焊接工藝與機理研究摘要本文針對大型液化天然氣(LNG)儲罐對9Ni鋼的焊接需求,系統(tǒng)研究了9Ni鋼的焊條電弧焊(SMAW)、鎢極氬弧焊(GTAW)和埋弧焊(SAW)的焊接工藝與機理。利用光學顯微鏡、掃描電鏡及能譜分析、強度測試和硬度測試等方法,分別研究了9Ni鋼焊接接頭的界面顯微組織和力學性能。通過研究工藝參數(shù)對接頭微觀組織和力學性能的影響,優(yōu)化了焊接工藝,闡明了接頭不同特征區(qū)域的斷口特性。通過對比分析三種焊接方法在大型LNG儲罐生產(chǎn)中的適用性,確定底板和壁板不同位置焊縫需要選擇的最佳焊接方法。通過對比分析三種焊接方法可知:大型LNG儲罐的現(xiàn)場焊接方法最好采用
2、以上三種方法的組合,其中,底板的平位置焊縫最好采用焊條電弧焊或鎢極氬弧焊方法;壁板的橫位置焊縫最好采用埋弧焊方法;壁板的立位置焊縫最好采用焊條電弧焊或鎢極氬弧焊方法的多層多道焊;而底板與壁板的接縫是平角縫,最好采用埋弧焊方法。關鍵詞:9Ni鋼;焊接方法;界面結構;力學性能LargeLNGtankswithsteelweldingand9NimechanismresearchABSTRACTThisarticleinviewofthelargeliquefiednaturalgas(LNG)of9Nitanksofsteelweldingdemand,thesystematicstud
3、yofthesteelelectrode9Nielectricarcwelding(SMAW),tungstenextremelyargonarcwelding(GTAW)andsubmergedarcwelding(SAW)oftheweldingprocessandmechanism.Useofopticalmicroscopy,scanningelectronmicroscopeandenergyspectrumanalysis,strengthandhardnesstestingmethodsoftest,arestudiedandNisteelweldingjointmic
4、rostructureofinterfaceandmechanicalproperties.Throughtheresearchprocessparametersonthejointmicrostructureandmechanicalpropertiesoftheinfluence,theoptimizationofweldingtechnology,andexpoundsthecharacteristicsofdifferentregionjointfracturecharacteristics.Throughthecomparisonandanalysisofthethreew
5、eldingmethodinlargeLNGtankstheapplicabilityofproduction,todeterminethebottomandwallplateweldneedtochoosedifferentpositionsofthebestweldingmethod.ThroughthecomparisonandanalysisofthethreekindsofweldingmethoditistoknowthatthelargeLNGstoragetankweldingmethodhadbetterusethecombinationofthreekindsof
6、methods,amongthem,theflatbottompositionhadbetterusetheelectricarcweldingelectrodeortungstenextremelyargonarcweldingmethods;Wallplateofhorizontalpositionweldhadbetterusesubmergedarcweldingmethods;Wallplatemadeofweldhadbetteruseelectrodepositionelectricarcweldingortungstenargonarcweldingmethodofm
7、ulti-layeramulti-channelwelding;Andbottomandwallplatetheseamsoftheflatisseam,hadbetterusesubmergedarcweldingmethod.KEYWORDS:Keywords:9Nisteel,Weldingmethod,Interfacalmicrostructure,Mechanicalproperties目 錄前 言1第1章緒論21.1課題背景21.29Ni鋼材