简介:BasedonAPISTD1104-2005andCSAZ662-2007,fieldgirthweldingtestsandgirthweldabilityevaluationswereexecutedforthreetypesofwallthicknessX70UOEpipeline,inwhichthemostpopularmainlinegirthweldingmethod,single-wireautomaticgasmetalarcwelding(GMAW),wasused.Theweldingprocedurespecificationwasoptimizedtoachieveagoodqualityandcold-crack-freegirthweldjointwithoutpreheatingorpost-weldheattreatment.Inaddition,porosities,inclusions,andincompletefusiondefectswereavoided.Thetensilestrength,bending,Vickershardness,CharpyV-notchimpacttoughness,andcracktipopeningdisplacementfracturetoughnessofthegirthweldjointwereevaluated,andthejointexhibitedgoodmechanicalperformance.Thus,thefieldgirthweldabilityofBaosteel’sX70UOEpipelineisexcellentforautomaticGMAW.
简介:Inordertostudythestresscorrosioncracking(SCC)ofX70pipelinesteelanditsweldjointinacidsoilenvironmentofsoutheastofChina,twosimulatingmethodswereusedhere.Theonewastoobtainthebadmicrostructuresinheataffectedzonebyannealingat1300°Cfor10minandaircoolingtoroomtemperature,theotherwastogetaseriesofsimulatingsolutionsoftheacidsoilenvironment.SCCsusceptibilitiesofX70pipelinesteelsbeforeandafterbeingnormalizedinthesimulatedsolutionswerestudiedbyslowstrainratetest(SSRT)andmicrostructuralobservationoffractureareas.Potentiodynamicpolarizationcurveswereusedtostudytheelectrochemicalbehaviourofdifferentmicrostructures.SCCdoesoccurtoboththeas-receivedmaterialandnormalizedmicrostructureafterheattreatmentasthepolarizationpotentialdecreased.Hydrogenembrittlement(HE)isindicatedoccurringtoalltestedmaterialsat-850mV(vsSCE)and-1200mV(vsSCE).TheSCCmechanismsaredifferentwithinvaryingpotentialrange.Anodicdissolutionisthekeycauseaspolarizationpotentialhigherthannullcurrentpotential,andHEwillplayamoreimportantroleaspolarizationpotentiallowerthanthenullcurrentpotential.
简介:Separationisacommonlyobservedphenomenonduringdropweightteartestinginhigh-toughnesslinepipesteels.Severeseparationisharmfulbecauseitmaycausefracturingorburstingofpipes.Inthisstudy,aquantitativemeasurementofseparationwasproposed,andusingthisnewmethod,arelationshipbetweentheseparationandmicrostructurewasdeterminedanddiscussed.Themicrostructuresobservedusingopticalandscanningelectronmicroscopyrevealedthattheseparationwasrelatedtothemixedferriticandbainiticmicrostructures,orrather,itwasrelatedtothecarbonenrichmentinbainite.
简介:BaoshanIron&SteelCo.,Ltd.,(referredtoasBaosteel)inChinafirstsucceededindevelopingtheU-ing-O-ing-Expanding(UOE)longitudinalsubmergedarcweldedpipes(SAWLs)offshorelinepipeofamaximumthickness/outsidediameter(T/D)0.042in2011.DescribedinthispaperistheresearchanddevelopmentoftheX70UOESAWLpipesbythecompany.TheresultshowsthatthesaidX70linepipehasbeenincompliancewithrelevantrequirementsasspecifiedinSpecificationsDNV-OS-F101,andhasbeensuccessfullyusedintheSouthChinaSeadeepwatergaspipelineproject.
简介:摘要:目前国内厚规格管线钢生产过程趋于稳定,但管线钢低温卷取温度控制稳定性仍是热轧产线控制难点。湛江2250热轧生产厚规格管线钢,层冷模型控制精度低、带钢尾部速度异常、水温补偿不合理是导致管线钢卷取温度精度异常的主要原因。通过对模型学习、反馈区水控制、速度控制、工艺参数、水温补偿等进行优化后,厚规格管线钢卷取温度控制精度、模型自动控制水平均大幅度提高。
简介:本文采用扫描振动微电极和局部电化学交流阻抗谱测试了近中性pH环境中X70管线钢平滑试样及裂纹尖端发生的局部溶解电化学行为,用来确定并量化应力和氢以及它们对阳极溶解的协同作用在裂纹扩展中的作用。研究结果表明,外加拉伸应力能够提高管线钢的阳极溶解速度,应力较小时,应力加速溶解并不明显;应力提高到80%屈服强度时,管线钢的阳极溶解速度显著提升。裂纹或者裂纹状缺陷的存在会引起应力集中因而会导致加速局部阳极溶解速度。当预制裂纹CT试样受到3000N拉力时,裂尖的应力影响阳极溶解因子高达3.6,而低应力区域只有1.10。近中性pH环境中氢与应力对管线钢在的阳极溶解的联合作用,这对裂纹的扩展起到了决定性的作用。受到525MPa应力的平滑试样在不同电流密度0.1mA/cm^2,1mA/cm^2,5mA/cm^2,10mA/cm^2和20mA/cm^2充氢后,氢与应力对阳极溶解的协同影响因子,分别是1.048,1.668,2.568,3.976和5.437。
简介:摘要:X70型集装箱专用平车检修过程中发现了大量储风缸吊裂损情况,本文对该车储风缸吊裂损故障处理提出了相应的解决方案和预防措施。