铸坯热送热装工艺对加热炉能效的影响

为了探究热送热装工艺的节能优势,本文以某钢厂热送热装生产线为研究对象,通过测量铸坯温度、收集连铸坯生产参数,建立了铸坯在炉加热模型,利用有限元法计算了铸坯的温度云图分布和热量变化情况,比较了不同热履历铸坯在炉加热过程中的异同。同时,测量了不同装炉温度下的加热炉炉况,结合加热炉各段温度、空煤气流量、烟气流量等生产参数与铸坯吸热量的数值模拟计算结果,分析了不同装炉温度下加热炉的热平衡和燃耗。研究表明:相较于冷装,现有热装加热工艺可减少燃耗约11.81 kgce/t;通过调节生产节奏,解决了现有热送热装工艺存在的铸坯在炉时间过长的问题,优化后的工艺较冷装吨钢生产可节省燃耗约19.62 kgce/t。     

等径道角挤压制备高力学性能细晶Mg-6Al合金

为了制备高力学性能细晶Mg-6Al合金坯料,采用金相显微镜、材料拉伸实验机等手段对Mg-6Al合金铸坯进行等径道角挤压实验研究.并利用热处理工艺对挤压后材料进行处理,研究热处理工艺参数对材料力学性能的影响规律.结果表明,Mg-6Al合金的铸坯的抗拉强度为196.4MPa,延伸率为12.6%.经过等径道角挤压的Mg-6Al合金坯料的晶粒被大大细化,其晶粒尺寸由铸坯的140μm左右细化到8μm左右.其力学性能有很大提高,抗拉强度由196.4MPa提高到308.2MPa;延伸率由12.6%提高到30.6%.等径道角挤压工艺是一种非常好的制备高力学性能、细晶Mg-6Al合金的工艺方法.固溶和人工时效热处理工艺对等径道角挤压的Mg-6Al合金坯料的强度有较大影响,对延伸率影响较小.     

铸旋轮毂热旋压过程的数值模拟及工艺优化

为了优化铸旋铝合金轮毂的生产工艺,基于旋压变形的特点,建立了铸旋铝合金轮毂三旋轮热旋压复杂过程的三维有限元模型.采用所建立的有限元模型对实际的A356合金轮毂铸坯热旋压过程进行了数值模拟,对旋压载荷进行了分析,为旋压设备的选择和模具设计提供了依据;同时研究了铸坯开口角和旋轮轨迹分别对轮辋和内轮缘处应变分布的影响规律,获...     

Ti–43Al合金薄板连铸过程的数值模拟及微观组织预测

目的 研究真空条件下Ti–43Al合金在连铸过程中的传热特性及其微观组织特点。方法 通过ProCAST铸造仿真软件,基于非稳态连铸计算模型建立了连铸过程的温度场模型,获得了连铸板材在凝固过程中的温度场及其固相率的分布规律,并采用CAFE计算模块对连铸板材的微观组织结果进行了预测。结果 连铸坯表面与结晶器接触的位置温度下降速度较快,熔池的深度在整个连铸过程中处在较为合理的水平上;连铸板材两侧表面的细晶区非常狭窄,并形成了由板材表面向板材心部生长的柱状晶区,在靠近铸件心部的位置发生了CET转变。结论 越靠近铸坯心部,温度梯度和过冷度越小,越有利于发生CET转变,使铸坯由外生长转变为内生长。数值模拟预测所得的结果与验证实验结果吻合得较好。     

硼微合金化钢铸坯表面横裂纹产生原因及改进措施

某公司生产的硼微合金化钢铸坯表面出现了严重的横裂纹。采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析、热塑性分析等方法研究了该铸坯裂纹产生的原因。结果表明：铸坯的碳元素含量过高、铸坯的二次冷却制度不合理、铸机拉坯速率较低及铸机设备精度控制不当等因素导致铸坯表面产生横裂纹。采用优化原材料化学成分、提高拉坯速率、控制铸机精度等方法可以避免铸坯产生横裂纹。     

氮合金化HRB500E钢筋连铸传热过程模拟及配水工艺优化

建立了氮合金化HRB500E连铸坯的凝固传热数学模型,并通过有限差分方法求解传热微分方程;运用Matlab软件进行铸坯凝固传热模拟及仿真计算,分析了原有冷却制度的不合理性,并基于相关冶金准则进行了优化;通过回归分析确定了优化后各冷却区的动态配水关系式。研究表明,原有配水工艺冷却强度偏大,易造成铸坯裂纹及疏松等缺陷;经过优化后将结晶器冷却水量下调15%～20%,二冷区0段和1段冷却水量下调4%～15%,二冷区2段和3段冷却水量下调30%～55%。采用优化后的冷却制度生产的铸坯角部、边部、中心无任何裂纹,并且偏析和疏松在1.5级以内,铸坯质量得到明显改善,验证了模型的可靠性及工艺优化的合理性。经回归分析后的动态配水关系式拟合度良好,对氮合金化HRB500E连铸生产有指导意义。     

