激光陶瓷合金化

通过陶瓷合金化涂料的研制,在激光淬火的工艺条件下获得激光陶瓷合金化层.经过陶瓷合金化的钢铁材料,其耐磨性能比激光淬火高约一倍.陶瓷合金化涂料具有与目前广泛使用的激光淬火吸光涂料同样的粘结性能,吸光性能和施涂工艺性能.激光陶瓷合金化是纳米技术、氮化硅应用技术、稀土应用技术、不同质材料之间的偶联技术,激光加工技术和涂料粘结...     

纳米陶瓷球作细磨介质下的磨矿动力学

以0～0.3 mm铁粗精矿作磨矿样品,对其磨矿产品进行了磨矿动力学和箱线图求解,对比分析了陶瓷球和钢锻研磨不同粒级给矿产品下磨矿速度与产品粒度分布特征区别.磨矿动力学结果表明,陶瓷球的磨细能力比钢锻强,且随着时间的延长,磨细能力越发显著增强.箱线图结果表明,随着磨矿时间的延长,陶瓷球磨矿产品中0.010～0.074 m...     

Semi‐Solid Rheoforging of Steel

To produce steel components with complex shapes excessive machining is necessary frequently since high pressure die casting of steel is not industrially applied. Forming steel in the semi‐solid state can in principle produce new components and geometries which cannot be realised by conventional closed die forging. Semi‐solid forging of steel combines the possibility of producing geometries not conventionally forgeable in one forming operation and of adding further functions during the same operation. In previous investigations on thixoforming of steels, the semi‐solid steel was generated by reheating precursor material billets. An alternative approach for generating semi‐solid steel from the liquid state with subsequent forging operation is presented in this paper for the first time. The steel grades X210CrW12 cold work tool steel and 100Cr6 bearing steel are molten and driven into a globular semi‐solid state using a cooling slope and a cup. By cooling the steel into the semi‐solid range instead of heating it, the required process temperatures are lower than in the process route via heating. Therefore, the load on the dies in a semi‐solid forging operation is decreased. Suggestions for the respective layout of the process are made for both steel grades. Future potentials and challenges to be solved are discussed, showing advantages especially in the field of high melting point alloys such as steels. This technique enables to produce pre‐shaped semi‐solid billets to optimise the materials flow and the homogeneity of the mechanical properties.     

Alloying Design for High Wear-Resistant Cast Hot-Forging Die Steels

The alloying design of cast hot-forging die steels was analyzed. The relationship of the life of cast hot-forging dies with the failure patterns was studied. The thermal wear resistance was believed to be the key property for the alloying design of cast hot-forging die steels. The alloying design parameters were selected and optimized for the cast hot-forging die steel with high wear resistance. The wear resistance of the optimized cast die steel was evaluated in comparison with commercial H13 steels and 3Cr2WSV steel. In the new cast hot-forging die steel, VC is predominant carbide with Cr and Mo as the main solution elements in α-Fe. It is found that the cast die steel has significantly lower wear rate than normal H13 steel and 3Cr2W8V steel, almost the same as that of high purity H13 steel. The high wear resistance of the new cast hot-forging die steel can be attributed to its reasonable alloying design and nonsensibility to the detrimental function of S and P.     

Borided Hot-Worked Powder Materials Based on Iron. Part 3. Wear Resistance and Mechanical Properties

The wear resistance of borided powder materials is studied. The maximum wear resistance with dry friction is obtained with carbon-free iron powder borided before hot forging. For abrasive wear operating conditions it is preferable to use borided carbon steel after heat treatment. It is established that coating billets with nickel before boriding provides an increase in wear resistance. Nickel promotes the formation of borides FeB and NiB with high microhardness. The mechanical properties of borided materials are studied.     

宏观颗粒增强铁基复合材料的制备与性能

颗粒与基体之间难以均匀稳定的混合以及二者的界面结合强度较差是限制颗粒增强金属基复合材料制备以及推广应用的共性关键问题,而目前的主要解决措施"预制体法"以及"润湿化预处理技术"又存在生产效率较低、制备成本较高等问题.基于此,在液态模锻的基础上,提出了不做预制体、也不进行润湿化预处理的制备颗粒增强金属基复合材料的新技术——"随流混合＋高压复合"技术,并采用此方法成功制备了复合效果良好的ZTA/KmTBCr26抗磨复合材料.研究了ZTA/KmTBCr26复合材料的微观组织、硬度以及冲击性能,发现复合材料内部颗粒分布比较均匀,颗粒与KmTBCr26基体的结合紧密,属于微机械啮合.冲击试验结果表明,复合材料的冲击韧性与单一金属基体相比显著降低,冲击断口形貌显示材料的断裂是沿颗粒内部扩展的,没有出现颗粒的整体脱落,说明陶瓷颗粒与金属基体具有比较高的结合强度.考察了ZTA/KmTBCr26复合材料与单一KmTBCr26的干摩擦磨损性能,结果表明,低载荷条件下ZTA/KmTBCr26复合材料的磨损性能是KmTBCr26的1.82倍,而高载荷条件下复合材料的磨损性能则是KmTBCr26的3.3倍.      

