“华龙一号”核电厂堆内构件钴基合金堆焊优化设计

核反应堆堆内构件的左、右嵌入件与导向销以及径向支承键与U形嵌入件需进行钴基合金堆焊以保证耐磨性能。前期核电项目采用手工钨极氩弧堆焊,堆焊层会出现不同程度的气孔、夹杂甚至裂纹,导致较多不符合项的产生。在大量吸取前期核电厂堆焊经验教训的基础上,本文对堆内构件钴基合金堆焊从设计和工艺方面进行了优化改进,改进后的检验结果显示,堆焊层质量大大提高,表层硬度均匀,硬度线过渡柔和,堆焊层缺陷大大减少。     

核级阀门密封面堆焊

叙述了核级阀门密封面堆焊用钴基合金的牌号分类、化学成分、硬度、金相组织及主要性能,较为详细地介绍了几种堆焊钴基合金方法的工艺特点及堆焊核级阀门密封面的技术要求,明确了核级阀门密封面堆焊的焊接工艺评定准则和质量控制要求。     

钴基合金滚珠轴承的研制

本文叙述了钴基合金滚珠轴承的主要制造工艺及经验。在轴承内外圈的堆焊中,不是采用文献中所报道的与滚珠同硬度的堆焊材料,而是采用硬度较低的St-6合金,最终经热处理使其硬度达到与滚珠相当的水平。这种改进具有一定的优越性。整个制造工艺的经验表明。严格控制内外圈堆焊工艺是保证轴承质量的关键问题。     

核阀密封面无钴镍基熔覆层高温性能研究

设计一种无钴镍基合金材料Ni-3,其在高温下耐磨损和耐腐蚀性能接近或超过钴基合金。在350℃左右的温度下分别对Ni-3、Norem02和Stellite06进行高温摩擦磨损及高温腐蚀的实验。分析结果表明,Ni-3是一种较为理想的无钴合金材料,在高温耐磨损和耐腐蚀性能方面都比代钴材料Norem02优越;与钴基合金相比,Ni-3高温耐磨损性能与之接近,高温耐腐蚀性能稍逊色。在一定范围内,Ni-3可以替代目前在核阀、化工等阀门密封面上普遍使用的堆焊合金。     

核电站用阀门零件激光熔覆层的组织研究

应用5kW横流CO2激光器对核阀阀瓣密封面进行钴基合金的激光熔覆处理，用金相显微镜，扫描电镜，能谱分析仪等分析手段对涂层的组织，晶粒度，显微硬度和稀释率进行了分析，结果表明，熔覆层的显微组织，晶粒度，熔层稀释率，热影响区宽度，显微硬度等均显著优于等离子喷焊和堆焊工艺。     

反应堆压力容器法兰密封面材料的性能研究

采用手工惰性气体钨极保护焊(TIG焊)制备反应堆压力容器密封面材料E308LMoT0-3、E309LMoT0-3及对比材料ER308 L的不锈钢堆焊层,对其进行硬度测试、显微组织观察、抗晶间腐蚀性能分析,以及点蚀点位测量和偏离水质条件下的局部腐蚀试验,研究E308LMoT0-3、E309LMoT0-3堆焊材料的点腐蚀和缝隙腐蚀性能以及腐蚀机理。试验结果表明,E308LMoT0-3、E309LMoT0-3焊丝堆焊后的试样除了具有良好的硬度、耐晶间腐蚀性能外,还具有良好的耐局部腐蚀性能,可以代替目前压水堆核电厂普遍使用的ER308L不锈钢堆焊材料。     

核阀零件激光熔覆工艺合理性研究

采用激光熔覆、等离子喷焊和电弧堆焊３种工艺分别对核阀阀瓣密封面进行了Ｃｏ基合金的强化处理，对所形成的熔层的组织和性能进行了试验分析，对３种工艺的综合成本进行了对比。结果表明：激光熔覆工艺具有生产率高、能耗低，熔覆层加工余量小，成品率高以及综合成本低等特点；激光熔覆核阀零件的质量和使用寿命明显高于等离子喷焊和电弧堆焊处理的核阀零件。因此，激光熔覆工艺是一项很有发展前途的新技术。     