Monel400合金热压缩变形流变应力本构方程

目的研究Moenl400合金的热变形流变行为,确定合金热压缩变形的流变应力本构方程。方法在Gleeble1500热模拟机上对Ni-Cu固溶体单相合金Monel400进行等温热压缩实验,研究Monel400合金在变形温度为1173~1423 K、应变速率为0.01~10 s~(-1)时的流变应力;Monel400合金的本构模型为含有ZenerHollomon参数的双曲正弦函数模型,通过回归分析获得了材料常数Q,ln A,n,α与真应变ε的关系;并对不同变形条件下的实测值与计算值进行对比。结果 Moenl400合金的流变应力随温度的升高和应变速率的降低而降低;Moenl400合金流变应力的计算值与实验值吻合较好。结论通过计算得到的本构模型能够较好地表征Monel400合金的高温流变特性。     

含铌、钒、钛微合金钢连铸坯角部横裂纹研究现状

在微合金钢连铸生产过程中,角部横裂纹一直未得到有效解决,裂纹的存在减少了铸坯热送量,严重影响生产顺行。综述了微合金连铸坯角部横裂纹的形成机理,重点分析了铌、钒、钛等微合金元素对角部横裂纹的影响,分析了防止横裂纹产生的措施,认为消除微合金钢连铸坯角部横裂纹的最有效方法是控制铸坯表层微观组织,使其具有较低的裂纹敏感性,克服连铸弯曲与矫直过程中产生的应力,而不产生裂纹。     

异型坯结晶器与铸坯热力耦合数值模拟

为研究异型坯连铸结晶器内铸坯凝固和变形过程,采用ABAQUS软件建立了异型坯连铸结晶器和铸坯的二维瞬态热力耦合有限元模型,编制ABAQUS用户自定义子程序GAPCON实现结晶器内壁和铸坯之间的传热模拟.计算模型中考虑了铸坯的凝固和热变形、气隙对传热的影响以及铸坯与结晶器之间的接触应力.分别对2种不同水缝设计结晶器进行了数值模拟,数值分析结果表明,小孔水缝设计的结晶器温度峰值较低、热面温度分布更均匀,因而比大孔水缝设计结晶器具有更长的使用寿命和更优的铸坯质量,这一结论与现场试验结果一致.     

超声场中Al-1%Si合金水平连铸实验研究

研究了功率超声对水平连铸Al-1%(质量分数)Si合金凝固过程、合金组织和力学性能的影响,详细探讨了超声空化细化合金组织的机理.结果表明,在合金的凝固过程中施加功率超声可以提高形核率,使合金组织细化,从而提高其力学性能,并且随超声波功率的增加,铸坯的平均晶粒直径减小.     

Steam feed and effect of steam-thermal seal in thermolysis of tire shreds in a screw-type reactor

On the basis of experience in commercial operation, the effect of steam seal in tire-shred pyrolysis in a screw-type reactor with superheated steam has been considered and analytically substantiated; there, local steam feed produces the above effect at the total reduced pressure and keeps air from entering the reactor without sluices or valves used for hermetization of its loading and unloading. It has been shown that the increase in the production rate of pyrolysis due to the heating by steam amounts to 10–15% and is limited by the diffusion transfer in the reactor’s charge bed.     

碳系水性电热油墨在柔性电发热器件中的应用

制备了碳系水性电热油墨,通过丝网印制将其与金属条紧密相连制备柔性电发热器件。对柔性电发热器件性能的研究结果表明：在不同工作电压下,柔性电发热器件发热均匀稳定;通电电压越大,其饱和温度越高;面积越小,其饱和温度越高;折叠弯折近2000次后,其电阻变化率小于4%。因此该柔性电发热器件具有良好的电加热性能和优异的机械性能。     

Study on nanoparticle production process characteristics in transferred arc plasma system using heat and mass balance

The nanoparticle production process in a transferred arc plasma system was studied. The plasma temperature, particle heating time, and particle residence time in plasma were calculated using heat and mass balance with a lumped capacitance method. We analyzed the nanoparticle production characteristics based on different operating conditions by comparing the particle vaporization time with the particle residence time in the plasma. The limit size for particle vaporization was derived. With higher plasma power, the nanoparticle production rate increased and the energy consumption rate decreased. It was confirmed that the energy consumption rate reaches an optimal point according to the plasma power. Experiments to determine the nanoparticle production rate according to plasma power were also conducted and the experimental data were compared with numerical values. The results show that the error rate between the numerical values and experimental data was approximately ±18%. Therefore, the developed model which was studied could be useful for designing nanoparticle production process using a transferred arc plasma system because of its simple approach.     

Ambiguity of the mechanism of thermochemical destruction of thermoplastic heat-protecting materials

It has been established that, under nonstationary heating of thermoplastic heat-protecting materials in air flow, an ambiguous dependence of the material destruction rate on the temperature of its heating surface can occur.     

