CSBA在水雾化钢中的应用

水雾化法制粉钢液治炼的氧含量控制是影响雾化效果的重要因素,实践证明,采用CSBA(Ca、Si、Ba、Al合金)新型脱氧合金用于水雾化钢液终脱氧,具有明显降低钢中氧含量、提高雾化效率,改变夹杂物形态作用,可推荐为水雾化钢液终脱氧工艺中首选脱氧合金。     

采用海绵铁制备部分预合金铁粉试验研究

采用海绵铁为原料制备部分预合金铁粉并对其生产工艺进行了研究。试验表明,与传统的制备方法相比,这种方法对二次还原时的工艺参数要求比较严格,但缩短了生产工艺流程,降低了生产成本,因此,值得进一步研究和中试。     

铁粉温压工艺致密化过程研究

在Instron材料试验机上对纯铁粉和添加了不同润滑剂的铁粉致密化过程进行了研究;用扫描电镜观察了铁粉的形貌,用X射线衍射方法测试了压坯中铁粉晶粒(110)晶面衍射峰的半高宽,并测定了粉末的氧含量和压坯的显微硬度.结果表明:在不同的压制压力下,纯铁粉在室温压制时的压坯密度均高于130℃时压制的,其室温时的(110)面衍射峰半高宽也高于同样压力下130℃时压制的;在室温压制时,添加硬脂酸锌的铁粉在不同压力下的压坯密度均高于添加WSA的铁粉;而添加了硬脂酸锌和WSA的铁粉在130℃压制时,其压坯密度高于同样压力下室温压制时的;此外,纯铁粉在温压时,其粉末颗粒的加工硬化程度增加;而添加了润滑剂的铁粉在温压时塑性变形能力提高,减缓了压坯加工硬化的趋势.     

润滑剂含量对雾化铁粉温压行为的影响

采用水雾化铁粉,分别加入不同含量的润滑剂,以常温压制与温压两种压制方式成形,温压温度为130℃;测量了压坯、烧结坯的密度和弹性后效,并进行了对比与分析.结果表明:润滑剂的适量加入可以提高粉末的流动性以及减小其与模壁间的摩擦力,从而得到更高的压坯密度与烧结密度,加入量最佳值为0.4%(质量分数)左右;同时,温压可提高粉末的生坯密度、烧结密度,并且可以降低弹性后效和脱模力;常温压制的压坯密度和烧结坯密度最高值分别为6.89和7.10 g·cm-3,而温压的则提高至7.06和7.26 g·cm-3.     

高颈法兰盘轧制成型的试验研究

介绍了一种高颈法兰盘的轧制成型情况。通过几种法兰毛坯的试验轧制 ,得出了该种法兰盘虽难以轧制成型 ,但对铸造成型与轧制成型相结合以提高法兰盘质量提供了有力的依据。该方法可以做为高颈法兰盘制造新工艺的一种参考。     

金属粉末轧制工艺及其数值模拟

金属粉末轧制工艺能够生产一般工艺难于或无法生产且成分精确、质地均匀、性能优良的带材,是一种制取高性能以及特殊用途材料的很有前途的粉末冶金成形工艺。粉末轧制工艺中的力学行为较难通过传统的数学模型综合准确地研究。基于有限元方法的数值模拟为研究粉末轧制过程中的力学特性提供了一种灵活高效的途径。在有限元方法中可以同时引入复杂的几何模型、材料本构模型、摩擦模型等多种信息,能够对轧制过程的相对密度、材料流动及力能参数进行预测,可以更准确地综合研究粉末轧制的力学特性。从而有效地为轧制工艺的制定、润滑方案及设备的优化设计提供帮助。     

金属粉末轧制工艺及装置研究

概述金属粉末轧制工艺,分析金属粉末的性能、轧制速度、辊径、辊缝、给料方式等工艺参数对粉末轧制性能的影响。设计一台金属粉末专用轧制试验装置,采用有限元软件对轧制装置进行模态分析和静力分析,计算结果表明,轧制装置工作时的变形趋势小,对轧件精度影响小,装置机械结构满足材料的强度条件和刚度条件要求。     

A theoretical study on the application of asymmetric rolling for the estimation of friction

In this work, a method for the estimation of friction coefficient is proposed based on the asymmetric rolling operation. Asymmetry is produced by operating the lower and upper rolls at different speeds. A slab method based computer code is developed for estimating the curvature of the rolled sheet under asymmetric rolling conditions. Strain-hardening behavior of the material has been incorporated and Wanheim and Bay's friction model is employed. The developed code is used for solving the inverse problem of estimating the coefficient of friction by measuring the curvature of the rolled sheet under known operating conditions. The simulations show a good potential of the method.     

