激光熔覆新型Co基合金組織及擦性能研究 5

激光熔覆新型Co基合金組織及擦傷性能研究Studyof

MicrostructureandAbrasionResistanceofNovelCo-BasedAlloyLaserCladdingCoatings

答辯人：任方成Candidate:RenFangcheng導師：姚建華教授Advisor:Prof.YaoJianhua時間：2015.5.26

激光先進制造研究院目錄(contents)1研究背景及意義(Backgroundandsignificance)2Co基合金熔覆工藝與組織研究(Microstructure)Co基合金熔覆層的性能分析(Performance)3閥門密封面應用研究(Application)4結論與展望(Conclusionsandprospects)5一研究背景及意義(Backgroundandsignificance)煤制油化工閥門工況要求(Coalliquefactionprocess)直接液化Directliquefaction間接液化Indirectliquefaction①430~470℃②17~30MPa①350℃②2-3MPa④由H2S,NH3,H2,CO,O2,Cl-等腐蝕性物質引起的腐蝕(Corrosion)⑤流體介質中大量硬質顆粒造成的磨損、(Wear,abrasioncausedbymassivehardparticlesfromliquidphase)擦傷失效Failure③沖蝕，氣蝕(Erosion,cavitation)擦傷HVOF工藝表面堆焊工藝(Welding)ENP(化學鍍鎳磷合金)工藝優(yōu)點：效率高，得到高性能涂層(Advantages:Highefficiency)缺點：涂層結合力弱，涂層薄(Disadvantages:Lowbondingstrength)優(yōu)點：經濟性好，技術門檻低(Advantages:Higheconomicefficiency)缺點：稀釋率大，熱影響區(qū)大(Disadvantages:Higherdilutionrate)優(yōu)點：大批量生產，涂層性能穩(wěn)定均勻(Advantages:Uniformproperties)缺點：涂層薄，結合力較弱(Disadvantages:Thincoating,lowbondingstrength)

相比以上工藝，激光熔覆技術具有涂層結合力強，涂層厚度可控，稀釋率小，熱影響區(qū)小。(Strongbonding,lowerdilutionrate,adjustablecoatingthickness)激光熔覆工藝(lasercladding)存在問題：高硬度、耐磨損、耐腐蝕合金粉末大面積應用易出現裂紋，孔洞等缺陷。(Problems:Crackinginthehighhardnesscoatings)優(yōu)點(Advantage)：一研究背景及意義(Backgroundandsignificance)一研究背景及意義(Backgroundandsignificance)激光熔覆Co合金粉末沿用熱噴涂粉末，主要類型有：Thermalspraypowder:研發(fā)成本低，且大面積應用時無裂紋、內部缺陷出現的高性能激光熔覆用粉末是激光熔覆材料技術的難點。Challengeoflasercladding:Nocrackinginlarge-areacoatingsandlowR&DcostsCo基自熔性合金粉末(Co-basedselffluxingalloy)金屬基/陶瓷復合粉末(Compositepowderofceramicsandmetal)Co基非自熔性合金粉末(Co-basednonselffluxingalloy)粉末研發(fā)成本高；高性能涂層易出現開裂、表面或內部缺陷問題。(HighcostsinR&D;Crackingfoundincoatings)成型能力、造渣能力及對熔池的保護差。(Poorweldpoolprotection)硬質顆粒在潤濕性、穩(wěn)定性及熱膨脹系數方面的不同導致力學性能不均勻。(Non-homogenousmechanicalpropertiescausedbydifferentcoefficientsofthermalexpansion)一研究背景及意義(Backgroundandsignificance)課題的意義和創(chuàng)新點(Significance

and

innovation)獲得了熔覆層在碳含量降低與Mo元素增加后的組織與耐磨性的變化規(guī)律；制備新型Co基高性能激光熔覆層克服了高硬度Co基合金大面積應用時易裂的技術瓶頸。(DevelopmentofnovellasercladdingStellitealloypowderwith70wt%high-carbonStellitealloyplus30wt%lowcarbonStellitealloytoreducecrackinginthecoatinglayer.)采用自動劃痕儀進行單點劃痕模擬避免了傳統(tǒng)閥門擦傷試驗必須在進行實體閥門開關閉測試的限制。對劃痕深度、加工硬化特性，切向力與劃痕形貌進行了分析。(Thisnovelcoatinghasbeenappliedonthesealingsurfaceofballvalvesandbutterflyvalves.Theperformanceofthecoatingisinvestigatedunderworkhardeningtest.)激光熔覆專用合金粉末的調配(Specialpowderpreparation)優(yōu)化工藝參數：1不同粉末配比2工藝與涂層硬度3金相組織(Processparameteroptimization)單道多道搭接試驗、制備試樣。進行組織物相與性能的分析(Performanceanalysis)球閥、蝶閥實體熔覆與擦傷泄露測試。(Valvesealingsurfacelasercladding)本文的工作內容(Workcontents)

二Co基合金熔覆工藝與組織研究(Microstructure)煤制油閥門密封面工況特殊要求(Coalliquefactionprocess)需具有抗沖蝕、抗氣蝕與抗擦傷的能力(Erosion,cavitationandabrasionreisitance)抗H+、H2S、Cl-腐蝕的能力(CorrosioncausedbyH+,H2S,Cl-)粉末的調配(Powderpreparation)numbermaterialsability1Co-Cr-Walloyexcellent217-4PHor17-7PHgood3SA182-F316orSA182-F316Lgood4Cr-Mosteelcommon5Castironcommon(Strongcarbide-formingelements)結合力強弱：Fe＜Mn＜Cr＜Mo＜WMo+Sprecipitation

