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摘要 灰铸铁有良好的铸造性能、良好的减振性、良好的耐磨性能、良好的切削加工性能、低的缺口敏感性。 灰铸铁焊接时,焊接接头中裂纹倾向是比较大的,这主要与铸铁本身的性能、焊接应力、接头组织及化学成分有关。为防止焊接时产生裂纹,在生产中主要时采取减小焊接应力,改变焊缝合金系统以及限制母材中杂质熔入焊缝等措施。要获得好的焊接质量,不仅要根据补焊要求来正确选择焊接材料,而且要注意掌握焊接工艺要点。异质焊缝的电弧冷焊工艺要点可归纳为四句话:“准备工作要做好,焊接电流适当小,短段断续分散焊,焊后立即小锤敲”。焊前准备工作很重要,通常是指清除焊件缺陷处的油污等其它杂质,正确观察缺陷的情况(如裂纹的长度等)及将缺陷制成适当的坡口,以备焊接。 常用的铸铁清理方法有两种,一种采用砂轮、钢丝刷或扁铲等工具的机械清理法;另一种是采用三氯乙烯、苛性钠、汽油、丙酮等化学溶剂洗涤的化学方法。清除油污也可用火焰将铸件分段加热,加热到不冒烟为止,否则焊缝易出现气孔等缺陷。为防止产生过大的热应力,加热温度应控制在400℃以下。 关键词:加热减应区、灰铸铁、石墨形式、焊后缓冷、铸铁型焊缝、淬硬组织、整体预热 Abstract Graycastironhasgoodcastingproperties,goodvibration,goodwearresistance,goodmachiningperformance,lownotchsensitivity.Graycastironwelding,theweldedjointismoreinclinedtocrack,whichmainlyrelatedtotheperformanceoftheircastiron,weldingstress,jointorganizationsandtherelevantchemicalconstituents.Inordertopreventcrackingwhenweldingintheproductionofthemainweldingtotaketoreducestress,changeinweldalloysystems,aswellasrestrictionsonimpuritiesinmaterials,suchasmeasurestomeltintotheweld.Toobtaingoodweldingquality,notonlyinaccordancewiththerequirementsofthecorrectchoiceforrepairingweldingmaterialandweldingtechnologytograspthemainpointsofattention.Heterogeneityofthearcweldcoldweldingprocesscanbesummarizedinfoursentencesthemainpoints:"thepreparatoryworktodo,anappropriateweldingcurrentsmall,shortparagraphsscatteredintermittentwelding,weldingKnockwithahammersmallimmediatelyafter."Preparatoryworkbeforeweldingisveryimportant,usuallyreferstoremovaldefectsWeldmentoilandotherimpurities,thecorrectobservationofdefects(suchasthelengthofcracks,etc.)anddefectsintheappropriategroovemadetoprepareforwelding.Castironclean-upmethodsusedtherearetwotypesoftheuseofgrindingwheel,wirebrushoraflatshovelandothertoolsofthemechanicalcleaningmethod;theotheristheuseoftrichlorethylene,causticsoda,gasoline,acetoneandotherchemicalsofthechemicalsolventwashing.Oilcanalsobeusedtoremovetheflamewillbesub-castingheat,untilheatedtonotsmokeorwelddefectssuchasporeseasily.Topreventexcessivethermalstress,theheatingtemperatureshouldb