疏浚用耐磨蚀钢耐磨蚀性能的研究

采用热处理+微合金化工艺在兼顾耐腐蚀的基础上开发了一种450HBW的高硬度耐磨蚀钢,在实验室测试了其自腐蚀电位及海水浆体中的耐磨蚀性能,并与实际疏浚条件下的磨蚀实验结果作了对比,同时分析了磨蚀失重中各磨蚀分量的比例。结果表明,Cr的加入提高了基体的自腐蚀电位,抑制了腐蚀的发生,加上实验钢磨损性能的提高,促进了耐磨蚀性能的改善,实验室所采用的旋转型磨蚀测试方法能够真实反映材料在实际疏浚中的磨蚀性能,实验钢的耐磨蚀性能达到普通疏浚管道用钢Q235B的2倍,实验结果与疏浚现场的磨蚀对比实验相一致。海水疏浚中的磨蚀失重主要是磨损引起的,占磨蚀失重的比例达68%,腐蚀失重仅占1.6%,而腐蚀与磨损的交互作用失重超过30%。所以疏浚管道用耐磨蚀钢的研制应以提高耐磨损性能为主,同时抑制腐蚀的发生。     

普碳钢在浆体输送中的磨蚀分析

利用改进的旋转型腐蚀磨损试验装置测试了Q235钢在浆体输送中的磨蚀特性,分析了不同条件下磨损、腐蚀及其交互作用所占的失重比例。试验结果表明,磨损是材料磨蚀失重的主要因素,交互作用次之,而腐蚀对交互作用有显著的影响。固体颗粒的冲击使得材料表面形成凹坑,产生微区硬化并促进裂纹的形成,同时,固体颗粒将材料向周围推移形成褶皱;而后续颗粒的冲击、刮擦和切削使得裂纹扩展,最终使得材料脱落形成磨蚀坑,而腐蚀消弱了褶皱与基体的连接,使得褶皱易于脱离,加速了材料的磨蚀失重。     

金属饰品材料的耐磨蚀性能探讨

目的检测六种常用金属饰品材料的耐磨蚀性能,对比分析饰品材料保持光亮度的能力。方法选择H70黄铜、316L不锈钢、TA2纯钛、CoCrMo合金、钨钢(WC)、TaC系硬质合金六种有代表性的饰品用金属材料,检测其化学成分、硬度及在人工汗液中的极化行为,采用人工汗液+漩涡研磨的方法检测各材质戒指试样的磨蚀失重率,采用扫描电镜观察试样磨蚀形貌。结果试验材料在人工汗液中点蚀电位由高到低的顺序为TA2CoCrMoTaC系硬质合金316L钨钢(WC)H70,初始硬度的高低顺序为H70TA2316LCoCrMoTaC系硬质合金钨钢(WC),腐蚀磨损失重率的高低顺序为H70TA2316LCoCrMoTaC系硬质合金钨钢(WC)。结论在人工汗液+漩涡研磨条件下,试样受到腐蚀与机械磨损的交互作用而失重和失去光亮度。除H70外,其余材质受到的腐蚀作用均相对较弱,机械磨损作用较强。材料表面硬度越高,抗磨损性越强,越有利于保持饰品表面的光亮度。     

核电厂海水循环泵用两种耐腐蚀涂层

自行设计了一套高流速旋转冲刷腐蚀试验装置,该装置配有灵活的攻角调节系统与转速调控系统,利用此设备对环氧树脂基体材料和聚氨酯材料的耐海水腐蚀涂层进行了耐冲刷性能的试验研究。结果发现,聚氨酯的耐杭州湾海水耐磨蚀性能优于环氧树脂基的乐泰涂层,腐蚀后表面较为光整,未出现汽蚀脱落等现象,而环氧基涂层表面出现明显的冲刷坑。     