AlloyCrWMoCFeNiSiMnHRCapplicationStellite330.512.5

-2.453.52260Valveseatetc.Stellite4301410.57332141Hotembossingmouldetc.Stellite628.54.51.51532240Enginevalveetc.Stellite12308.3

-1.431.50.72.542Sawtoothetc.Stellite2127

-5.50.2532.751128Turbinebladeetc.Stellite31227.5

-0.51.5100.50.531Turbinebladeetc.Stellite8033.519

-2.0-

-

-

-

52Bearingsleeveetc.AlloyCrWMoCFeNiSiMnHRCapplicationStellite330.512.5

-2.453.52260Valveseatetc.Stellite2127

-5.50.2532.751128Turbinebladeetc.合金的選擇(Selectionofalloy)：1、Co基合金

(Co-basedalloy)2、合金中需含有足夠的強化相（碳化物等）阻止擦傷

(Enoughstrengtheningphasetopreventabrasion)Stellite3Co-Cr-WHighercarboncontent,higherhardnessWearandabrasionresistanceStellite21Co-Cr-MoLowercarboncontent,lowerhardness,betterworkhardeningRelativelylowwearresistanceNewalloyCo-Cr-W-MoGoodMacroscopicfeatureWearandabrasionresistanceHighhardness,workhardening二Co基合金熔覆工藝與組織研究(Microstructure)Crackoccursinlasercladdingcoatings3、合金中需要強碳化物形成元素W、Cr去防止氫腐蝕的發(fā)生；Mo元素可以與S形成彌散析出物，削弱H2S腐蝕

（ThenewalloyneedscontainingW、MoandCrelement）Nocrackformationinlasercladdingcoatings序號Stellite3Co-1Co-2Co-3層高層高層高層高1#4454755125362#4824685235323#4734955185504#7127397257935#7487747918206#7978108339207#1047116312201254編號功率kW掃描速度mm/min送粉量g/min比能kJ/cm21#0.61801052#0.8180105.833#1180106.664#1.23601355#1.4360135.836#1.6360136.667#1.8540165Stellite3:Stellite21=7:3(wt%)(Co-3)激光工藝優(yōu)化(Laserprocessoptimization)Stellite3Stellite3:Stellite21=9:1(wt%)(Co-1)Stellite3:Stellite21=8:2(wt%)(Co-2)Stellite3Co-3Co-2Co-17#1#(Coatinglayerheight)單層高度測試(μm)(Hardnesstest)硬度測試二Co基合金熔覆工藝與組織研究(Microstructure)Stellite3Co-1Co-3Co-23#熔覆層6#熔覆層6#熔覆層3#熔覆層(Dilutionrate)稀釋率：55.1%(Dilutionrate)稀釋率：32%(Dilutionrate)稀釋率：33%(Dilutionrate)稀釋率：42%(Layerheight)高度：473μm(Layerheight)高度：495μm(Layerheight)高度：833μm(Layerheight)高度：920μmStellite21的逐漸增多(AdditionofStellite21)新合金中B、Si含量減少，熔點升高(DecreaseofB,Sicontent)熔池流動性變差、黏度增大，熔融狀態(tài)不易外流(Liquidityvariation)稀釋率更小(Lowerdilutionrate)Stellite3Co-1Co-2Co-3優(yōu)化的參數:(Optimalparameters)：Co-3合金(Stellite3:Stellite21=7:3)(wt%)6#

(功率:1600W,送粉量:13g/min,掃描速度:6mm/s)二Co基合金熔覆工藝與組織研究(Microstructure)層高更高(Thickerlayer)激光工藝優(yōu)化(Laserprocessoptimization)較大面積的搭接試驗(largeoverlapingtest)涂層顯微組織分析（Microstructureanalysis）Stellite3Co-3Co-2Co-1Stellite21的加入(AdditionofStellite21)新合金組織粗大(Coarsegrains)新合金中W含量減少,Mo含量增加(Wcontentdecreases,Mocontentincreases)W元素細化晶粒的能力強于Mo元素(WelementisbetterthanMoelementintheabilityofgrainrefinement)Co-3合金面掃秒分析(MapanalysisofCo-3)AreaCCrWMoFeCo15.2319.6120.975.806.35Bal.24.9625.3615.744.287.39Bal.39.2535.999.192.596.41Bal.123二Co基合金熔覆工藝與組織研究(Microstructure)物相分析(Phaseanalysis)Stellite3Stellite21Co-3fcc-Co,(Co,W)6C,Cr7C3fcc-Co,Co7Mo6,Co3Mo,Cr23C6fcc-Co,(Co,W)3C,Co3Mo,Cr7C3,

Cr23C6Co-3合金灰色(gray):fcc-Co白色(white):(Co,W)3C,Co3Mo黑色(black):Cr7C3,

Cr23C6較高的W、Mo含量更容易形成(Co,W)6C,Co7Mo6(HigherW

andMocontentiseasiertoform(Co,W)6C,Co7Mo6)相反的，較低的W、Mo含量更容易形成(Co,W)3C,Co3Mo(LowerWandMocontenteasilyforms(Co,W)3CandCo3Mo)二Co基合金熔覆工藝與組織研究(Microstructure)三Co基合金熔覆層性能分析(Performance)摩擦磨損性能分析(Wearperformanceinvestigation)Stellite3Stellite21Co-3三種合金磨損體積(wearloss)摩擦系數曲線(Frictioncoefficientcurves)Stellite3Co-3Stellite21三Co基合金熔覆層性能分析(Performance)摩擦磨損性能分析(Wearsurfaceanalysis)添加了Stellite21的Co-3合金中，Co3Mo阻礙磨損的作用與(Co,W)3C相似Co3Mophaseh