除镁工艺对除镁效果的影响

在试验的基础上分析了除镁剂的加入方式、除镁温度、保温时间、除镁剂的加入量等工艺条件对除镁效果的影响,总结出了最佳的除镁工艺.     

镁锂合金的塑性变形与断裂:研究进展与展望EI北大核心CSCD

镁锂合金在航空航天、国防军工以及电子技术等领域具有重要应用。本文主要回顾了国内外针对镁锂合金塑性变形及断裂失效的研究工作,简要介绍了适用于镁锂合金的塑性加工工艺,总结了各种塑性加工工艺对镁锂合金微观组织及力学性能的影响,并且系统论述了镁锂合金的塑性变形机制及断裂失效行为。最后,本文指出了现有塑性加工工艺在镁锂合金应用中的局限性,以及限制镁锂合金应用的因素,并对未来镁锂合金的研究方向及重点进行了展望。     

用低碳镁碳砖钢包冶炼低碳不锈钢生产实践

介绍了用低碳镁碳砖钢包VOD、VD工艺冶炼低碳不锈钢的试验情况,分析讨论了低碳镁碳砖对冶炼过程的影响。钢包精炼炉低碳镁碳砖VD工艺可冶炼C≤0.06%、VOD工艺可冶炼C≤0.04%的不锈钢。     

硅热还原炼镁工艺的发展探讨

本文介绍硅热还原炼镁工艺在炼镁工业中所处的地位,分析了目前硅热还原炼镁技术中存在的主要问题和潜在危机。并对硅热还原炼镁工艺在中国大陆可持续发展及对策进行了探讨。     

论我国电解法炼镁工业改造方向

简述了我国电解法炼镁工业进步,指出与国外的差距,提出用轻烧菱镁矿球团氯化改进现有氯化工艺必要性,采用卤水合成铵光卤石炼镁工艺组成联合流程,达到电解法镁厂内部氯气平衡,最后达到氯气可作为镁厂的一种产品出售,从而使电解法镁厂技术经济指标和装备水平接近或达到世界先进水平。     

喷镁球化在离心球墨铸铁管生产中的应用

铁水的球化是球墨铸铁管生产中的关键工艺,决定着产品的质量.概述了喷镁球化工艺的原理,介绍了实际生产中喷镁球化工艺的形式,阐述了喷镁球化喷吹系统装备的类型,提出了选用工艺和装备的原则.喷镁球化工艺在生产离心铸造球墨铸铁管中取得了良好效果,提高了铸管质量,降低了生产成本.     

镁生产厂房及各种设备的防腐工艺改进的浅谈

通过对镁冶炼系统防腐技术的评析,提出镁冶金厂房、设备、炉、槽,管道等有关防腐工艺的改进方案。该防腐方案投资费用少,防腐效果好,延长厂房,设备、炉、槽等使用寿命,可供新建镁厂以及旧镁厂防腐工艺改进作参考。     

镁电解车间工艺设计的实践

阐述了镁电解车间氧化镁电解及镁精炼工段工艺,所使用的主要设备及车间配置和对其它工艺的要求。设计建成投产后运行效果良好,受到一致好评。     

块状高电位Mg—Mn牺牲阳极熔铸工艺研究

进行了熔融粗镁直接熔炼高电位镁阳极短流程工艺、分层加热净化镁熔体技术、低压转注技术熔铸高电位Mg-Mn阳极的可行性试验.结果表明,新工艺获得成功,新工艺相对以精镁为原材料合金化人工浇注的普通工艺阳极具有能耗少、低成本、效率高的特点.扫描电镜照片和能谱分析表明,新工艺阳极组织中没有氧化夹杂和熔剂夹杂,而普通工艺制备的高电位Mg-Mn阳极组织中有少量这些夹杂.纯净的组织使新工艺生产的阳极电流效率平均比普通工艺阳极提高13.2%,开路电位提高2.3%.     

多极性新型镁电解槽技术的能耗分析研究

通过与110kA大型无隔板镁电解槽的对比,对多级性新型镁电解槽技术的日产镁量和吨镁能耗进行了探讨,结合该技术的工艺原理和特点,分析其原因。     

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。