低温高韧性球墨铸铁件转子压板的铸造工艺

通过对转子压板铸件的技术要求及生产难度的分析,分别从造型工艺,浇注系统设计,原材料的控制,化学成分的选择,铁液的熔炼,预处理、球化及孕育处理,热处理工艺等方面阐述了在生产低温高韧性球墨铸铁过程中的工艺控制要点,成功生产了转子压板铸件.经检验,铸件的化学成分、力学性能,金相组织完全符合轨道交通行业用低温球墨铸铁的要求.     

耐-40℃低温冲击材料的研发

试验了不同Ni质量分数、不同温度热处理工艺的球墨铸铁件的低温冲击性能,得到Ni质量分数为0.5%~0.6%、700℃热处理工艺能够达到超规范要求的耐-40℃低温冲击材料要求;同时经过调整炉料配比试验了无Ni球墨铸铁的低温性能,获得铸态无镍达到顾客要求且合格率达到80%以上的球墨铸铁材料,为后续的无镍CRH3定子架铸件生产打下了基础。     

铸态高韧性球墨铸铁QT450-10的生产

我公司球墨铸铁件的生产,以前采用后续热处理的工艺来满足强度、伸长率等要求,造成球墨铸铁件成本高、周期长、废品率高.通过实验我们成功生产了铸态球墨铸铁,本文介绍我公司QT450-10高韧性球墨铸铁托架、制动蹄、制动底板等铸件的生产控制工艺.     

磁悬浮高速铁路球墨铸铁连接件的研制和生产

详细介绍了有特殊力学性能要求的磁悬浮高速铁路复合梁球墨铸铁连接件的研制和生产过程。为了达到高强度、高塑性、并符合低温冲击韧性要求的综合力学性能,进行大量试验比较了各种合金化方案,根据大量实验和研究数据分据,查明了大量生产条件下,该合金球墨铸铁件可能达到的抗拉强度、伸长率和低温冲击值范围,为最终确定该铸件力学性能要求提供了科学依据;进而确定化学成分和铸造工艺,成功试制并大量生产出该铸件。     

真空密封造型在球墨铸铁件上的应用

真空密封造型工艺生产铸钢及普通(孕育)铸铁较为普遍,生产球墨铸铁件相对较少,因为该工艺生产球墨铸铁件时存在抬型和缩松问题.文章中分别论述了负压、充型时间、浇注温度及保压时间等工艺参数对真空密封造型生产球墨铸铁铸件质量的影响,并指出了生产控制要点.     

风电电机端盖低温球墨铸铁件消失模铸造技术

介绍了低温高韧性球墨铸铁电机端盖的消失模铸造工艺。低温球墨铸铁电机端盖模样采用EPS板材加工而成,EPS板材的密度18 g/dm~3,从泡沫模样的涂料涂刷与烘干,装箱造型等关键工艺控制变形;分析了消失模铸造生产低温球铁的原材料、化学成分选择、球化处理、孕育处理等工艺过程。结果表明,消失模铸造低温高韧性球墨铸铁电机端盖铸件力学性能、材质达到了同类产品先进的技术水平,电机端盖低温高韧度球墨铸铁件表面质量好,没有夹渣、加砂、冷隔、变形等缺陷,可批量生产。     

大型球墨铸铁中压外缸铸件的生产控制

介绍了大型球墨铸铁中压外缸铸件的结构及技术要求,为满足标准要求,从材料、铸件结构、设备设施等方面分析了该铸件的生产难点,从炉料选择、铁液预处理、孕育处理等方面阐述了中压外缸生产控制的重点。得出以下结论:(1)炉料的纯净与否对于大型厚断面球墨铸铁的生产非常重要,选择纯净炉料、控制微量干扰元素是生产高质量大型球墨铸铁件的首要条件;(2)加强对铁液冶金质量的控制,工艺上对可能出现的铸造缺陷采取相应的防止措施,可生产出满足技术要求的大型厚断面球墨铸铁件。     

风力发电机电机端盖低温球墨铸铁件的生产

介绍了低温高韧性球墨铸铁电机端盖的铸造工艺方案、工艺装备.分析了生产低温球铁的原材料、化学成分选择,球化处理、孕育处理等工艺过程.生产的电机端盖铸件力学性能、材质达到了同类产品先进的技术水平,可批量生产.     

球墨铸铁框架件的消失模铸造工艺

介绍了消失模铸造球墨铸铁框架件的研制经验,提出了消失模铸造球墨铸铁铸件控制的主要工艺参数,分析了铸件缺陷的形成原因.结果表明:采用底注式浇注系统和适当提高浇注温度可改善铸件表面质量,采用圆环形冒口可有效消除铸件缩松缺陷;用消失模铸造技术生产球墨铸铁框架类铸件,铸件表面质量高,成品率高,成本低,具有较好的经济效益.     

铁型覆砂球墨铸铁件凝固模拟及收缩缺陷预测

建立了铁型覆砂铸造凝固过程模拟的数学模型.采用动态膨胀收缩法(DECAM)和K*G/R判据预测球墨铸铁件的收缩缺陷,对球墨铸铁四缸曲轴新产品进行了模拟计算,根据模拟结果对原有工艺方案进行了改进,并在实际生产中得到了合格的铸件.结果表明,对铁型覆砂球墨铸铁件进行数值模拟和工艺优化,有助于提高铸件质量,缩短试制周期,降低工装费用.     

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。