铌钒氮微合金钢中碳氮化合物研究

将铌钒氮微合金钢进行热轧和空冷处理，透射电镜发现铁素体中弥散着细小的球形析出相，三维原子探针分析显示这些析出相为Nb、V、Mo碳氮化物，进一步研究表明V、Nb、Mo原子主要依次位于碳氮化物的中心、次中心层和外层，Mn原子在基体与碳氮化物界面处偏聚。从碳氮化物的中心到外层依次主要为V的碳化物、Nb的碳氮化物、Mo的碳化物。     

铌钒氮微合金钢中碳氮化合物研究

将铌钒氮微合金钢进行热轧和空冷处理,透射电镜发现铁素体中弥散着细小的球形析出相,三维原子探针分析显示这些析出相为Nb、V、Mdo碳氮化物,进一步研究表明V、Nb、Mo原子主要依次位于碳氮化物的中心、次中心层和外层,Mn原子在基体与碳氮化物界面处偏聚.从碳氮化物的中心到外层依次主要为V的碳化物、Nb的碳氮化物、Mo的碳化物.     

合金化高锰钢ZGMn13CrMo的组织与性能研究

通过对奥氏体高锰钢进行合金化和热处理工艺优化，研究了合金化高锰钢ZGMn13CrMo的力学性能、显微组织和耐磨性。结果表明，ZGMn13CrMo水韧处理后组织为奥氏体基体和均匀、细小、弥散分布的颗粒状碳化物。碳化物强化了奥氏体基体，冲击韧度是普通高锰钢的1．41倍，屈服强度是普通高锰钢的1.38倍，抗拉强度是普通高锰钢的1．25倍，耐磨性是普通高锰钢的1.35倍以上。     

一种改善耐磨高锰钢碳化物形态的热处理工艺

探讨一种改善耐磨高锰钢碳化物形态的热处理工艺。结果表明,水韧处理结合高压热处理和常压热处理可以有效地改善耐磨高锰钢组织中析出碳化物形态及分布,经水韧处理后再经5 GPa、650℃保温30 min的高压热处理和750～800℃保温60 min的热处理,耐磨高锰钢可获得弥散分布的颗粒状和短条状碳化物。     

扫描电镜分析合金碳化物对气缸套耐磨性的影响

一、前言铸铁气缸套的耐磨性主要取决于铸铁的金相组织。磷共晶、含硼碳化物、碳氮化物或合金碳化物都是气缸套中耐磨的硬质相。这些硬质相由于类型、显微硬度、分布、数量及其块度大小的不同,就造成了气缸套材质上耐磨性的差异。磷共晶和含硼碳化物已在文献中作过专门的介绍。因此,本文对它就不再作进一步叙述。本文作者通过硼钨铬多元合金铸铁、钒钛铸铁、铌铸铁三种不同材质气缸套中合金碳化物相的扫描电镜分析,对照这三种气缸套与国内广泛使用的高磷合金铸铁、硼铸铁气缸套,在同一条件下的快速磨损对比试验。提出了影     

HRB500E微合金化钢筋中钒的化合物析出行为

分析了HRB500E微合金化高强度钢筋中钒的氮化物、碳化物和碳氮化物分别在液相、凝固过程、奥氏体以及铁素体相中的析出热力学条件，并研究了它们在实验钢连铸或热处理过程中的析出规律。结果表明：实验钢中，钒的碳化物和氮化物在钢液中不析出。碳氮化钒(VC_xN_1-x)中的x值随温度降低而增大，即在高温平衡条件下析出富氮的碳氮化物，在全固溶温度1450 K下析出物为VC_0.03N_0.97。VN在1176～1448 K温度区间内在奥氏体相中析出，温度低于1176 K时，主要析出物为碳化钒或碳氮化钒。实验钢铁素体相中也观察到有钒的化合物析出，呈椭圆形，析出规律与热力学分析结果基本吻合。     

高锰钢低温时效处理时的组织结构

采用金相和X射线衍射分析方法研究了不同低温温度及其保温时间对经水韧处理的高锰钢组织结构的影响规律。结果表明：在保温时间为1h时，高锰钢基体在500℃时开始有针状碳化物的析出；而在600℃时除了有针状碳化物的析出之外，还有珠光体组织的出现。在低温时效处理温度为600℃时，随着保温时间的延长，高锰钢基体中奥氏体的量减少，而珠光体的量增加。在500℃时效处理时，沿晶界形核并向晶内生长的针状碳化物与母相奥氏体之间的位向关系和在晶内析出的针状碳化物的不同：以及在晶内析出的针状碳化物可以交叉生长。这种针状碳化物交叉生长的形态在钢的组织转变中还尚未见有文献报道．     

不同稀土加入量对高锰钢组织及力学性能的影响

对不同稀土加入量的高锰铸钢采用电子式万能试验机测试拉伸性能,进行金相显微组织观察和SEM及EDS分析。结果表明:将稀土加入高锰钢中,能细化晶粒,改变碳化物的形态与分布,使碳化物呈颗粒状弥散分布,从而有效改善高锰钢的强度与塑韧性。     

加钛和氮对结构钢加热时奥氏体晶粒长大的影响

钢的物理性能和机械性能,在很大程度上决定于奥氏体晶粒的尺寸。大家知道,晶粒尺寸本身决定于钢的成份,变形规范和热加工。钢中细小的氮化物、碳化物,碳氮化合物以及其它夹杂物对晶粒长大起着重要的影响。中碳碳素钢用铅脱氧时,加入钛和氮可形成氮化物、碳化物和钛碳氮化合物,根据这些化合物形成的自由能数据,可假设,首先钢中应当析出氮化钛。资料指出:一般形成的不是纯的氮化物,而是碳和氮比值不同的钛碳氮化合物,等前提是TiC     

能谱和能量损失谱在半高速钢碳氮化物分析中的应用

合金总量为12%的两种Cr-W-Mo-V系半高速钢试验材料,其中一种添加0.05%～0.1%氮元素进行合金化,试样经950～1 050 ℃淬火后分别再经100～600 ℃两次回火.采用透射电镜（TEM）、扫描电镜（SEM）及能谱仪（EDS）和能损失谱（EELS）对碳化物形貌和成分进行分析,分析淬火加热时及回火过程中的碳化物数量和成分的变化规律.试验结果表明：加氮半高速钢的氮化物中含有较多的钒、钨、钼和较少的铬元素,淬火加热时表现出较高的稳定性;氮促进碳氮化物在425～475 ℃回火时析出,在550 ℃回火时碳化物依附在氮化物表面沉淀形成复合碳氮化物.     

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。