热处理提高新型耐磨蚀材料性能的试验

本文主要进行了新型耐磨蚀材料的热处理工艺试验研究,同时,对材料在热处理后的抗拉强度、冲击韧性、硬度以及材料的腐蚀磨损性能进行了对比测试和分析。并利用金相显微镜和扫描电镜等对热处理后的材料组织进行了简单分析。材料在热处理后的磨蚀性能有了较大的提高,在现场应用中有很好的效果。     

含锑低合金马氏体钢的耐磨蚀性能

利用OM和SEM对0％Sb和0.2％Sb的两种马氏体钢的微观组织与腐蚀产物进行表征,测量其硬度和力学性能,并进行腐蚀磨损试验,研究了Sb元素的加入对试验钢耐磨蚀性能的影响。结果表明:试验钢具有高抗拉强度、高硬度及良好的低温(-20 ℃)冲击性能,分别能够达到1400 MPa、40 HRC以及45 J以上,0.2％Sb钢的耐磨蚀性更好。Sb元素的加入提高了钢在酸性高氯离子及高硫酸根离子环境中的耐蚀性,保证力学性能与硬度的同时提高了耐磨蚀性能。     

凝汽器材料的耐磨蚀性能及电化学性能

模拟电厂凝汽器工况,采用自行研制的磨蚀试验机比较了不锈钢板材304、316L、Sea-Cure、日本钛板以及管材Sea-Cure、白铜管B10、B30和产于中国、美国、日本三地的钛管的耐磨蚀性能,进行了材料的维氏(HV)硬度分析和磨蚀腐蚀电化学试验。结果表明,各板材的耐磨蚀性能依次为Sea-Cure日本Ti304316L,管材为Sea-Cure中国Ti美国Ti日本TiB30B10,且国内外不同产地钛管的耐磨蚀性能稍有差异。材料的耐磨蚀性能主要由基底金属硬度与钝化膜修复能力决定,硬度对应于机械冲刷作用,钝化膜则对应于腐蚀作用。建议在含砂量较高的沿海电厂凝汽器可优先选用耐磨蚀性能更佳的Sea-Cure管代替钛管作为冷却管。     

矿山湿磨衬板用耐磨蚀合金铸钢研究与应用现状

矿山用球磨机的工况条件复杂恶劣,湿磨衬板消耗巨大,研究开发矿山湿磨衬板和耐磨蚀合金钢具有重要的工程价值.论文对目前国内矿山湿磨衬板使用的耐磨蚀合金钢进行分类,评述了不同工况下矿山湿磨衬板用耐磨蚀合金钢的性能及优缺点,展望了矿山湿磨衬板用耐磨蚀合金钢的发展趋势.指出了未来该领域工作的重点和方向是,深入开展冲击腐蚀磨料磨损机理研究;优化耐磨蚀钢合金成分设计,进一步提高耐磨蚀合金钢的耐磨蚀性能,重视矿山湿磨衬板大型化趋势;根据矿山湿磨工况复杂和差异化情况研发和选用耐磨蚀合金钢及其衬板.     

腐蚀磨损金属学及耐磨蚀合金初探

腐蚀磨损金属学及耐磨蚀合金初探路新春(中国科学院金属研究所九四级博士研究生,沈阳110015)本文对不锈钢腐蚀磨损中的几个金属学问题进行了研究,重点探讨了发展耐磨蚀合金的途径.首先对实际生产中国磨蚀而报废的磷酸料浆泵叶轮进行了失效分析,确认其失效原因是磨损(冲蚀)和腐蚀与磨损的交互作用,并对延长其使用寿命提出合理建议.试车结果表明,结论正确,建议合理.研制和改进了4台腐蚀磨损试验设备:稳态、暂态、往复式及料浆冲蚀....     