应用钎焊轧制法生产不锈钢复合板

针对目前不锈钢复合板各生产方法存在的诸多不足,研制开发了钎焊轧制法.该方法采用钎焊机理,在高温下实现钎焊轧制.试验和应用表明,钎焊轧制法生产的复合板达到了国标要求,在剪切强度和批量生产方面分别优于直接轧制法和爆炸复合法.     

Hot Forging of C45 using PVD (Ti,Al)N/γ‐Al2O3 Coated Dies

The process of hot forging with permanent moulds is a challenge in respect to the very high thermal, mechanical and tribological loads on tools. Ensuring sufficient lifetime application of protective films can be beneficial. Initial screening experiments using PVD coated compression plates show that one of the metastable phases of alumina, the γ‐phase, exhibits high strength and toughness and fulfils the requirements for a protective coating. The next important step in the development towards an industrial application is the implementation on complex tool shapes and verification in real forming experiments. After coating deposition using an industrial coating unit, coated dies were tested in forming experiments under industrial conditions. The forming experiments show an improvement of the wear resistance after 1000 forming cycles for the coated dies compared to the uncoated dies.     

电弧喷涂含陶瓷颗粒铝基复合涂层的微结构和性能

采用5052半硬铝带分别包覆Al_2O_3、SiC、B_4C、TiC陶瓷颗粒制备的粉芯丝材进行电弧喷涂试验,制备了含陶瓷颗粒的铝基复合涂层。利用光学显微镜、XRD分析了涂层的微观组织和相结构,测试了复合涂层的显微硬度、耐磨性及耐腐蚀性。研究结果表明,制备的铝基复合涂层中含有一定数量的未熔陶瓷颗粒,涂层较为致密,无明显缺陷。含陶瓷铝基涂层的物相主要由Al和所添加的陶瓷相构成,其中在含B_4C陶瓷涂层中还存在Al_3BC、Al_4C_3和AlB_2等新相。陶瓷颗粒的加入有利于提高铝基复合涂层的显微硬度,其中B_4C的加入使涂层中基体相显微硬度提高了1.5倍,这是由于B_4C陶瓷和Al反应生成Al_3BC、Al_4C_3和AlB_2硬质相。复合涂层的耐磨性均优于纯铝涂层,摩擦磨损的形式主要为粘着磨损。动电位极化腐蚀试验表明,含SiC和TiC陶瓷涂层具有较低的腐蚀电流,耐蚀性较好,含SiC陶瓷的复合涂层出现了明显的钝化现象。     

提高5CrNiMo锻模钢性能的研究

本文采用空冷淬透性试验,力学性能和相分析等方法研究了合金元素对5CrNiMc钢工艺性能和力学性能的影响,找到了钢中合金元素含量偏低是造成国产锻模钢淬透性较低,回火稳定性较差的关键原因。将5CrNiMo钢的锰、钼、铬含量适当提高和加入0.1％钒,可使模块的淬透性,回火稳定性达到国际同低型优质模块的水平,而且提高了钢材的高温强度。另外,在热锻模具使用硬度的范围内,调整成分的钢材具有更高的冲击韧性,从而提高了模具的使用寿命。该研究结果已被工业生产实践证实,具有明显的经济效益。     

Thixocasting Steel Hand Tools using Al2O3‐coated Steel and Molybdenum Dies

Forging is state‐of‐the‐art for producing hand tools on an industrial scale. Due to high demands on the stiffness and the fracture toughness, high‐strength forging steels are used to provide cavity‐free components with high mechanical load capacity. Moreover, forging is a cost‐effective mass production process but, in spite of all its advantages, it has its limitations, e.g. in the freedom of designs. However, because of the extreme thermal loading (particularly with regard to permanent moulds) and the frequently unavoidable casting defects, hand tools are not cast. By means of thixocasting steel, technical difficulties can be reduced and new options are provided which allow the manufacturing of components with much higher complexity than that using forging. Through near‐net shape production, manufacturing steps and costs can be reduced. Furthermore, steels, which are difficult to forge but nonetheless have high potential for specific applications (such as high strength or corrosion resistant steels), can also be processed. In cooperation with industrial partners, X39CrMo17 stainless steel size 17 combination spanners were thixocast. Forming dies were designed and optimized by simulation, the hot forming X38CrMoV5 tool steel as well as the molybdenum alloy TZM were selected as the tool alloys. The dies were treated by a plasma nitriding process and subsequently coated with crystalline Al₂O₃ protective coatings by plasma‐enhanced chemical vapor deposition (PECVD). During the experiments, combination spanners were successfully cast in the semi‐solid state. Cast parts were heat‐treated to enhance the components' toughness, which was subsequently measured by Charpy impact and tensile tests.     

