Liccoln WPHB - Section 08 (Welding Cast Iron and Cast Steel)

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1、Section8WELDINGCASTIRONANDCASTSTEELSECTION8.1WELDINGCASTIRONPageTypesofCastIron....................8.1-1ElectrodesforCastIron................8.1-2WeldingGrayandMalleableIrons........8.1-2ElectrodeSelectionandWeldingGuidelines........................8.1-2PreparationsforRepairWelding.

2、.......8.1-3WeldingDuctileIron...................8.1-6SECTION8.2WELDINGCASTSTEELPreparationforWelding................8.2-1EffectsofWelding.....................8.2-2TheWeldingOperation.................8.2-28.1-1WeldingCastIronTypesofCastIronTherearefourmajortypesofcastiron-graycastas

3、thefirststepinthemakingofmalleableiron,malleableiron,ductile(nodular)iron,andiron,amuchmoreusefulmaterial.white(orchilled)iron.Mostcast-ironpartsareMalleableIron:Thismaterialisawhitecastmadeingrayiron.Graycastiron,malleableironironthathasbeenheattreatedbyalongannealingandductile(nod

4、ular)ironaredifficulttoweldbutprocess(usuallylasting2or3days)thatchangestheycanbeweldedwhentheproperproceduresarethecombinedcarbon(ironcarbideorcementite)used.Malleableironandductileironrequirelongintoironandauniformlydistributed"tempercarbon"postheattreatmenttorestoretheirnormalstr

5、ength(ferriteandfreegraphite).Thisheattreatmentandductility.Whiteiron,ontheotherhand,issoincreasesbothstrengthandductility.Malleableirondifficulttoweldthatitisgenerallyconsideredtoisverymuchtougherthanwhiteorgraycastironbeunweldable.Approximatecompositionsoftheseandcanbebentanapprec

6、iableamount.GraycastmaterialsarelistedinTable8-1.ironwillbreakinabrittlefashionwithverylittleGrayIron:Thismaterialisthemostcommonbending.Whitecastironwillbreaklikeglasswithtypeofcastiron,anditcanbeweldedifcertainessentiallynobending.Whenmalleableironisprecautionsareobservedconcernin

7、gpreheatandwelded,thebeneficialeffectsoftheheattreatmentcoolingratesafterwelding.Grayironcontainsaredestroyedinthevicinityoftheweldbytheconsiderablefreegraphite,whichgivesbrokensurfacesrapidchillingfromtheweldingtemperature.Theacharacteristicgraycolor.Combinedcarboningrayfusionzoner

8、evertsbacktochilled