四匝感应圈与倾斜感应圈表面感应淬火丝杠光杆的工艺分析

分别采用四匝感应圈与倾斜30°单匝感应圈对国产CrMo钢与德国CrMo钢丝杠光杆进行表面感应加热淬火处理,经材料成分、显微组织、表面淬硬层的硬度梯分布等检验,综合分析了表面感应加热淬火的工艺质量。结果表明,两种CrMo钢的化学成分存在差别,经四匝感应圈和倾斜30°单匝感应圈感应淬火处理后的组织基本相同;但经四匝感应圈感应淬火处理的淬硬层深度均大于经倾斜30°单匝感应圈感应淬火处理的结果。而且德国CrMo钢的淬硬层深度均大于国产CrMo钢,这与德国CrMo钢的淬透性高于国产CrMo钢有关。     

机械传动丝杠用ZG30CrMnSiMoTi钢淬火工艺研究

研究了机械传动丝杠用ZG30CrMnSiMoTi钢的淬火工艺。结果表明,当感应加热温度稍高于A_(c3)时可得到细小的马氏体组织。随着加热速率增加,ZG30CrMnSiMoTi钢奥氏体化完成所需时间越来越短,该钢种的奥氏体化起始与完成温度与加热速率成正比。传动部件在单感应圈感应加热时厚度方向上存在着温度梯度,这在随后的冷却过程中将会导致淬硬层硬度不均匀分布和应力开裂;双感应圈感应加热后完全奥氏体化厚度大,且沟道端部和底部之间温度接近,在端部淬火时残余应力很小、无裂纹产生。     

精化55钢滚珠丝杠双匝感应加热淬火及性能分析

通过精化国产55钢的成分,提高Mn元素含量,降低P元素含量,在保持55钢力学性能的前提下,提升其热处理性能,Ms(马氏体开始转变温度)和Mf点分别为282℃和220℃。采用双匝感应器对55钢滚珠丝杠进行表面感应淬火,淬火后丝杠沟道顶部及底部都得到了理想深度的淬硬层,且硬度梯度分布合理;淬火后丝杠表层呈现低压应力状态,摩擦系数稳定在0.6,精度保持性试验证明丝杠精度保持性良好。利用数值模拟,得到了双匝感应器加热冷却时丝杠沟道处的温度分布曲线,阐释了双匝感应淬火机理。     

45钢光轴连续感应淬火过程的数值模拟

建立45钢无限长轴对称工件连续感应淬火过程的二维物理模型,并进行温度场的数值模拟。根据连续感应淬火过程中温度场的分布给出了判断淬硬层深度的依据,并结合Maynier组织预测模型与硬度公式计算出工件不同深度处的硬度值进行验证。结果表明,可根据工件感应加热区域进入喷水冷却时刻的径向温度分布曲线来预测连续感应淬火最终淬硬层深度。根据这一结论,可以用所建立的有限元模型对连续感应淬火工件淬硬层深度进行预测。     

三维点式感应淬火电磁热耦合场数值模拟

针对45钢三维点式感应淬火工艺进行参数设计,建立点式感应淬火过程的电磁场及温度场的非线性偏微分方程组,在有限元软件ANSYS中使用耦合场分析的方法实现了对加热功率为36 kW,电流频率为50 kHz的感应热处理工艺的数值模拟.结果表明,在综合考虑表面组织完全奥氏体化及感应加热效率的情况下,该工艺的最佳加热时间约为2 s.通过模拟分别得到使用冷却水和冷却油作为冷却介质时的感应淬火过程中的温度变化规律,结合45钢的连续冷却转变曲线,以马氏体转变临界冷却速度为判断依据,对淬火后工件表面组织进行预测,结果表明两种淬火条件均可以实现表面组织马氏体转变,实现工件的表面强化,且淬硬深度均约为1.0 mm.     

双列球轴承中频感应淬火数值模拟

基于温度场、组织场、电磁场和应力/应变场耦合模型,对双列球轴承的感应淬火过程进行数值模拟,研究感应淬火过程中轴承内圈各部位的升温过程、冷却过程、组织转变和应力变化等。结果表明:感应加热的升温速度会随着感应频率和电流密度的增大而增大;感应加热后一般的淬硬层深度为2.1 mm,淬硬层的深度会随着感应频率的增加逐渐降低;在残留奥氏体较多的部位残余应力较大;感应加热时轴承各个部位的升温速度与感应器形状有关。     

台阶轴连续感应淬火组织硬度分布预测及其工艺优化

建立了S45C钢台阶轴连续感应淬火过程的分区模拟模型,加载相应的物性和工艺参数,采用感应加热结束时刻轴径向温度分布、Maynier模型、Carsi修正模型和钢CCT曲线拟合预测其淬硬层深度分布,通过联动分析各方法的模拟结果优化了连续感应淬火工艺参数。结果表明,感应淬硬层中关键点b的100%、50%和0%马氏体的模拟深度分别为1.31、1.49和2.97 mm,误差分别为-12.67%、-13.87%和-1.00%,关键点e分别为1.44、2.02、2.54 mm,误差分别为-4.00%、-3.38%和-18.06%,与试验结果较吻合。通过感应淬火工艺参数改变和物理模型调整等探讨了零件各点处的轴径淬硬层变化,给出拟优化的感应淬火工艺参数。初步探讨了换热系数h变化对感应淬硬层的影响。     

国产55钢与日本S55C钢丝杠光杆的表面感应加热淬火工艺质量分析

分别采用双匝感应器和倾斜30°单匝感应器的表面感应加热淬火工艺处理了国产55钢与日本S55C钢丝杠光杆,并对处理后的丝杠光杆进行了显微组织分析和硬度测试。结果表明,日本S55C钢组织中的带状偏析较国产55钢明显;经双匝感应器处理的国产55钢与日本S55C钢的淬硬层深度基本一致;而经倾斜30°单匝感应器处理的国产55钢的淬硬层较深、硬度较高。因此,可以采用国产55钢替代日本S55C钢制作f40 mm以下小规格的滚珠丝杠。     

TY320单双边支重轮感应淬火工艺研究

在立式中频感应淬火设备中对TY320单双边支重轮进行淬火处理改进工艺研究。结果表明,采用多次同时均匀加热然后冷却的方式,大大提高了TY320支重轮的硬度和淬硬层深度,提高生产率50%,降低了废品率和劳动强度。     

曲轴感应淬火及残余应力的仿真与试验研究

曲轴在感应淬火时产生应力集中或应力分布不均会导致曲轴变形过大而失效。本文采用有限元方法对曲轴加热和冷却过程及残余应力进行了仿真,并对轴颈显微组织、轴颈淬硬层深度及曲轴残余应力进行了测试分析。结果表明,轴颈淬硬层为细针状马氏体,基体为回火索氏体,表面平均硬度为52.8 HRC,心部硬度为26.0~30.0 HRC,淬火后轴颈表面残余压应力为-154.3~-254.9 MPa;连杆颈淬硬层深度为4.0 mm,过渡圆角处淬硬层深度为2.1 mm。曲轴感应淬火后淬硬层深度预测和残余应力的仿真结果与试验结果基本一致,仿真可预测淬硬层深度。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.