双相不锈钢

SandvikMaterialsTechnologyPh.DJan-OlofNilsson尼尔森博士国际知名双相钢物理冶金专家山特维克研发中心物理冶金室主任瑞典哥德堡科技大学教授博士生导师长期从事双相钢的研究工作已发表论文120余篇SandvikMaterialsTechnologyDuplexStainlessSteels--AHappyMarriagebetweenAusteniteandFerrite双相不锈钢--奥氏体和铁素体的完美结合Ph.DJan-OlofNilssonSandvikMaterialsTechnology瑞典山特维克材料技术公司SandvikMaterialsTechnologyDSSconsistof2phases双相钢的两相组成Ferrite铁素体Austenite奥氏体20mmDuplexisLatinandmeans2-foldDuplex源自拉丁语“两相”SandvikMaterialsTechnologyApplications:应用Oil&Gasindustryandotherapplicationswheretherearechlorideionspresent石油和天然气工业氯离子存在的领域Pittingresistanceisofcrucialimportanceincombinationwithstrength,weldability,toughnessandprice.抗点蚀性能至关重要,强度,可焊性,韧性和价格都有优势SandvikMaterialsTechnologyExample:UmbilicalsintheOilandGasIndustry多芯管在石油和天然气工业中的应用实例SandvikMaterialsTechnologyThecustomerworriesmainlyaboutthemacroscopicproperties用户主要担心宏观性能Theproducercontrolsthefinalpropertiesbymicrostructuralengineering生产商用微观组织工程控制最终性能SandvikMaterialsTechnologyDuplexStainlessSteelHistoryI双相钢的历史I•In1927thefirstduplexstainlesssteel(DSS)wasdescribed(BainandGriffiths)1927Bain和Griffiths首次提出双相钢•Increasedinterestafterthe2ndworldwarduetotheshortageofnickel二战后由于镍的短缺,双相钢开始引起兴趣•DSSgainedabadreputationduetopoorunderstandingofitsweldability由于可焊性的问题,双相钢的声誉并不好–HighferritecontentsresultedinalmostfullyferriticHAZ热影响区几乎全是铁素体–Lowcorrosionresistance抗腐蚀性低–Poormechanicalproperties机械性能差SandvikMaterialsTechnologyDuplexStainlessSteelHistoryII双相钢的历史II•Inthe50’sprogresswasmade&hencebetterunderstandingforDSS’performancewasachieved五十年代开始,对双相钢的认识提高–ModernDSShaveoptimizedferrite-austeniteratio(~50%;~50%)优化铁素体-奥氏体的比率(50:50)–Alloyingwithnitrogen(N)加入合金元素氮–BetterweldabilityduetohigherN-andlessC-contents提高可焊性,高氮低碳SandvikMaterialsTechnologySandvikAusteniticFerriticGradesSAF山特维克双相钢级别•3RE60–DevelopedbySandvikinthe1960’s开发于六十年代•SAF2205(UNSS31803)–Sandvikgainedexperienceduringextensiveworkwiththealloy山特维克经过大量工作后得出的经验•SAF2304(UNSS32304)–DevelopedbySandvikasaleanDSSinthe1980’s节约型双相钢开发于八十年代–LowalloyDSSdevelopedasanalternativetoAISI316L低合金双相钢用于替代316L•SAF2507(UNSS32750)–DevelopedbySandvikinthe1980’s(optimizedbyT-C)开发于八十年代(计算机优化)–SuperDuplexStainlessSteel(SDSS)originallydevelopedtoresistseawatercorrosion超级双相钢最初是为抗海水腐蚀开发SandvikMaterialsTechnologyChemicalComposition化学成分SandvikUNSCmaxSimaxPmaxSmaxMnCrNiMoNSAF2304SAF2205SAF2507NEW????S32304S31803S327500,030,030,031,01,00,80,0350,0300,0350,0150,0150,0152,02,01,22322254,557-3,240,10,180,3SandvikMaterialsTechnologyAhappymarriagebetweenausteniteandferrite奥氏体和铁素体的完美结合•Anunusualcombinationofproperties不同寻常的性能组合•Advantages:优点Highstrength,goodtoughness,corrosionresistance(stresscorrosion,pittingcorrosion),weldability,price(lowconcentrationofNi),machinabilityandproduceability.