激光熔覆新型Co基合金组织及擦性能研究 5

激光熔覆新型Co基合金组织及擦伤性能研究Studyof

MicrostructureandAbrasionResistanceofNovelCo-BasedAlloyLaserCladdingCoatings

答辩人：任方成Candidate:RenFangcheng导师：姚建华教授Advisor:Prof.YaoJianhua时间：2015.5.26

激光先进制造研究院目录(contents)1研究背景及意义(Backgroundandsignificance)2Co基合金熔覆工艺与组织研究(Microstructure)Co基合金熔覆层的性能分析(Performance)3阀门密封面应用研究(Application)4结论与展望(Conclusionsandprospects)5一研究背景及意义(Backgroundandsignificance)煤制油化工阀门工况要求(Coalliquefactionprocess)直接液化Directliquefaction间接液化Indirectliquefaction①430~470℃②17~30MPa①350℃②2-3MPa④由H2S,NH3,H2,CO,O2,Cl-等腐蚀性物质引起的腐蚀(Corrosion)⑤流体介质中大量硬质颗粒造成的磨损、(Wear,abrasioncausedbymassivehardparticlesfromliquidphase)擦伤失效Failure③冲蚀，气蚀(Erosion,cavitation)擦伤HVOF工艺表面堆焊工艺(Welding)ENP(化学镀镍磷合金)工艺优点：效率高，得到高性能涂层(Advantages:Highefficiency)缺点：涂层结合力弱，涂层薄(Disadvantages:Lowbondingstrength)优点：经济性好，技术门槛低(Advantages:Higheconomicefficiency)缺点：稀释率大，热影响区大(Disadvantages:Higherdilutionrate)优点：大批量生产，涂层性能稳定均匀(Advantages:Uniformproperties)缺点：涂层薄，结合力较弱(Disadvantages:Thincoating,lowbondingstrength)

相比以上工艺，激光熔覆技术具有涂层结合力强，涂层厚度可控，稀释率小，热影响区小。(Strongbonding,lowerdilutionrate,adjustablecoatingthickness)激光熔覆工艺(lasercladding)存在问题：高硬度、耐磨损、耐腐蚀合金粉末大面积应用易出现裂纹，孔洞等缺陷。(Problems:Crackinginthehighhardnesscoatings)优点(Advantage)：一研究背景及意义(Backgroundandsignificance)一研究背景及意义(Backgroundandsignificance)激光熔覆Co合金粉末沿用热喷涂粉末，主要类型有：Thermalspraypowder:研发成本低，且大面积应用时无裂纹、内部缺陷出现的高性能激光熔覆用粉末是激光熔覆材料技术的难点。Challengeoflasercladding:Nocrackinginlarge-areacoatingsandlowR&DcostsCo基自熔性合金粉末(Co-basedselffluxingalloy)金属基/陶瓷复合粉末(Compositepowderofceramicsandmetal)Co基非自熔性合金粉末(Co-basednonselffluxingalloy)粉末研发成本高；高性能涂层易出现开裂、表面或内部缺陷问题。(HighcostsinR&D;Crackingfoundincoatings)成型能力、造渣能力及对熔池的保护差。(Poorweldpoolprotection)硬质颗粒在润湿性、稳定性及热膨胀系数方面的不同导致力学性能不均匀。(Non-homogenousmechanicalpropertiescausedbydifferentcoefficientsofthermalexpansion)一研究背景及意义(Backgroundandsignificance)课题的意义和创新点(Significance

and

innovation)获得了熔覆层在碳含量降低与Mo元素增加后的组织与耐磨性的变化规律；制备新型Co基高性能激光熔覆层克服了高硬度Co基合金大面积应用时易裂的技术瓶颈。(DevelopmentofnovellasercladdingStellitealloypowderwith70wt%high-carbonStellitealloyplus30wt%lowcarbonStellitealloytoreducecrackinginthecoatinglayer.)采用自动划痕仪进行单点划痕模拟避免了传统阀门擦伤试验必须在进行实体阀门开关闭测试的限制。对划痕深度、加工硬化特性，切向力与划痕形貌进行了分析。(Thisnovelcoatinghasbeenappliedonthesealingsurfaceofballvalvesandbutterflyvalves.Theperformanceofthecoatingisinvestigatedunderworkhardeningtest.)激光熔覆专用合金粉末的调配(Specialpowderpreparation)优化工艺参数：1不同粉末配比2工艺与涂层硬度3金相组织(Processparameteroptimization)单道多道搭接试验、制备试样。进行组织物相与性能的分析(Performanceanalysis)球阀、蝶阀实体熔覆与擦伤泄露测试。(Valvesealingsurfacelasercladding)本文的工作内容(Workcontents)

