潮湿空气环境对预腐蚀铝合金疲劳性能影响研究

采用预腐蚀铝合金7XXX应力集中系数为Kt=1和Kt=3试件进行了试验室空气环境和潮湿空气环境下的疲劳寿命试验及升降法试验,研究了潮湿空气环境对预腐蚀铝合金7XXX疲劳性能的影响。结果表明:潮湿空气环境显著降低了预腐蚀铝合金7XXX的疲劳性能,当假设疲劳强度服从正态分布时,潮湿空气环境对预腐蚀铝合金7XXX疲劳强度均值的影响系数分别为0.968(Kt=1)和0.941(Kt=3),安全寿命是试验室环境的18.38%(Kt=1)和28.94%(Kt=3),在潮湿空气环境中疲劳寿命的分散性变大,潮湿空气环境对服从双参数威布尔分布疲劳寿命特征值和规定置信度、可靠度寿命值的腐蚀影响系数,分别为0.785 3(Kt=1),0.669 4(Kt=3)和0.183 8(Kt=1),0.289 4(Kt=3)。     

硼对铸铁的作用及对硼碳化物的认识

72年起国内开始研究硼铸铁,77年12月硼铸铁汽缸套在上海鉴定通过,证明其耐磨性比高磷缸套可以提高50%,建议推广使用。现在硼铸铁除在汽缸套上应用外,并且在机床导轨上、空心水泥板挤压机的螺     

铍青铜在压铸冲头中的应用

叙述了影响压铸冲头寿命的各种因素及改进方法,特别对用于压铸冲头的铍青铜材料选择和提高铍青铜产品质量的措施进行了介绍.通过真空熔炼和添加0.2%的稀土Nd后,铍青铜的伸长率得到了较大的改善,高铍青铜(1.9%～2.0%的Be)由2%～5%提高到9%,低铍青铜(0.45%～0.55%的Be)由8%～13%提高到19%.实际使用中,与球墨铸铁冲头寿命相比,低铍青铜冲头寿命提高了5倍,高铍青铜冲头寿命提高了10倍,综合效益非常显著.     

日开发直喷式汽车发动机

日本本田、三菱两家大汽车公司最近在开发直喷式汽车发动机方面取得一一fM著进展。其开发的新式直喷式发动机在节约燃油、油效利用上比传统的发动机提高f3（）Cu自喷式汽车发动机与传统的发动机相比，有许多优点。传统的汽车发动机是先将燃油经进口问向上喷人化油器，与空气混合后喷进汽缸，而直咬式发动机是将燃油直接喷人汽缸。传统的发动机是燃油和空气的混合燃气在汽缸活塞的往复运动中被压缩；而直喷式发动机是空气在汽缸里被压缩之后，燃油再由一个高压油泵打人汽缸，这就使燃气的补充分开了层次，在火花塞周围制造了一个充足的混合…     

基于无偏灰色马尔可夫链组合模型的管线腐蚀剩余寿命预测

压力管线腐蚀剩余寿命预测研究对防止管线泄漏和制定管线的合理检验策略具有重要意义。针对压力管线腐蚀检测数据量少且随机性大的特点,基于传统灰色GM(1,1)模型建立无偏灰色GM(1,1)模型提高预测精度,之后以此为基础构建无偏灰色马尔可夫链组合模型进行腐蚀剩余寿命预测。最后通过对某海洋油田原油处理系统管线腐蚀数据的算例分析,验证所建立模型精度并预测管线腐蚀剩余寿命。预测结果表明:该管线在使用8a左右将达到5级泄漏腐蚀状态,需进行大型检修,无偏灰色马尔可夫链组合模型的预测精度高于94%,预测精度符合工程问题的精度要求,说明此模型可用于中长期存在随机扰动的管线腐蚀剩余寿命预测。     

气液增力缸测试系统设计

针对高端气液增力缸的研发问题,以自主研制的气液增力缸为例,结合气液增压原理并基于NI数据采集卡与LabVIEW软件开发气液增力缸综合测试系统;测试结果与理论值的误差在5%之内,并进行了不确定度的计算,表明了测试结果的可靠性,同时提出基于测试系统的寿命测试方法。     

预合金粉在金刚石工具中的应用研究

预合金粉的品种繁多,性能可设计、调节范围极其广大,适用于多种金刚石工具,满足各种使用条件,可用于多种生产工艺流程,用户只需通过调节金刚石的品级、浓度、粒度,即可调配出各种用途性能的胎体,节省金刚石制品的研发费用,节约能耗,提高生产效率。实验结果表明:预合金配方粉可提高胎体抗弯强度18%,扩大了烧结温度的范围,提高了锯片切割寿命48%。     

含缺口TC21钛合金腐蚀疲劳性能分析

研究了TC21钛合金缺口试样在两种腐蚀环境（油箱积水、3.5%NaCl水溶液）与室温空气环境下的疲劳性能与断裂机理。并与光滑试样在室温空气环境下疲劳性能进行对比。结果表明,室温空气环境下,当两种试样疲劳寿命均达到5×105次循环时,缺口试样的循环应力值较光滑试样下降了52.7%;相同环境下随着应力水平降低,试样疲劳寿命增加;相同应力条件下,3.5% NaCl水溶液环境下试样疲劳寿命最低,油箱积水环境下次之,室温空气中TC21钛合金试样疲劳寿命最高;当应力较低时,差异更为显著。在腐蚀环境下,溶液中离子与金属原子发生电化学反应,加速了裂纹的萌生与扩展,3.5% NaCl水溶液中离子浓度较大,电化学反应更为剧烈     

带有空气预热装置的圆形燃油加热炉

由生产需要,我们设计了一台带有空气预热装置的圆形燃油加热炉。经数年的使用表明,该炉节省燃料、升温快、炉门不冒烟、操作方便,并可用来进行少无氧化加热。现将其结构及使用情况介绍如下:     

聚四氟乙烯活塞环在锻锤上的应用

聚四氟乙烯塑料活塞环在锻锤上的应用,已引起越来越多的工厂的注意。我厂自8O年代初就开始了试用。实践证朗:使用效果良好,比钢制活塞环效果更佳,是值得推广的。使用聚四氟乙烯塑料活塞环可以大大地减少汽缸套的磨损和拉伤,从而显著地增加汽缸     

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).     

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.     

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.     

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。