塑料挤出机头中熔体流动的均匀性分析

根据塑料熔体流变学理论,推导了中空异型材挤出机头中塑料熔体流动的均匀性公式,提出了采用变厚流道法和过渡线法来提高熔体流动均匀性的两种途径,最后通过计算机对实例进行了可行性验证,为中空异型材挤出机头设计提供了较为实用的方法。     

塑料异型材挤出模模头熔体压力分析

根据U-PVC的熔体特性,确定U-PVC熔体为非牛顿流体,引入拉比诺维茨修正的哈根-伯肃叶公式,介绍了塑料异型材挤出模模头的熔体压力理论分析方法和模头流道压力计算方式,对熔体压力在模头中流道的分布和影响压力分布的要素进行分析,通过与生产过程中所测熔体压力数据进行对比,确定该压力计算方法的准确性,为U-PVC塑料异型材挤出模头的熔体流道压力的设计提供理论依据。     

Fe—Mn—C—P系高锰熔体的热力学研究

测定了１４００℃时Ｆｅ－Ｍｎ－Ｃ－Ｐ系高锰熔体中碳的溶解度为Ｎｃ＝０．１９６１＋０．１１８３ＮＭｎ－０．８５２５Ｎｐ；计算得到Ｍｎ与Ｃ，Ｐ与Ｃ的活度相互作用系数为：εＣ＾Ｍｎ＝－１．６７，ρｃ＾Ｍｎ＝０．２９，εｃ＾ｐ＝１１．００，ρｃ＾ｐ＝１０．８２；估算了高锰熔体中Ｍｎ，Ｐ和溶剂铁的活度系数。     

Fe－Mn－C－P系高锰熔体的热力学研究

测定了１４００℃时Ｆｅ－Ｍｎ－Ｃ－Ｐ系高锰熔体中碳的溶解度为：Ｎ＿Ｃ＝０．１９６１＋０．１１８３Ｎ＿（Ｍｎ）－０．８５２５Ｎｐ；计算得到Ｍｎ与Ｃ，Ｐ与Ｃ的活度相互作用系数为：ε＿Ｃ￣（Ｍｎ）＝－１．６７，ρ＿Ｃ￣（Ｍｎ）＝０．２９，ε＿Ｃ￣Ｐ＝１１．００，ρ＿Ｃ￣Ｐ＝１０．８２；估算了高锰熔体中Ｍｎ，Ｐ和溶剂铁的活度系数。     

刃口钢抗钝化＜效的宏观力学判据的研究

本文根据大量实验数据提出了一个表征钝化失效规律的定量公式：ｔ＝ｎ·Ｎ＋ｔ其中ｎ为刃口钢的钝化系数，ＳＰ＝ｌ／ｎ，定义为本质锋利度，可作为衡量刃口材料抵抗钝化失效新的力学性能指标。通过对淬火＋回火的ＧＣｒ１５钢、４５钢和６０钢钝化规律的研究，求得了它们的ｎ值，并阐明了锋利度及钝化系数的物理意义及技术意义。     

一种测定非晶形成合金熔体粘度的方法

提供了一种测定非晶形成合金熔体粘度的方法,用覆盖渣保护合金不受氧化,应用旋转柱体法测得了Zr50Cu50合金熔体的粘度-温度曲线。测量结果表明:在1373～1233K温度范围内,随着温度的下降,Zr50Cu50合金熔体粘度呈指数增加,基本符合Arrhenius公式。但在1233K以下,明显不符合Arrhenius公式,粘度值骤然上升,至液相线温度粘度值达到了2.415Pa.s;Zr50Cu50合金熔体粘度比其他合金熔体粘度要高3个数量级;分析认为,合金熔体粘度大有利于非晶形成能力的提高。     

三元系金属熔体中的活度和活度相互作用系数模型

提出计算金属液中活度和活度相互作用系数的模型．据此可以快速、准确地计算出任何三元系金属熔体中除Ｏ，Ｓ，Ｓｅ，Ｔｅ外任何组元的１ｎγ和任何组元间的一级活度相互作用系数ε，ε以及二级活度相互作用系数ρ，ρ，ρ．影响１ｎγ的因素是ｉ（溶质）和ｋ（溶剂）的ｎＷＳ（电子密度）、Φ（电负性）以及ｉ的Ｖ（摩尔体积）值。由模型计算出的１ｎγ值与实验值吻合较好，对铁基合金正负号一致率达９５．７％；影响活度相互作用系数的因素是溶质ｉ和ｊ以及溶剂ｋ的ｎＷＳ，Φ和Ｖ，ε，ε的计算值和实验值基本一致，对液态铁合金正负号一致率达８０％以上．     

三元系金属熔体中的活度和活度相互作用系数模型SCIEI

提出计算金属液中活度和活度相互作用系数的模型．据此可以快速、准确地计算出任何三元系金属熔体中除Ｏ，Ｓ，Ｓｅ，Ｔｅ外任何组元的１ｎγ和任何组元间的一级活度相互作用系数ε，ε以及二级活度相互作用系数ρ，ρ，ρ．影响１ｎγ的因素是ｉ（溶质）和ｋ（溶剂）的ｎＷＳ（电子密度）、Φ（电负性）以及ｉ的Ｖ（摩尔体积）值。由模型计算出的１ｎγ值与实验值吻合较好，对铁基合金正负号一致率达９５．７％；影响活度相互作用系数的因素是溶质ｉ和ｊ以及溶剂ｋ的ｎＷＳ，Φ和Ｖ，ε，ε的计算值和实验值基本一致，对液态铁合金正负号一致率达８０％以上．     

注射模塑料熔体的刚度计算

注射模塑料熔体的刚度计算浙江宁波机械工业学校（浙江宁波３１５０１０）林裕华董明高１引言本文讨论的不是注射模的机械刚度（如模具侧壁、模板的刚度），而是塑料熔体的刚度、锁模系统油液的刚度。虽然多数场合，熔体与油液看成是不可压缩的，但在塑料注射成形时，熔体...     

注塑过程的数值模拟

针对塑料熔体的特性建立数学模型，并根据实际情况对有限元模型进行简化：采用大型有限元分析软件ANSYS对注塑模的瞬态注塑过程进行数值模拟，得到塑料熔体在型腔中的速度分布和压力分布；通过不同工艺参数条件下的结果进行对照分析，可以对工艺参数做出合理的选择；实验表明，该数值模拟法确实能对塑料注射过程的参数进行优化，为设计塑料注射过程工艺参数提供了一种行之有效的途径。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.