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1、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
2、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16AbstractGraycastironhasgoodcastingproperties,goodvibration,goodwearresistance,goodmachiningperformance,lownotch
3、sensitivity.Graycastironwelding,theweldedjointismoreinclinedtocrack,whichmainlyrelatedtotheperformanceoftheircastiron,weldingstress,jointorganizationsandtherelevantchemicalconstituents.Inordertopreventcrackingwhenweldingintheproductionofthemainweldingtotaketoreducestress,changeinweldalloysystems,asw
4、ellasrestrictionsonimpuritiesinmaterials,suchasmeasurestomeltintotheweld.Toobtaingoodweldingquality,notonlyinaccordancewiththerequirementsofthecorrectchoiceforrepairingweldingmaterialandweldingtechnologytograspthemainpointsofattention.Heterogeneityofthearcweldcoldweldingprocesscanbesummarizedinfours
5、entencesthemainpoints:"thepreparatoryworktodo,anappropriateweldingcurrentsmall,shortparagraphsscatteredintermittentwelding,weldingKnockwithahammersmallimmediatelyafter."Preparatoryworkbeforeweldingisveryimportant,usuallyreferstoremovaldefectsWeldmentoilandotherimpurities,thecorrectobservationofdefec
6、ts(suchasthelengthofcracks,etc.)anddefectsintheappropriategroovemadetoprepareforwelding.Castironclean-upmethodsusedtherearetwotypesoftheuseofgrindingwheel,wirebrushoraflatshovelandothertoolsofthemechanicalcleaningmethod;theotheristheuseoftrichlorethylene,causticsoda,gasoline,acetoneandotherchemicals
7、ofthechemicalsolventwashing.Oilcanalsobeusedtoremovetheflamewillbesub-castingheat,untilheatedtonotsmokeorwelddefectssuchasporeseasily.Topreventexcessivethermalstress,theheatingtemperatureshouldbecontr