球磨机陶瓷球与钢球混合替代研究及应用

磨矿作业在选矿中占有极其重要的地位,磨矿作业能耗占选矿厂能耗的50%左右。钢球是球磨机中最常用的研磨介质,也是消耗量最大的损耗件。氧化铝耐磨陶瓷球作为一种新型磨矿介质,具有重量轻、强度高、硬度高、耐磨性好、耐温性好等优点。本论文针对贵溪冶炼厂介质成本高、磨矿产品过粉碎含量多等问题开展陶瓷球与钢球的混合替代试验室磨矿试验和工业试验,结果显示介质混合添加能够有效降低磨矿作业电单耗,大幅减少磨矿介质消耗,有效降低磨矿成本,促进指标提升。     

Laser Beam Joining of Dissimilar Thin Sheet Materials

Joining of dissimilar materials is in the focus of many research activities, due to the ability of creating assemblies with advanced functionalities. The functionality can arise either from the physical properties of the interface such as electrical or heat conductivity, or the advantages of weight reduction in light weight constructions. By thermal joining like welding and brazing many metal combinations tend to form intermetallic phases. These phases have a negative influence on the properties of the joint by forming hard and brittle layers. This paper presents a study on laser beam joining of stainless steel to titanium alloy on thin materials for micro‐applications. Two joining technologies are investigated and an optimized process technology for brazing is presented. The results are evaluated with regard to the intermetallic phase formation and the mechanical strength.     

Machining Characteristics of Ce-ZrO2/CePO4 Ceramics

Two-phase mixtures of Ce-ZrO2 and monazite-type CePO4 were fabricated. Drilling and grinding experiments were carried out to investigate the machining characteristics of Ce-ZrO2/CePO4 ceramics. The machined surfaces of ceramics and wear surfaces of drill bits were observed with scanning electron microscope. Material removals and grinding forces were measured. The transgranular fracture of CePO4 grains, intergranular fracture between ZrO2 and CePO4 grains, and ductile deformation of ceramics were observed on Ce-ZrO2/CePO4 machined surfaces. With the increase of CePO4 proportion to composites, drilling material removal rates increases and specific normal grinding forces decreases.There existed rapid wear of conventional metal cutting tool is caused by abrasive wear. The experimental results indicate that the weak interfaces and properties of Ce-ZrO2/CePO4 ceramics have influences on material removal and machinability.     

Reindustrialization principles in the heat treatment of die steels

The reindustrialization of production is considered. As an example, a working model is developed for the heat-treatment equipment used in the production of dies made from special steels. In reindustrialization, productive capacity that has been lost or has grown outdated during deindustrialization must be restored or modernized. Heat treatment is of particular importance since it is part of the manufacture and restoration of most tools. Modern Russian equipment permits high-quality heat treatment of many special steels so as to ensure the required mechanical properties. All the basic groups of die steels are considered in terms of their performance: steel of increased wear resistance; secondary-hardening crumple-resistant steel; steel with elevated impact strength; steel of moderate thermostability and high ductility; steel of elevated thermostability and ductility; and steel of high thermostability. The requirements on the properties of these groups are analyzed, and possible means of attaining those properties by heat treatment are identified. By comparing the specific purpose of die steels, their required properties, and the possible means of attaining those properties by heat treatment, the appropriate equipment is chosen. Modern Russian equipment permits high-quality heat treatment of die steels so as to ensure the required mechanical properties. At present, it is important to create production systems that incorporate the vast wealth of Russian specialists’ accumulated experience and the best available technologies. This is a very complex problem, in both engineering and economic terms.     

