简介:Thisstudyexploresreasonsfortherandomoccurrenceofstampingcracksduringtheproductionofpureironmagneticshieldingcovers.Scanningelectronmicroscopyandenergyspectrumareusedtoobservecrackswithinparts,andresultsshowsignificantbrittlefracturemorphologywithchunksofmanganesesilicateandaluminumsilicateinclusionspresentinthefracturesurface.Thechemicalcomposition,mechanicalproperties,andmicrostructurearealsoanalyzedforacorrespondingbatchofcoldrolledpureironsheet.Theoxygencontentofthematerialisfoundtobehigh,resultingintherandomdistributionofalargeamountoflongchainmanganesesilicateandaluminumsilicateinclusionsalongtherollingdirection,whichcorrespondstoinclusionsfoundonthefracturedsurface.Thestampingcracksarethusassumedtobecausedbytherandomlydistributedchainofinclusionswithinthecoldrolledsheet.Itissuggestedthattheamountofdeoxidizerusedshouldbemorecarefullycontrolledtodecreasetheinclusioncontentsandtothusavoidtherecurrenceofsuchdefects.
简介:Cold-rolledhighstrengthsteelsheetsforautomobilescontainmoreMnandSibasedalloyelements,which,underthereducingatmosphereintheannealingfurnace,willgetenrichedonthestripsurface.Sincethefurnacerollersandthestripscontactfrequently,alloyelementsontherollersurfacewillformhardprotuberance.Wecallthisprotuberance"pick-up".Inaddition,withtheincreaseoftheamountofdustinthefurnaceatmosphere,theoccurrenceoffurnacerollerpick-upwillalsoincrease.Throughchemicalreactionandphysicalaccumulationanalysiscombinedwithpracticalexperience,thecausesofpick-upindifferentfurnacesectionswereanalyzed.Methodsofpreventingfurnacerollerpick-upinthehighstrengthsteelsheetprocessinglinewerediscussedandsolutionstoimprovingthestripsurfacequalityinthecontinousannealingfurnacewereprovided.