对AP1000堆芯补水箱裂纹产生原因的分析

三门核电站2号机组两台AP1000堆芯补水箱在制造过程中先后发生简体堆焊层二次下裂纹问题，通过对现场二次UT缺陷分布类比、母材及堆焊层缺陷处材料化学成分分析对比、硬度试验、金相照片和复膜金相照片观察，对堆焊工艺、技术方面的问题进行了分析与研究，初步确定了裂纹产生的根本原因，并提出一些工艺质量控制措施，旨在为避免今后发生类似问题，为提高主设备制造质量提供一些参考与借鉴。     

核阀零件密封面的激光熔覆强化

介绍在核阀阀瓣奥氏体基体上采用5kW横流激光器熔覆Co基或Ni基合金形成密封面,与传统的等离子喷焊和火焰、电弧堆焊相比,激光熔覆核阀密封面可获得厚度达3.5mm、表面平整光滑的合金层。检测的结果表明,其组织性能和成品率等方面均明显优于传统的喷焊、堆焊工艺。     

激光熔覆核阀零件的研究(英文)

应用激光熔覆的传热模型、热传导模型和激光熔焊的对流传质模型,对激光熔覆机理进了分析讨论,随后分析了激光熔覆速度极限和熔覆工艺参数对熔层组织结构的影响。使用5kW横流CO_2激光器对核电站使用的截止阀零件密封面进行了激光熔覆处理,经检测:激光熔层可达3.0mm厚,其表面光滑平整,无裂纹、气孔等缺陷。与传统的等离子喷焊、电弧堆焊工艺进行测试比较,其结果说明:激光熔层中的组织晶粒度和硬度更高,稀释率更低,抗摩擦磨损和抗腐蚀性性能更好。激光熔覆新技术能明显改善核阀的质量,可以延长核阀的服役期、提高生产系统的安全性和可靠性。     

Influence of irradiation number of high current pulsed electron beam on the structure and properties of M50 steel

The influence of high current pulsed electron beam (HCPEB) irradiation numbers on the microstructure, wear and corrosion resistance properties of M50 steel was studied. The crystallize phase, surface morphology, hardness, oxidation wear and corrosion resistance of samples were analyzed using XRD, SEM, nanoindenter, wear tester and electrochemical corrosion tests. The results reveal that the hardness and wear resistance of irradiated samples decrease compared with untreated sample because of the increasing of austenite content in the melted layer; while the corrosion resistance of irradiated samples is higher than untreated sample.     

Comparison study on resistance to wear and abrasion of high-temperature sliding strike of laser and plasma spray layer on the stainless steel surface

In this paper, the effect of coatings, which are formed with laser cladding and plasma spray welding on 1Cr18Ni9Ti base metal of nuclear valve seats, on wear resistance is studied. A 5-kW transverse-flowing CO₂ laser is used for cladding Co base alloy powder pre-placed on the substrate. Comparing with the plasma spray coatings, the laser-cladding layer have lower rate of spoiled products and higher rate of finished products. Their microstructure is extremely fine. They have close texture and small-size grain. Their dilution diluted by the compositions of their base metal and hot-effect on base metal are less. The hardness, toughness, and strength of the laser-cladding layers are higher. The grain size is 11–12th grade in the laser-cladding layer and 9–10th in the plasma spray layer. The width of combination zone between laser-cladding layer and substrate is 10–45 μm but that between plasma spray layer and substrate is 120–160 μm. The wear test shows that the laser layers have higher property of anti-friction, anti-scour, and high-temperature sliding strike. The wear resistance of laser-cladding layer is about one time higher than that of plasma spray welding layer.     