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利用改进的旋转型腐蚀磨损试验装置测试了Q235钢在浆体输送中的磨蚀特性,分析了不同条件下磨损、腐蚀及其交互作用所占的失重比例。试验结果表明,磨损是材料磨蚀失重的主要因素,交互作用次之,而腐蚀对交互作用有显著的影响。固体颗粒的冲击使得材料表面形成凹坑,产生微区硬化并促进裂纹的形成,同时,固体颗粒将材料向周围推移形成褶皱;而后续颗粒的冲击、刮擦和切削使得裂纹扩展,最终使得材料脱落形成磨蚀坑,而腐蚀消弱了褶皱与基体的连接,使得褶皱易于脱离,加速了材料的磨蚀失重。     

Ni-Cr-Mo合金化HB500级耐磨钢耐腐蚀磨损性能研究

为提高腐蚀磨损条件下耐磨钢使用寿命，通过浸泡试验、磨损试验和腐蚀磨损试验以及微观组织表征方法，研究了Ni-Cr-Mo合金化HB500级耐磨钢的耐腐蚀性能、耐磨损性能、耐腐蚀磨损性能以及表面特征，并探讨了腐蚀与磨损相互作用机理。结果显示，纯腐蚀、纯磨损以及腐蚀与磨损交互作用分别占腐蚀磨损总量的0.2%、82.9%、16.9%，表明在腐蚀条件下磨损性能恶化，磨损过程中材料表层状态发生变化使腐蚀与磨损相互促进，是产生腐蚀与磨损交互作用的主要原因，降低腐蚀与磨损的交互作用，有利于提高耐腐蚀磨损性能。     

Ni-Cr-Mo合金化HB500级耐磨钢耐腐蚀磨损性能研究

为提高腐蚀磨损条件下耐磨钢使用寿命,通过浸泡试验、磨损试验和腐蚀磨损试验以及微观组织表征方法,研究了Ni-Cr-Mo合金化HB500级耐磨钢的耐腐蚀性能、耐磨损性能、耐腐蚀磨损性能以及表面特征,并探讨了腐蚀与磨损相互作用机理。结果显示,纯腐蚀、纯磨损以及腐蚀与磨损交互作用分别占腐蚀磨损总量的0.2%、82.9%、16.9%,表明在腐蚀条件下磨损性能恶化,磨损过程中材料表层状态发生变化使腐蚀与磨损相互促进,是产生腐蚀与磨损交互作用的主要原因,降低腐蚀与磨损的交互作用,有利于提高耐腐蚀磨损性能。     

An approach to modelling erosion-corrosion of alloys using erosion-corrosion maps

A model has been developed to establish the boundaries on erosion-corrosion maps, where increases in erosion and corrosion are represented by increases in velocity and temperature respectively. The maps show the transitions through the regimes as functions of the main erosion-corrosion variables. The effects of additional parameters such as alloy corrosion resistance and particle flux on the transition boundaries on the maps are simulated in the model. This paper outlines the preliminary work which has been carried out on the mathematical algorithms used to calculate the transition boundaries. The variations in the location of the boundaries with target and particles properties are illustrated. Future development of the maps is discussed in terms of extension of the erosion-corrosion algorithms, and applications to in-service erosion-corrosion problems.     

Slurry erosion-corrosion characteristics of squeeze cast aluminum alloy-aluminum borate composite

The slurry erosion-corrosion behavior of 19.5 vol.% Al₁₈B₄O₃₃ whisker reinforced AC4C Al composite in aqueous slurry containing 3.5 wt.% NaCl and 20 wt.% silica has been investigated using a jet-in-slit rig. Erosion-corrosion tests were performed with slurry having a jet velocity range 6.4 ms⁻¹ to 15.2 ms⁻¹ and at normal impact angle. The results indicated that the slurry erosion-corrosion characteristics were affected by the slurry velocity and material properties. At low slurry velocities, as compared to the unreinforced alloy, the erosion-corrosion resistance of the composite was improved because of increase in hardness as a result of whisker addition. However, steady-state erosion-corrosion rate was found to increase with the addition of whisker to the matrix alloy at high slurry velocities. The erosion-corrosion rates of materials in the saline slurry were much higher than those in the water slurry even though the corrosion components were very small. It is found that the synergistic factor for the materials reduced with increasing slurry velocity although the synergism between erosion and corrosion was greater at high slurry velocity. Localized corrosion occuring in the strain-hardened layer caused a decrease in the fracture strain of composite during erosion-corrosion. In the saline slurry, the material removal was enhanced through cracking of flakes and detaching of whisker induced by stress and corrosion.     

