简介：TheSteelAISI4145HMforseniorpetroleumdrillofBXSteelwasproducedbythefollowsheet:hotmetalpretreatment→converter→LF→RH→caster350mm×470mmrectangularbillet→hotdelivery→reheating→800millrolling→insulation→straightening→anneal→grinding→inspection→packagingandpayintotreasury→shipment.SelectedBXSteelparticularhormetal,adoptedhotmetaldesulphurizationpretreatmenttechnology.TheLFrefiningmakingthewhiteslag,andkeepacertaintime.TheRHtreatmentmustmakesurethevacuumdegreeandrefiningtime,moreimportantlycontrollingargonblowingprocess.Inaddition,mustdesignpropertechnologydatacontinuouscastingsimilarsuperheat,castingspeed,andspecificwaterflowrate.Dependontechnologicalmeasures,theproductbeenhadseriesofthequalities:homogeneityofchemicalcomposition,lowcontentofharmfulelements,highpurity,compactorganization.Adoptedtheprocessofcastingbillethotdeliveryandhotcharging,usedsteppingheatingfurnace,anddesigningreasonablethermalparameters.Two-highreversingmillroughrollspreparationsquarebillet,short-stress-pathrollingmillrollsroundbar.Steelproductsbadholdingandcontrollingsoakingtimeandtemperature.Steelproductsbadannealed,andannealingprocessmustbeencontrolledforensuringsteelhardnessuniform.Foravoidingresidualstress,steelbeenstraightenedbeforeanneal.Thetestresultsandusingeffectshowsthattheproducingwithuniformannealinghardnessandniceprocessingproperties,niceoverallmechanicalproperties,wererecognizedbyusers.

简介：ThepapershowsthemainsurfacedefectsofcoldrollingautomobilesheetinBXSteel.Themainsurfacedefectsareunusualdefects.Thetypicalfamiliardefectsaresliverandpunctuatesthatareontherollingdirection.Theinclusionsofsteel-makingandscalesofhotrollingprocessarethemaincausesofdefects.Theyarethebiggestproblemspuzzlecoldrolledautomobilesheetsurfacequality,andaretheburningissuesofBXSteel.Weclassifyandanalysisthedefects.Weobservethepanoramaofsurfacedefectsusingportablevideomicroscopyapparatus,andcleanthesampleusingultrasonicshaker,analysisthedefectspatternandchemicalcompositionusingscanningelectronmicroscope.Atpresenttheprimarydefectsthatimpactedcoldrolledautomobilesheetqualityaredarksliverdefects.Wecontrolthesteel-makingandhotrollingprocessaimingatthecauseandpositionofdefectsmaking.Wefinecontroltheoperatingofsteelladle,gating,castingsystemandcontinuouscastingmachineinsteelmakingprocess.Thescaledefectisreducedbycontrollingfurnace,highpressurewaterdescalingsystemandfinishmilldescalinginhotrollingprocess.Alonewiththereformingandrenewingofequipment,gatheringproducingexperience,thecoldrolledautomobilesheetqualitymadeinBXSteelisupgradinggradually.