30CrMnSiA钢激光相变硬化层组织

对30CrMnSiA钢进行了激光相变硬化处理，研究了相变层的组织和硬度特征。试验结果表明，30CrMnSiA钢表面相变硬化层分为完全淬硬层、过渡层和受热影响的基体组织，硬化层的显微组织明显细化，其表面层的硬度高达(685～775)HV，比高频淬火的硬度提高了30％。     

激光扫描速度对45钢表面改性层组织及性能的影响

利用横流CO2激光加工机对正火态45钢表面进行激光相变处理,对改性层进行了OM实验、硬度测试以及硬化层磨料磨损实验.结果表明:相变硬化层由表及里依次为熔凝区、相变硬化区、过渡区和基体区;其中激光熔凝区晶粒最为细小;硬化层表面最高硬度为48 HRC;激光扫描速度对表面耐磨性有较大影响,其中扫描速度为8mm/s、功率700 W时改性层耐磨性最佳.     

扫描速度对硼铸铁气缸套表面钨极氩弧硬化效果的影响

研究了钨极氩弧扫描速度对硼铸铁表面硬化效果的影响规律。结果表明：扫描速度增加。硬化层宽度、深度减小，而硬度提高，裂纹率增大；硬化层硬度沿层深的分布是从表及里由高而低，在过渡区下降缓慢；沿层宽的分布是层中心最高。向两侧逐渐降低，直至硼铸铁基体达到最低值；在保证不出现裂纹的条件下，硬化层表面的最高硬度值可达61．4HRC，硬化层最高显微硬度值可达1156．4HV0．1；硼铸铁材料采用氩弧热源淬火时。淬硬层与基体之间过渡区明显，硬化区组织为莱氏体，过渡区为马氏体、残余奥氏体和少量石墨。     

TC4 钛合金真空脉冲渗氧硬化层的组织与性能

采用真空脉冲渗氧的方法,在TC4钛合金表面制备了与基体结合良好的硬化层,并对硬化层的组织结构、硬度、脆性等进行了分析。结果表明:硬化层由表面氧化物层和氧扩散区组成,氧化层中TiO2发生了分解,氧向基体内扩散,氧化层主要由α-Ti、金红石TiO2、TiO及少量Ti3Al组成,表层组织致密,表面硬度为650～670HV,硬化层深度可达60～80μm;此外,由于扩散区氧的固溶强化作用,硬化层的硬度梯度平缓,脆性小。     

等离子改性工艺对含硼铸铁组织和性能的影响

针对柴油机气缸套磨损失效现象，采用高能等离子束在常压下快速扫描含硼铸铁气缸套内表面，对缸套内壁进行局部硬化改性处理，获得了高硬度淬火硬化层，分析了等离子改性对硼铸铁汽缸套表面组织的影响，研究表明，工作电流越大、扫描速度越低，硬化区表层残余奥氏体含量越少；在扫描速度不变的情况下，工作电流越大，硬化层深度越大、硬度越高；工作电流不变，扫描速度越低，硬化层深度越大、硬度越高。通过磨损实验对比，可知等离子硬化后的硼铸铁的耐磨性高于含硼铸铁基体，而含硼铸铁基体的耐磨性又高于灰铸铁。     

TB8钛合金间歇式真空气体渗氮层的组织与耐磨性（英文）

为了提高耐磨性,对TB8钛合金进行间歇式真空气体渗氮处理。利用XRD和SEM分析了改性层的物相组成和显微组织,并对改性层的表面硬度和耐磨性进行了研究。结果表明,TB8钛合金经800℃间歇式真空气体渗氮4 h后,表面改性层物相主要由TiN、TiN_(0.3)、Ti_2AlN及α-Ti组成,渗氮层组织致密,与基体结合良好,表面HV硬度为8.50～9.0 GPa,是基体硬度的3倍,硬化层厚度为100～120μm。由于表面形成的硬化层较深,故耐磨性得到了极大改善。     

大功率半导体激光相变硬化U74轨钢的试验

使用自制的大功率半导体激光器对U74轨钢进行了相变硬化.结果表明,硬化层硬度值可以达到800～900 HV0.01,是基体硬度的3～4倍,沿半导体激光器光斑的不同轴向扫描对硬化层有很大影响,沿慢轴方向扫描得到的硬化层深度要远高于快轴方向,硬度值沿深度方向在过渡区附近迅速下降至基体硬度.试验表明,大功率半导体激光器在材料表面处理领域有着较为广阔的应用前景.     

球墨铸铁QT600-3激光相变硬化试验研究

采用CO2激光对模具材料球墨铸铁QT600-3进行激光相变硬化的试验研究。结果表明,在较大光斑直径,较低的激光功率密度,较低激光扫描速度的工艺条件下,激光扫描后的硬化层组织中含有较多的针状马氏体;硬化层表面的宏观硬度可达60HRC,为基体硬度的2.4倍,硬化层表面处的显微硬度随着扫描速度的减小而增大,随着激光功率的增大而增大。硬化层深度可达到0.95 mm,硬化层的深度随着扫描速度的增加而减小,随着激光功率的增加而略有增加。     

TB8钛合金间歇式真空气体渗氮层的组织与性能

为了提高表面硬度和耐磨性,对TB8钛合金进行间歇式真空气体渗氮处理。利用XRD和SEM分析了改性层的物相组成和显微组织,并对改性层的表面硬度和耐磨性进行了研究。结果表明,TB8钛合金经800 ℃间歇式真空气体渗氮4 h后,表面改性层物相主要由TiN、TiN0.3、Ti2AlN、及α-Ti组成,渗氮层组织致密,与基体结合良好,表面硬度为900-950HV,比基体硬度提高了近3倍,硬化层厚度为80-100 μm,由于表面形成了梯度硬化层,耐磨性得到了极大改善。     

球墨铸铁凸轮轴的激光表面熔凝处理

分析了激光表面熔凝处理后球墨铸铁凸轮轴硬化层的组织和性能特点，并与其它强化方法进行了比较。结果表明，采用适当的激光表面熔凝处理工艺参数，可以在表面获得搭接均匀、表面硬度大于80HRA和厚度达1．0mm的硬化层；硬化层由熔凝层和淬硬层组成，其中熔凝层的基体组织主要为细小、均匀并且有一定方向性的亚共晶莱氏体，淬硬层主要由石墨球及其周围的硬质环、细马氏体和铁素体基体所组成。与其它铸铁凸轮轴强化方法相比，激光表面熔凝处理具有表面硬度高、组织细小均匀、零件畸变小和不影响心部性能等优点。     

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。