Resistance of Mo-bearing stainless steels and Mo-bearing stainless-steel coating to naphthenic acid corrosion and erosion-corrosion

Naphthenic acid corrosion (NAC) and erosion-corrosion (NAEC) behavior of Mo-bearing (0-7.0 wt.%) stainless steels have been investigated in laboratory to evaluate the essential role of Mo on their NAC and NAEC resistance. The NAC and NAEC resistance of a high-velocity-oxygen-fuel (HVOF) thermal sprayed Mo-bearing stainless-steel coating was also investigated in both laboratory and an oil refinery. It was found that increasing the Mo content remarkably enhanced the NAC and NAEC resistance of stainless steels. The Mo-rich areas or phases in the steels played an importance role in resisting the NAEC. The HVOF coating showed excellent NAC and NAEC resistance in laboratory tests. The 700-day field test in an oil refinery revealed that the coating can effectively prevent the carbon-steel substrate from erosion-corrosion during long-term exposure in oil-refining environment. The corresponding NAC and NAEC mechanisms of the stainless steels and the beneficial role of Mo were discussed by taking account of inherent susceptibility of metal elements to corrosion, possible effects of Mo on surface films, and Mo-induced change in microstructure and microhardness.     

AC-HVAF热喷涂非晶和金属陶瓷涂层在压裂液中的冲蚀行为

采用喷射冲蚀与电化学测试相结合方法,对AC-HVAF热喷涂非晶金属和金属陶瓷两种涂层在压裂工况下的冲蚀规律进行了研究,评价了腐蚀和冲蚀的交互作用,分析了耐蚀性和硬度在冲蚀时的主导作用,确定了冲蚀机理。结果表明,硬度决定材料的抗冲蚀性能,硬度高的WC涂层表现出更高的抗冲蚀能力。冲蚀过程中,纯机械冲刷引起的失重占主导作用。交互作用中,涂层由腐蚀引起的增量占比例则较高,提高涂层耐蚀性可以减少交互作用失重,进而提高其抗冲蚀性能。AC-HVAF涂层表面则呈现出脆性冲蚀特征,冲蚀时侧重于固体砂粒对表面的碰撞和切削剥蚀作用。涂层孔隙的降低和粘结相结合强度的提高是提高其在压裂液中抗冲蚀性能的关键。     

Cr3C2-NiCr and WC-Ni thermal spray coatings as alternatives to hard chromium for erosion-corrosion resistance

Cr₃C₂-NiCr and WC-Ni coatings are widely used for wear applications at high and room temperature, respectively. Due to the high corrosion resistance of NiCr binder, Cr₃C₂-NiCr coatings are also used in corrosive environments. The application of WC-Ni coatings in corrosive media is not recommended due to the poor corrosion resistance of the (pure Ni) metallic matrix. It is well known that the addition of Cr to the metallic binder improves the corrosion properties. Erosion-corrosion performance of thermal spray coatings is widely influenced by ceramic phase composition, the size of ceramic particles and also the composition of the metallic binder. In the present work, two types of HVOF thermal spray coatings (Cr₃C₂-NiCr and WC-Ni) obtained with different spray conditions were studied and compared with conventional micro-cracked hard chromium coatings. Both as-sprayed and polished samples were tested under two erosion-corrosion conditions with different erosivity. Tungsten carbide coatings showed better performance under the most erosive condition, while chromium carbide coatings were superior under less erosive conditions. Some of the tungsten carbide coatings and hard chromium showed similar erosion-corrosion behaviour under more and less erosive conditions. The erosion-corrosion and electrochemical results showed that surface polishing improved the erosion-corrosion properties of the thermally sprayed coatings. The corrosion behaviour of the different coatings has been compared using Electrochemical Impedance Spectroscopy (EIS) and polarization curves. Total material loss due to erosion-corrosion was determined by weight loss measurements. An estimation of the corrosion contribution to the total weight loss was also given.     