Laser cladding of Colmonoy 6 powder on AISI316L austenitic stainless steel

Stainless steels are widely used in nuclear power plant due to their good corrosion resistance, but their wear resistance is relatively low. Therefore, it is very important to improve this property by surface treatment. This paper investigates cladding Colmonoy 6 powder on AISI316L austenitic stainless steel by CO₂ laser. It is found that preheating is necessary for preventing cracking in the laser cladding procedure and 450 °C is the proper preheating temperature. The effects of laser power, traveling speed, defocusing distance, powder feed rate on the bead height, bead width, penetration depth and dilution are investigated. The friction and wear test results show that the friction coefficient of specimens with laser cladding is lower than that of specimens without laser cladding, and the wear resistance of specimens has been increased 53 times after laser cladding, which reveals that laser cladding layer plays roles on wear resistance. The microstructures of laser cladding layer are composed of Ni-rich austenitic, boride and carbide.     

High temperature wear and corrosion resistance of Co-free Ni-based alloy coatings on nuclear valve sealing surfaces

As a further step in obtaining high temperature wear and corrosion performances of a newly designed and laser cladded cobalt-free, nickel-based alloy coating (Ni-3) used for sealing surfaces of nuclear power valves, high temperature dry sliding wear behavior was characterized on a HT-1000 ball-on-disk tribometer at 360 °C, the hot corrosion test was conducted by plating Na₂SO₄ + K₂SO₄ mixed salt solution on the coating at 350 °C for 140 h. For comparison, the high temperature wear and corrosion resistance of the laser cladded Co-based Stellite06 and Fe-based Norem02 coatings were also investigated at the same testing conditions. It is found that the microhardness of the Ni-3 coating is about HV500 and close to Stellite06, but less than Norem02, the high temperature wear volume loss of Ni-3 coating is half of Norem02 and close to Stellite06. While during 350 °C hot corrosion test, the mass loss of Norem02 coating is the largest, Ni-3 coating is placed in the middle, Stellite06 coating shows the best hot corrosion resistance. Thus, the newly designed and laser cladded Ni-3 alloy coating appears to be the viable alternative material and technique for Co-free alloy, especially used in the nuclear valve sealing surfaces.     

Potential of direct metal deposition technology for manufacturing thick functionally graded coatings and parts for reactors components

Direct metal deposition (DMD) is an automated 3D deposition process arising from laser cladding technology with co-axial powder injection to refine or refurbish parts. Recently DMD has been extended to manufacture large-size near-net-shape components. When applied for manufacturing new parts (or their refinement), DMD can provide tailored thermal properties, high corrosion resistance, tailored tribology, multifunctional performance and cost savings due to smart material combinations. In repair (refurbishment) operations, DMD can be applied for parts with a wide variety of geometries and sizes. In contrast to the current tool repair techniques such as tungsten inert gas (TIG), metal inert gas (MIG) and plasma welding, laser cladding technology by DMD offers a well-controlled heat-treated zone due to the high energy density of the laser beam. In addition, this technology may be used for preventative maintenance and design changes/up-grading. One of the advantages of DMD is the possibility to build functionally graded coatings (from 1 mm thickness and higher) and 3D multi-material objects (for example, 100 mm-sized monolithic rectangular) in a single-step manufacturing cycle by using up to 4-channel powder feeder. Approved materials are: Fe (including stainless steel), Ni and Co alloys, (Cu,Ni 10%), WC compounds, TiC compounds. The developed coatings/parts are characterized by low porosity (<1%), fine microstructure, and their microhardness is close to the benchmark value of wrought alloys after thermal treatment (Co-based alloy Stellite, Inox 316L, stainless steel 17-4PH). The intended applications concern cooling elements with complex geometry, friction joints under high temperature and load, light-weight mechanical support structures, hermetic joints, tubes with complex geometry, and tailored inside and outside surface properties, etc.     

Wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The wear and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100–300 A/cm² with shot number of 1–10 are investigated by sliding wear test and potentiodynamic polarization measurement. The surface and cross-sectional morphologies, phase structure and surface microhardness of the irradiated AZ31 magnesium alloy samples are characterized by scanning electron microscopy (SEM), optical microscopy, X-ray diffraction (XRD) and Vickers tester, respectively. The HIPIB irradiation produces the hardened surface layers and improves abrasive wear resistance of all the samples. The wear volume of the irradiated samples at 200 A/cm² and 300 A/cm² with 10 shots as well as 100 A/cm² with 5 shots is about four times less than that of the original sample. The apparent increase in corrosion resistance is achieved for all the irradiated samples in 0.01 mol/l NaCl solution with a pH value of 12. The corrosion potential and pitting breakdown potential for the samples irradiated at 100 A/cm² with 5 shots are 560 and 630 mV higher than those of the original sample, −1560 mV and −1300 mV (SCE), respectively. It is found that the combined improvement in wear and corrosion resistance of AZ31 magnesium alloy is achieved by HIPIB irradiation, which is ascribed to the microstructural refinement and the chemical homogeneity of the irradiated magnesium alloy.     

核阀阀瓣激光熔覆层显微组织和耐高温磨损性能研究

应用 5kW横流CO2 激光器对核阀阀瓣密封面进行Co基合金的激光熔覆处理 ,对激光熔覆层和等离子熔涂涂层进行了显微组织分析和抗高温冲击滑动磨损性能对比试验研究。结果表明 :激光熔覆层的组织细密均匀 ,气孔、夹杂物少 ,稀释率低 ,其抗高温冲击滑动磨损性能明显高于等离子熔涂工艺。     

Low activation steels welding with PWHT and coating for ITER test blanket modules and DEMO

EUROFER weldability is investigated in support of the European material properties database and TBM manufacturing. Electron Beam, Hybrid, laser and narrow gap TIG processes have been carried out on the EUROFER-97 steel (thickness up to 40 mm), a reduced activation ferritic-martensitic steel developed in Europe. These welding processes produce similar welding results with high joint coefficients and are well adapted for minimizing residual distortions. The fusion zones are typically composed of martensite laths, with small grain sizes. In the heat-affected zones, martensite grains contain carbide precipitates. High hardness values are measured in all these zones that if not tempered would degrade toughness and creep resistance. PWHT developments have driven to a one-step PWHT (750 °C/3 h), successfully applied to joints restoring good material performances. It will produce less distortion levels than a full austenitization PWHT process, not really applicable to a complex welded structure such as the TBM. Different tungsten coatings have been successfully processed on EUROFER material. It has shown no really effect on the EUROFER base material microstructure.     

高温堆非纯氦气中预氧化对3种高温合金的腐蚀行为影响研究

高温气冷堆（简称高温堆）中,由于一回路冷却剂氦气中含有微量（ppm级）不纯杂质,其在高温环境中会对高温堆合金材料造成腐蚀,影响设备的性能。Inconel 617、Hastelloy X、Incoloy 800H是3种高温堆中间换热器及蒸汽发生器设备候选材料。研究表明,镍铬合金在高温下表面生成的富铬氧化层是防止合金在高温下发生严重腐蚀的重要因素。本文对3种合金在高温含杂质氦气中的腐蚀行为进行研究,探究预氧化对3种合金腐蚀行为的影响。并通过称重、扫描电镜、X射线能谱、电子探针显微分析仪以及碳硫分析仪对腐蚀结果进行分析。结果表明,3种合金均出现了不同的氧化和渗碳现象,预氧化对Hastelloy X合金抗腐蚀能力的提升不明显,对Inconel 617合金的抗氧化和渗碳能力有一定提升,对Incoloy 800H合金的抗渗碳腐蚀能力有一定提升。