应用超滤技术改进Vc生产工艺

用超滤技术纯化Ｖｃ发酵液已在东北制药总厂（简称东药）年产万吨Ｖｃ生产线上应用,采用膜技术替代原工艺中的一次树脂交换和加热工序,具有速度快、节约能源、收率高等优点。自控清洗程序和国产洗膜剂的应用保证了超滤膜有较长的使用寿命。     

Numerical simulation and design optimisation of an integrally-heated tool for composite manufacturing

Tooling design is crucial for the production of cost-effective and durable composite products. As part of the current search for cost reduction, integrally-heated tooling is one of the technologies available for ‘out-of-autoclave’ processing of advanced thermoset polymer composites. Despite their advantages, integrally-heated tools can suffer from uneven distribution of temperature, variability in heat flow rate and inconsistency in heating/cooling time. This research, therefore, investigates a number of design variables such as shape and layout of heating channels in order to improve the thermal performance of an integrally-heated tool. Design of Experiments (DoE) has been carried out using Taguchi’s Orthogonal Array (OA) method to set several combinations of design parameters. Each of these design combinations has been evaluated through numerical simulation to investigate heating time and mould surface temperature variation. The simulation results suggest that the layout of the channels and their separation play a vital role in the thermal performance. Signal-to-Noise (S/N) ratio and analysis of variance (ANOVA) have been applied to the results obtained to identify the optimal design combination of the integrally-heated tool. Statistical analysis reveals that the heating performance of an integrally-heated tool can be significantly improved when the channels’ layout is parallel. The shape of the channels has negligible effect and the distance between the channels should be determined based on the production requirement.     

Effect of Heating Rates on the Formable Oxide Scale on a C-Steel Surface

Oxide scale formation on a C-steel surface has been investigated using linear heating rates ranging from 0.1℃/min to 10℃/min at high temperatures. The studies on the oxide scale formation at high temperature (650℃) at slower heating rate (0.1℃/min) shows that the kinetic regime is linear. X-ray diffraction measurements revealed that the scale constituents are significantly influenced by the heating rate. The adherence of the scale was improved by using slower heating rate (0.1℃/min-≤650℃),while above such degree the scale was susceptible to cracking and flaking out of the alloy surface. In fact, the development of oxide growth stresses can cause considerable scale cracking. As well, variation of the crystallite sizes under the aforementioned conditions might affect the scale stacking to the alloy surface. The secondary electron detector images of the oxide scale shows that the scale was imperfectly smooth and there were a number of voids and defects in the scale skin, especially at fast heating rate. This observation could be attributed to defects of the as-received alloy. In general, slower heating rate reduced the defects of the scale and improved its adherence.     

Peak capacity, peak-capacity production rate, and boiling point resolution for temperature-programmed GC with very high programming rates

Recent advances in column heating technology have made possible very fast linear temperature programming for high-speed gas chromatography. A fused-silica capillary column is contained in a tubular metal jacket, which is resistively heated by a precision power supply. With very rapid column heating, the rate of peak-capacity production is significantly enhanced, but the total peak capacity and the boiling-point resolution (minimum boiling-point difference required for the separation of two nonpolar compounds on a nonpolar column) are reduced relative to more conventional heating rates used with convection-oven instruments. As temperature-programming rates increase, elution temperatures also increase with the result that retention may become insignificant prior to elution. This results in inefficient utilization of the down-stream end of the column and causes a loss in the rate of peak-capacity production. The rate of peak-capacity production is increased by the use of shorter columns and higher carrier gas velocities. With high programming rates (100-600 degrees C/min), column lengths of 6-12 m and average linear carrier gas velocities in the 100-150 cm/s range are satisfactory. In this study, the rate of peak-capacity production, the total peak capacity, and the boiling point resolution are determined for C10-C28 n-alkanes using 6-18 m long columns, 50-200 cm/s average carrier gas velocities, and 60-600 degrees C/min programming rates. It was found that with a 6-meter-long, 0.25-mm i.d. column programmed at a rate of 600 degrees C/min, a maximum peak-capacity production rate of 6.1 peaks/s was obtained. A total peak capacity of about 75 peaks was produced in a 37-s long separation spanning a boiling-point range from n-C10 (174 degrees C) to n-C28 (432 degrees C).     

钽及钽合金在废酸回收设备中的应用

介绍了一种由钽及其合金管材加工而成的废酸浓缩回收设备的生产工艺,以及该设备中用于加热和冷却的钽制盘管换热器的生产工艺。并通过与传统废酸回收设备的经济效益对比,得出该钽制废酸回收设备在使用性能和效率上具有传统设备无法比拟的优势,具有显著的经济效益、环境效益和社会效益。推广应用前景广阔。     

Thermal quenching of thermoluminescence in natural quartz

The thermal quenching properties of the thermoluminescence (TL) from several natural quartz specimens were examined, at two different wavelengths, using the heating rate dependence of the TL signal. As the heating rate varies the TL peaks shift to different temperatures and become affected by thermal quenching to different extents. In this work the heating rate was varied over several orders of magnitude and, through deconvolution of the TL glow curve the behaviour of the main TL peaks was followed as a function of the temperature at which the peak appeared in the glow curve. Through an analysis of the glow peak areas as a function of glow peak temperature the decrease in the efficiency of TL production with increasing temperature could be monitored, at the different emission wavelengths. The analysis supports the contention that the quenching phenomenon is a result of a Mott-Seitz mechanism.