Effects of Rare Earth Metal addition on the cavitation erosion-corrosion resistance of super duplex stainless steels

Austenitic stainless steels such as AISI 316L have been used in equipment in which fluid flows at high speeds which can induce cavitation erosion on metallic surfaces due to the collapse of cavities, where the collapse is caused by the sudden change of local pressure within the liquid. Usually AISI 316L is susceptible to cavitation erosion. This research focuses on developing a better material to replace the AISI 316L used in equipment with high speed fluid flow, such as impellers. The effects of Rare Earth Metal (REM) additions on the cavitation erosion-corrosion resistance of duplex stainless steels were studied using metallographic examination, the potentiodynamic anodic polarization test, the tensile test, the X-ray diffraction test and the ultrasonic cavitation erosion test. The experimental alloys were found to have superior mechanical properties due to interstitial solid solution strengthening, by adding high nitrogen (0.4%), as well as by the refinement of phases and grains induced by fine REM oxides and oxy-sulfides. Corrosion resistance decreases in a gentle gradient as the REM content increases. However, REM containing alloys show superior corrosion resistance compared with that of other commercial alloys (SAF 2507, AISI 316L). Owing to their excellent mechanical properties and corrosion resistance, the alloys containing REM have high cavitation erosion-corrosion resistance.     

动态与静态纯腐蚀对定量研究材料冲刷腐蚀交互作用的影响

分别测定了不锈钢和碳钢静态与动态纯腐蚀失重率、冲刷腐蚀失重及其电化学行为。研究了静态与动态纯腐蚀失重率对材料冲刷腐蚀交互作用失重率的影响。实验表明：（1）动态纯腐蚀比静态纯腐蚀更能反映材料在液固两相流中冲刷腐蚀交互作用的本质；（2）本实验条件下。T8钢动态纯腐蚀失重率是静态纯腐蚀失重率的2倍以上。18－8不锈钢动态纯腐蚀失重率竟是静态纯腐蚀失重率200倍以上、静态交互作用失重是动态交互作用失重率的2倍以上。可见静态与动态纯腐蚀对定量研究材料冲刷腐蚀交互作用会产生很大的差异；（3）在腐蚀性浆料中，首先要保证材料具有一定的耐蚀性。其次再考虑提高材料的硬度和耐磨性。这样才能有效地提高材料的耐冲刷腐蚀性能。对不同的工况，必须同时兼顾材料的耐蚀性和耐磨性。     

Modelling of erosion-corrosion in practical geometries

The limiting factor in certain instances of erosion-corrosion of steel is the presence of dissolved oxygen in the solution and the transfer of this oxygen to the reacting surface. Computational Fluid Dynamics (CFD) can be used to calculate oxygen diffusion throughout the flow and its transfer to the reacting surface. This was used in a computational model to calculate wear and validated against experimental results, for the first time, of erosion-corrosion wear in a contracting-expanding geometry. It was found that in order to correctly predict erosion-corrosion wear, Sherwood number independent grids were required providing a new metric to evaluate turbulent erosion-corrosion modelling. The predicted wear profile matched very closely with experimental results and overall matching was very good. Downstream of the flow expansion, erosion-corrosion wear was under-predicted. The disparity is due to detached flow for most of this sector where under-predicted radial velocities decrease transfer of oxygen to the reacting surface. This under-prediction is apparent in the downstream section due to the larger relative magnitude of the radial velocity in this sector.