ADI的疲劳性能

发动机曲轴和齿轮的失效形式属于疲劳失效,因此,疲劳性能是应用ADI曲轴、齿轮首先要考虑的性能.根据破坏原因,曲轴的疲劳强度计算应当是计算连杆轴颈圆角处的最大疲劳强度.齿轮的疲劳强度计算则有两种：齿根部弯曲疲劳强度计算和齿面接触疲劳强度计算.球铁的旋转弯曲疲劳强度随抗拉强度提高而增加,但不呈线性关系.奥氏体-贝氏体型球铁的疲劳强度达到或接近部分碳钢、合金钢经调质处理后的疲劳强度.喷丸处理可以提高ADI的各种疲劳强度.为了提高疲劳强度,抗拉强度与伸长率应合理地配合.     

17Cr2Ni2MoVNb和20Cr2Ni4A钢齿轮渗碳质量与弯曲疲劳寿命的试验研究

通过金相检测和显微硬度测试等手段,对17Cr2Ni2MoVNb钢齿轮和20Cr2Ni4A钢齿轮的渗层、心部组织、晶粒度及渗层深度等渗碳处理质量进行分析,并采用PLG-300C拉压疲劳试验机对上述两种材料齿轮进行弯曲疲劳寿命测试。结果表明,齿轮加载齿根处有效渗层深度和显微硬度是齿轮弯曲疲劳寿命的主要影响因素,相同载荷条件下加载齿根处有效渗层深度减小,轮齿弯曲疲劳寿命明显缩短;加载齿根显微硬度增大,轮齿弯曲疲劳寿命提高。渗层表面出现浅层脱碳层时(齿根脱碳层≤0.2 mm),虽然会降低轮齿的弯曲疲劳寿命,但相比加载齿根处的渗层深度和表面硬度,脱碳层的影响并不明显。     

贝氏体等温淬火球铁齿轮的弯曲疲劳强度

本论文研究了贝氏体等温淬火球铁[ADI]齿轮的弯曲疲劳强度,对ADI、S45C(类似我国45钢)、FCD80(0_2≥80)以及表层硬化SCr420(类似我国的20G)齿轮做了弯曲疲劳试验,把ADI齿轮同其它齿轮弯曲疲劳极限载荷作了比较。ADI齿轮几乎等于表面硬化齿轮的弯曲疲劳强度。而且还对ADI齿轮进行了喷丸,通过弯曲疲劳试验考察了ADI齿轮疲劳强度。喷丸可以显著地提高ADI齿轮的弯曲疲劳强度。关键词:齿轮、疲劳、弯曲、贝氏体等温淬火球铁、弯曲疲劳强度、喷丸、正齿轮,斜齿轮。     

用非表面强化方法提高铸态球铁曲轴的可靠性

在不采用圆角滚压等表面强化处理的条件下，为使铸态球铁曲轴的弯曲疲劳强度和耐磨性达到技术要求，采取了三个措施：（1）通过合金化和优化铸造工艺，使强度和韧性达到最佳匹配；（2）加大连杆轴颈与曲柄臂的过度圆角；（3）增大曲柄臂的厚度，曲轴弯曲疲劳弯曲强度对比试验和300h台架可靠性试验以及25000km道路试验均证明，采用上述措施制造铸态球铁曲轴的方案既降低曲轴成本，又能使曲轴具有足够的弯曲疲劳强度。     

工艺因素对球铁曲轴疲劳性能的影响

对经正火、气体氮化、圆角滚压三种工艺的球墨铸铁曲轴进行弯曲疲劳试验，测出其疲劳极限M-1(50％)分别为1471、1935和3010N-m。说明了采用气体氮化工艺的球铁曲轴疲劳强度比正火态提高31％；而采用圆角滚压工艺的球铁曲轴疲劳强度比正火态提高104％。     

奥贝球铁材料接触疲劳强度的研究

奥贝球铁材料的弹性模量比钢小，因而奥贝球铁齿轮工作时受到的表面接触应力比钢齿轮小。奥贝球铁材料的接触疲劳应力可达1426MPa以上，高于280hp柴油机齿轮的接触应力，因此用奥贝球铁代替调质氮化钢生产280hp柴油机齿轮是完全可能的。     

齿间摩擦对机床增速齿轮传动中惰轮齿根弯曲疲劳的影响

本文系统地研究了影响机床增速齿轮传动中惰轮齿根弯曲疲劳的诸因素。并推导出包括齿间滑动摩擦在内的实际外载荷作用下惰轮齿根弯曲疲劳应力计算公式。研究表明,齿间摩擦对机床增速齿轮传动中惰轮齿根弯曲疲劳强度的影响不可忽视。     

奥贝球铁磨粒磨损性能的研究

奥贝球铁磨粒磨损性能的研究郭新立，孟祥康，刘治国，董鄂（南京大学）（南京理工大学）奥贝球铁是新一代的球墨铸铁，与普通球铁相比，奥贝球铁具有较高的强度、韧性、抗点蚀疲劳、弯曲疲劳和耐磨性能，被视为７０年代以来铸铁冶金的重大突破￣［１、４］。其应用目标之...     

X105系列柴油机球铁曲轴的热应力强化

本文介绍了利用热胀冷缩原理,在球铁曲轴轴颈表层获得压应力,提高曲轴的疲劳强度的热应力强化工艺。对球铁曲轴经热应力强化处理后,残余应力的稳定性、疲劳强度的提高和曲轴的变形等进行了分析讨论。弯曲疲劳试验的结果表明,X105系列柴油机曲轴,经过热应力强化处理,其弯曲疲劳强度可提高50％。由此,我们认为热应力强化法是一种新的有效的球铁曲轴强化方法。     

奥贝球铁齿轮在柴油机上的应用研究

研究了不同等温温度及Mn、Si、Cu、Mo对奥贝球铁组织和力学性能的影响,讨论了奥贝球铁加工硬化对机加工性能的影响。同时,奥贝球铁齿轮代替40Cr调质钢齿轮进行装机试验,对降噪声和耐磨性进行了测试。结果表明,奥贝球铁齿轮与40Cr调质钢齿轮相比,力学性能高,柴油机整机噪声下降1.92dB,齿轮侧噪声下降5.3dB,奥贝球铁齿轮经过45h磨合后,在标定工况下连续运转200h,齿轮无异常磨损,齿轮间隙离极限间隙还有0.13mm的余量,所以其摩擦磨损性能合格,所生产的奥贝球铁齿轮满足设计使用要求。     

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。