简介:Inthisstudy,aroll-bondedUNSN088225alloycladpipelinesteelwasinvestigatedanddevelopedinBaosteel.Basedontherequirementsofanumberofpotentialprojects,weperformedaseriesofstrictevaluationsincludingmechanicalandcorrosiontests.Theresultsshowthemechanicalpropertiesandcorrosionresistanceofthiscladsteeltobeexcellentandtomeettherequirementsofallthedesignparameters.
简介:ThecausestotheoutersurfacefoldingdefectsinN80-Qoilcountrytubulargoods(OCTG)wereinvestigatedthroughtheobservationofthedefects’morphology,microstructureandtheanalysisofthechemicalcompositions.Itisbelievedthatthedefectwasresultedfromtheintrinsicflawsthatoriginallyexistedonthebillet;theywereextendedandoxidizedduringthefollowingreheatingandrollingprocesses.Withmorestrictqualitycontrolandinspectionofthebillet,thedefectcanbepreventedeffectivelyfromoccurring.
简介:TheFe-Ti-Nmateralloywaspreparedthroughthein-situreactionofnitrogengaswiththeFe-Timelt.ScanningelectronmicroscoperesultsshowthattheparticlesuniformlydistributedintheironmatrixwereTiN.ThedeliberatelypreparedFe-Ti-Nmasteralloywasemployedforthe409Lferriticstainlesssteelinanattempttorefinetheas-castsolidificationstructure.ItwasfoundthattheeffectivenessofFe-Ti-Nmasteralloyonrefiningoftheas-cast409Lferriticstainlesssteelwasaffectedbyadditionlevel,holdingtimeandmeltstemperature.Itwasfoundthattheaverageequiaxedgrainsizedecreasedfrom1503μmto303μm,theproportionofequiaxedgrainzoneincreasedfrom14%to100%withincreasingtheFe-Ti-Nmasteralloyadditionlevelto2.5%.Theproportionofequiaxedgraindecreasedfrom85%to4%asthesolidificationtemperatureincreasedfrom1803Kto1883K.Whentheholdingtimereachedto8min,thesolidificationstructuresof409Lferriticstainlesssteelshowextremepointsintheproportionofequiaxedgrain.Itisclearthatthegrainrefiningefficiencygraduallyfadeawaywiththeincreasingoftheholdingtimeattheverybeginning.However,whentheholdingtimecontinuestoincreaseandexceedstheextremepoint,thegrainrefiningefficiencyoftheFe-Ti-Nmasteralloyrecoveredtoacertaindegree.Theexperimentalresultsmentionedabovehavebeenanalyzedintermsofthermodynamics.Underappropriateconditions,theFe-Ti-Nmasteralloyusedforgrainrefinementofthesolidificationstructureof409Lferriticstainlesssteelmayhavegoodprospectsforindustrialapplications.