二Co基合金熔覆工艺与组织研究(Microstructure)煤制油阀门密封面工况特殊要求(Coalliquefactionprocess)需具有抗冲蚀、抗气蚀与抗擦伤的能力(Erosion,cavitationandabrasionreisitance)抗H+、H2S、Cl-腐蚀的能力(CorrosioncausedbyH+,H2S,Cl-)粉末的调配(Powderpreparation)numbermaterialsability1Co-Cr-Walloyexcellent217-4PHor17-7PHgood3SA182-F316orSA182-F316Lgood4Cr-Mosteelcommon5Castironcommon(Strongcarbide-formingelements)结合力强弱：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.合金的选择(Selectionofalloy)：1、Co基合金

(Co-basedalloy)2、合金中需含有足够的强化相（碳化物等）阻止擦伤

(Enoughstrengtheningphasetopreventabrasion)Stellite3Co-Cr-WHighercarboncontent,higherhardnessWearandabrasionresistanceStellite21Co-Cr-MoLowercarboncontent,lowerhardness,betterworkhardeningRelativelylowwearresistanceNewalloyCo-Cr-W-MoGoodMacroscopicfeatureWearandabrasionresistanceHighhardness,workhardening二Co基合金熔覆工艺与组织研究(Microstructure)Crackoccursinlasercladdingcoatings3、合金中需要强碳化物形成元素W、Cr去防止氢腐蚀的发生；Mo元素可以与S形成弥散析出物，削弱H2S腐蚀

（ThenewalloyneedscontainingW、MoandCrelement）Nocrackformationinlasercladdingcoatings序号Stellite3Co-1Co-2Co-3层高层高层高层高1#4454755125362#4824685235323#4734955185504#7127397257935#7487747918206#7978108339207#1047116312201254编号功率kW扫描速度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)激光工艺优化(Laserprocessoptimization)Stellite3Stellite3:Stellite21=9:1(wt%)(Co-1)Stellite3:Stellite21=8:2(wt%)(Co-2)Stellite3Co-3Co-2Co-17#1#(Coatinglayerheight)单层高度测试(μm)(Hardnesstest)硬度测试二Co基合金熔覆工艺与组织研究(Microstructure)Stellite3Co-1Co-3Co-23#熔覆层6#熔覆层6#熔覆层3#熔覆层(Dilutionrate)稀释率：55.1%(Dilutionrate)稀释率：32%(Dilutionrate)稀释率：33%(Dilutionrate)稀释率：42%(Layerheight)高度：473μm(Layerheight)高度：495μm(Layerheight)高度：833μm(Layerheight)高度：920μmStellite21的逐渐增多(AdditionofStellite21)新合金中B、Si含量减少，熔点升高(DecreaseofB,Sicontent)熔池流动性变差、黏度增大，熔融状态不易外流(Liquidityvariation)稀释率更小(Lowerdilutionrate)Stellite3Co-1Co-2Co-3优化的参数:(Optimalparameters)：Co-3合金(Stellite3:Stellite21=7:3)(wt%)6#

(功率:1600W,送粉量:13g/min,扫描速度:6mm/s)二Co基合金熔覆工艺与组织研究(Microstructure)层高更高(Thickerlayer)激光工艺优化(Laserprocessoptimization)较大面积的搭接试验(largeoverlapingtest)涂层显微组织分析（Microstructureanalysis）Stellite3Co-3Co-2Co-1Stellite21的加入(AdditionofStellite21)新合金组织粗大(Coarsegrains)新合金中W含量减少,Mo含量增加(Wcontentdecreases,Mocontentincreases)W元素细化晶粒的能力强于Mo元素(WelementisbetterthanMoelementintheabilityofgrainrefinement)Co-3合金面扫秒分析(MapanalysisofCo-3)AreaCCrWMoFeCo15.2319.6120.975.806.35Bal.24.9625.3615.744.287.39Bal.39.2535.999.192.596.41Bal.123二Co基合金熔覆工艺与组织研究(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较高的W、Mo含量更容易形成(Co,W)6C,Co7Mo6(HigherW

andMocontentiseasiertoform(Co,W)6C,Co7Mo6)相反的，较低的W、Mo含量更容易形成(Co,W)3C,Co3Mo(LowerWandMocontenteasilyforms(Co,W)3CandCo3Mo)二Co基合金熔覆工艺与组织研究(Microstructure)三Co基合金熔覆层性能分析(Performance)摩擦磨损性能分析(Wearperformanceinvestigation)Stellite3Stellite21Co-3三种合金磨损体积(wearloss)摩擦系数曲线(Frictioncoefficientcurves)Stellite3Co-3Stellite21三Co基合金熔覆层性能分析(Performance)摩擦磨损性能分析(Wearsurfaceanalysis)添加了Stellite21的Co-3合金中，Co3Mo阻碍磨损的作用与(Co,W)3C相似Co3Mophaseh