TA2钛／Q345R钢钎焊用钎料研究

选用AgSO．5Cu35．2Mn8．01Ni4．95Si0．380．1、Ag60．5Cu26．2Mn8．01Ni4．95Si0．380．1、AS65．5Cu21．2Mn8．0-Ni5Si0．380．1和AgT0．5Cu16．2Mn8．0Ni4．95Si0．380．1为钎焊料,对TA2钛与Q345R钢进行TIG-熔焊连接实验,结合光学显微观察、焊缝显微硬度分析及接头拉伸强度测试,研究了4种钎料对TA2钛与Q345R钢的钎焊效果的影响。结果表明,Ag65．5Cu21．2Mn8．0Ni5SiO．3130．1钎料的焊接质量最好,无论是钢侧还是钛侧都无裂纹产生,也无碳化物以及其他脆性化合物生成,且钎料与母材有明显互扩散现象。     

镍基合金—碳化铬复合涂层抗磨损性能的研究

为了得到耐磨损的表面涂层,用真空熔烧方法制成与钢基休牢固结合的镍基自熔合金—碳化铬复合涂层。用扫描电子显微镜及X射线衍射仪对涂层的组织和结构进行了观察和分析。应用环块磨损试验机,对具有不同碳化铬含量的镍基复合涂层对金属的摩擦副进行了磨损试验。试验结果指出,在同样条件下,在涂层对金属副中的复合涂层的磨损抗力比在金属对金属副中的GCr15钢要好。复合涂层的磨损率比GCr15钢及纯镍基合金涂层降低约一个数量级,并且复合涂层的磨损率是随碳化铬含量增加而下降的。根据试验结果,对在复合涂层中合理的碳化铬含量也进行了讨论。     

Microstructure and high-temperature properties of Fe-Ti-Cr-Mo-B-C-Y_2O_3 laser cladding coating

Fe-based composite coatings were fabricated on 5 CrNiMo die steel by laser beam melting a precursor mixture of ferrotitanium,ferrochromium,ferromolybdenum,B4 C and Y_2 O_3 powders.Micro structure and properties of the coatings were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectrometer(EDS),resistance furnace and high-temperature tribometer.The results show that(Ti,Mo)C particles with flower-like and(Ti,Mo)B_2 with block-like shapes are in situ formed during laser cladding.Volume faction of multiple ceramic particles increases with the increasing of Y_2 O_3.The cumulative oxidation mass of the coating with 2 wt% Y_2 O_3 is decreased by one-third than that of the coating without Y_2 O_3.The oxidation layer of the coating with Y_2 O_3 is getting smooth.Meanwhile,high temperature wear volume loss of the coating with 2 wt% Y_2 O_3 is about 40% that of the coating without Y_2 O_3.The coating with 2 wt% Y_2 O_3 shows a smoother wear scar and few flat grooves are observed after high temperature wear test.     

Model Tests and Analysis of Corrosion Resistance of Ceramic Tool Dies for Steel Thixoforming

Contact corrosion and cyclic melt corrosion test results of silicon nitride (Si₃N₄) ceramics in contact with semi‐solid and molten steel alloys are analysed in view of steel thixoforming applications. Corrosion effects are identified and model tests are evaluated by comparison of corrosive attack on steel thixoforming dies in application‐relevant forming experiments. The performed corrosion experiments show that a reaction zone of up to 20 μm thickness forms on the ceramic in model tests and forming experiments, respectively. Si₃N₄ ceramics reveal sufficient corrosion resistance in small‐scale forming series. Results show good agreement of contact corrosion tests with thixoforming experiments. Comparability of cyclic melt corrosion tests with thixoforming applications is limited by the casting powder used to prevent oxidation of steel melt.     

钢锻作细磨介质下的磨矿能耗与粒度分布特征

钢锻是一种线接触为主的磨矿介质.以1.18~2 mm、0.6~1.18 mm、0.3~0.6 mm 3个粒级样以及实际生产二段沉砂样为研究对象,分别采用等质量的钢球和钢锻进行分批次磨矿试验,分析了其磨矿产品的粒度分布和磨矿能耗分布.结果表明,钢锻作为细磨介质,与钢球相比,磨矿产品有着相同的粒度分布规律,符合JK粒度破碎模型.但在相同磨矿条件下,钢锻磨矿时生产能力比不上钢球.但随着给料粒度的变细,钢锻的磨矿效果开始显现,其磨矿产品中P80值与钢球的差异相差为0.22 %,而t10值与钢球的差异相差为2.23 %.与此同时,磨矿产品中 < 0.010 mm的含量明显低于钢球,过粉碎轻.当采用 < 0.425 mm实际钨矿石作为入磨样品验证时,有着上述相同的结论,从理论上说明了钢锻虽然磨矿能力逊色于钢球,但钢锻产生的合格粒级含量高于钢球,过粉碎情况轻于钢球,对于脆性矿物的细磨是一种优良的磨矿介质选择.