高强度,优韧性,抗应力腐蚀,抗点蚀,可焊性,机械性,价格,加工性•Drawbacks:缺点475°C-embrittlement,pronetoformingintermetallicphasesintherange600-900°C.475度脆变,在600-900度之间会形成金属间相SandvikMaterialsTechnologySandvikYieldTensileElongHardnessGradeStrengthStrengthARockwellC(Vickers)0.2%offset%MPaminMPaminSAF2507550800-10002529(290)SAF2205450680-8802524(260)SAF2304400600-8202518(230)Theyieldstrengthcanbefurtherincreasedbyapproximately400MPaifthematerialiscoldworkedinapilgeringoperation.材料经皮尔格冷加工后屈服强度会增加约400MPaMechanicalproperties机械性能Minimumvaluesforwallthickness20mm壁厚小于20mm的最小值SandvikMaterialsTechnologyYieldStrengthRp0,2[MPa]ComparisonbetweenAusteniticandDuplexStainlessSteels奥氏体钢和双相钢屈服强度的比较316L904L6Mo+NSAF2304SAF2205SAF25070100200300400500600SandvikMaterialsTechnologyDSS-StrengtheningMechanisms双相钢的强化机理Generally,duplexstainlesssteelshavehigheryieldstrengththanausteniticstainlesssteelsowingto:双相钢比奥氏体钢有较高的屈服强度是因为:Presenceofferrite存在铁素体Nitrogen(upto0.4%)氮(可达0.4%)SmallerGrainSize(~10mm)晶粒度更细(约10mm)SandvikMaterialsTechnologyVarioustypesofwetcorrosion不同类型的湿法腐蚀•Generalcorrosion均匀腐蚀•Pittingcorrosion(timetofailure1-7days)点蚀(1-7天失效)•Crevicecorrosion缝隙腐蚀•Stresscorrosion(timetofailure~1h)应力腐蚀(1小时失效)•Microbiologicallyinfluencedcorrosion(MIC)微生物腐蚀Pittingcorrosionisperhapsthemostimportantoneasitmayleadtoothertypesofcorrosion!其中点蚀的危害最大,因为这会引起其他形式的腐蚀!SandvikMaterialsTechnologyResistancetopittingisdependentoncomposition!抗点蚀性能取决于成份!PRE=%Cr+3.3%(Mo+0.5W)+16%NPREgivesinformationonresistancetolocalisedcorrosioninchloridecontainingenvironmentsPRE提供了在氯离子环境中抗局部腐蚀的信息Pittingresistanceisassessedinferricchloridesolution,ASTMG48A抗点蚀性能可按ASTMG48A进行评估ItisempiricallyfoundthatthereisalinearrelationbetweenthePREandpittingcorrosionresistance经验得出PRE和抗点蚀性有线性关系Drawbacks:Cr,MoandNallhaveside-effects缺点:铬,钼和氮有副作用SandvikMaterialsTechnologyPREvsCPT抗点蚀当量与临界点蚀温度203040506070809030354045SAF250725Cr,DSSSAF2205254SMOSanicro28904L,20-25+Mo,CuPRE=%Cr+3.3%(Mo+0.5W)+16%N抗点蚀当量SandvikMaterialsTechnologyNi,NCr,MoAlloyingelementsarepartitionedbetweenand合金元素也分两相Cross-overTisdependentoncomposition临界温度取决于成分PRE-balancebetweenandiscrucial!相的平衡对PRE至关重要SandvikMaterialsTechnologyTheeffectoftestingaccordingto按ASTMG48A,24hat80°C的实验效果316904L230422052507IncreasingresistancetopittingowingtohigherPREvalue随着PRE值的提高,抗点蚀能力相应提高SandvikMaterialsTechnologyComputedisoplethdiagramfor29Cr-7Ni-2MoDSS2