用冷却曲线估测动态条件下淬火油的淬火烈度

对淬火油在不同流速下的冷却曲线和淬火烈度进行了测量 ,建立了硬化能力、淬火烈度与介质流速三者之间的关系。结果表明 ,淬火油的淬火烈度H值与建立在冷却曲线基础上的硬化能力HP值均随介质流速的增加而增加 ,二者增加的斜率相近。因此 ,在测得冷却曲线的前提下 ,可以估算出淬火油在该流速下淬火烈度的增加值     

淬火油冷却性能的评定方法

1.前言淬火油用于淬火操作过程中的冷却。淬火所采用的冷却剂,除了淬火油之外,还可用水、水溶性淬火剂、盐浴等。但就冷却性能的稳定、使用方便和处理成本来说,淬火油在冷却剂中仍占主导地位。以淬火油为主的冷却剂的冷却性能评定方法有 JIS 冷却性能测试法和ASTM 淬火表测定法等。我国通常采用前一种测试方法。因此,首先对用 JIS 测试法所测得的 JIS 冷却曲线加以说明,然后再对用 JIS 冷却曲线来判定淬火油的冷却性能时所需注意的问题等作进一步的说明。与此同时,为了得到稳定的淬火结果,需要将淬火油冷却性能的     

两种淬火油对板簧热处理质量影响的研究

通过对N32机油和今禹Y15-Ⅱ快速光亮淬火油的冷却特性的对比研究．以及对采用两种油进行的60Si2Mn和50CrVA钢样品淬火冷却后的组织性能分析，研究了两种油对板簧热处理质量的影响。实验结果表明，N32机油的高温冷却速度不足是其不适于有效厚度大于12mm的60Si2Mn板簧淬火的原因。而今禹Y15-Ⅱ快速光亮淬火油的蒸汽膜阶段短，高温冷却速度较快，有足够的低温冷却速度，能够满足14mm以下厚度的60Si2Mn和20mm左右50CrVA板簧淬火。     

动态淬火介质冷却特性及换热系数的研究

为了研究工业生产条件下淬火油在不同流速下的冷却特性曲线及换热系数 ,用超声波多普勒流量计测定了淬火油槽的流速 ,按ISO9950标准测定冷却特性曲线 ,用 1 2 0mm× 1 2 0mm× 2 0mm平板状试样和反传热法测定与计算了换热系数。结果表明 ,随着介质流速的增加冷却特性曲线的冷速最大值及换热系数的最大值均呈增加趋势 ,当搅拌使介质中产生气泡时 ,介质的冷却能力明显降低。最后指出换热系数曲线能更好地反映表面热量传递的真实情况。     

不同冷却方式下换热系数的测量与计算

为了研究不同冷却方式下的换热系数,设计了一套可以测量空冷、水淬以及不同压力下喷气淬火下冷却曲线的试验装置,试验中测量的探头采用120mm×120mm×20mm奥氏体不锈钢方板。该探头经有限元(FEM)计算验证了其一维传热特性后,用来测量上述几种冷却方式下的冷却曲线,并用反传热法(IHCM)和集中热容法(LHCM)进行换热系数的计算与分析,比较了不同压力下喷气淬火的换热系数。实验结果表明,当毕欧数Bi<0.1时集中热容法是适用的,反之则不适用;在喷气淬火时,压力越大,表面换热系数也越大。     

冷却性能的现场测试

淬火介质的生产厂家使用冷却曲线的方法测定淬火介质的冷却性能数据作为其出厂的标准，而绝大多数淬火介质使用厂家都难以用同样的方法验收和对淬火介质进行监测和维护。目前，要求所有使用厂家都安装冷却性能测试仪还有诸多不便之处。本文拟提出一种简易的现场测试方法。这种方法是以热处理炉的控温仪表作为测试冷却曲线数据的温度显示仪表。本文将以ＺＢＥ－４５００３“热处理油的冷却性能测定法”为例，讨论这种简易方法的可行性     

弹簧钢淬火残余应力模拟

对AISI 5160H弹簧钢圆柱试样在不同温度的25％水溶性聚(亚烷基)二醇UCONHT淬火液和Arco521淬火油中淬火产生的残余应力及畸变进行了对比性研究。试棒的直径分φ20．56mm(0．81 inches)和φ13．45mm(0．53 inches)两种。先用INC-PHATRAN代码计算出试样随时间变化的传热系数，并用ABAQUSA际准有限元软件估算热处理过程中的残余应力和畸变。在试样中心放置热电偶，测出冷却曲线，根据所测的冷却曲线，用INC-PHATRAN解决了伴随相变时的逆向热传导问题。试验了这两种淬火介质，力图将热处理畸变和开裂减少到最少,并得出了颇有价值的结论。     

冷却性能的现场测试

淬火介质的生产厂家使用冷却曲线的方法测定淬火介质的冷却性能数据作为其出厂的标准，而绝大多数淬火介质使用厂家都难以用同样的方法验收和对淬火介质进行监测和维护。目前，要求所有使用厂家都安装冷却性能测试仪还有诸多不便之处。本文拟提出一种简易的现场测试方法。这种方法是以热处理炉的控温仪表作为测试冷却曲线数据的温度显示仪表。本文将以ZBE－45003“热处理油的冷却性能测定法”为例，讨论这种简易方法的可行性，这样生产厂和使用厂将有“共同的语言”来对话。     

水在不同温度和流速下冷却能力的测量

为了研究水在不同温度和不同流速下的冷却特性,采用标准镍合金探头和淬火介质动态冷却特性测定仪,分别对水在不同温度和不同流速下的冷却曲线进行了测量,并对其冷却特性进行了定性分析和定量计算.结果表明:水温变化对水的冷却能力的影响明显高于流速变化对其的影响;静止水在水温60～70℃区间的冷却能力发生突变;水温和流速对水的冷却能力的影响可以用硬化能力值和冷却曲线面积定量表示.     

淬火液冷却性能的研究

近来,在国外对寻找淬火介质非常注意,这些新的淬火介质的特性处于水和油,之间,或兼有两者的优点。经典的方法是通过银质小球测定,并用照相纸记录冷却曲线来研究淬火介质的冷却性能,此方法应用在工厂条件下是不方便的。在哈尔科夫拖拉机厂采用直径20mm,厚度为3～6mm的镍质园盘代替银质小球     

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。