铸铁阀门的粉末涂层工艺探讨

探讨了水系统用铸铁阀门和铸铁管道配件的功能性防护涂层的现状、材料和工艺。     

Effect of friction between powder and a mandrel on densification of iron powder during cold isostatic pressing

The effects of friction between the powder and the mandrel on densification behavior of metal powder were investigated under cold isostatic pressing. The friction coefficients between the powder and the mandrels with different surface roughness were determined from the relationship between the compaction pressure and the ejection pressure of the mandrel from powder compacts. The elastoplastic constitutive equations based on the yield function of Shima and Oyane were implemented into a finite element program (ABAQUS) to simulate compaction responses of metal powders during cold isostatic pressing. Finite element results were compared with experimental data for pure iron powder under cold isostatic pressing.     

Analytical and experimental study on asymmetrical sheet rolling

An analytical model assuming constant shear friction between the rolls and sheet is proposed to explore the characteristics of asymmetrical cold and hot sheet rolling. In the hot sheet rolling process, the surface friction stress is assumed to be equal to the yield shear strength (i.e. τ = k). As the friction factor m is less than 1, the simulation for the cold rolling process can be conducted. To verify the validity of the proposed analytical model, a series of experiments on asymmetrical cold sheet rolling of aluminium are carried out. The total rolling force and the forward slip are measured. The proposed model is also used to estimate friction factor (m) with the measured forward slip. With the estimated friction factors, the analytical rolling forces are calculated to compare with experimental data. Reasonable agreement is found. By this proposed analytical model, it is noted that a large amount of calculation time and computer expense are saved, and the characteristics of asymmetrical cold and hot sheet rolling are obtained easily and rapidly.     

Powder size measurement by acoustic emission

Acoustic emission was used to measure particle size properties of steel, cast iron, and alumina powders. Many powder samples with different weight and size distribution were prepared by sieving and their size distribution was measured by means of optical techniques. Acoustic emission measurements were carried out by dropping the powder on a metal plate to which an acoustic emission transducer was fixed, and results were expressed in terms of number of counts of four channels for data acquisition. The measurement set-up and procedure were original and never investigated before. Very good results were obtained for steel and cast iron samples, as measurement curves showed a clear linear trend as a function of the particle mean diameter and were vertically shifted in dependence of the sample weight. Alumina powders showed similar trends only for large particles and high weight differences.     

以MSC.Marc为基的极片粉末轧制有限元模拟

粉末轧制工艺中的力学行为较难通过传统的数学模型综合准确地研究。但是基于有限元方法的数值模拟为研究粉末轧制过程中的力学特性提供了一种灵活高效的途径。在有限元方法中可以同时引入复杂的几何模型、材料本构模型和摩擦模型等多种信息,能够对轧制过程的材料流动及力能参数进行预测,可以更准确地综合研究粉末轧制的力学特性。     

粉环压制致密规律研究

本文运用虎克定律与弹塑性理论,研究了粉环三种压制方式的致密规律,导出了这三种压制条件下压坯密度与压制压力的理论公式。通过高能电池用MnO2粉环压制实验,证明理论计算与实验结果是一致。     

Zinc oxythiomolybdate (ZnMoO2S2) powder as a solid lubricant for high-temperature rolling contact applications

Conventional liquid lubricants being used in today's gas turbine engines will not be able to operate effectively in the hostile bearing environments expected in future turbine engines. The expected high operating temperatures (500–800°C) mandate new and innovative lubrication schemes to achieve success. Recent studies have demonstrated that a new class of solid lubricants, the complex chalcogenides or metal ocythiomolybdates, have good potential for high temperature lubrication. This paper describes the friction, wear and rolling contact endurance of three high-temperature bearing materials using a zinc oxythiomolybdate (ZnMoO₂S₂) powder lubricant. Rolling contact tests were conducted using VIM-VAR M50, micromelt T15 tool steels and silicon nitride (Si₃N₄) at temperatures ranging from 23°C to 649°C, using a modified ball-on-rod type rolling-contact fatigue tester. Significant improvements in friction, endurance and wear were observed at all test temperatures, and with all three materials evaluated, when ZnMoO₂S₂ was used as a lubricant. Overall, silicon nitride exhibited the best frictional and antiwear performance. The lubricant powder exhibited the best tribological performance with T15 and M50 specimens between 177°C and 316°C. Energy Dispersive X-Ray Analysis (EDAX) of wear tracks showed the presence of iron (Fe) on the Si₃N₄ specimens as well as the presence of zinc (Zn) on both the T15 and the M50 specimens.     

Investigation of interfacial behaviors between the strip and roll in hot strip rolling by finite element method

A finite element (FE)-based approach is presented for the precision analysis of the interfacial thermo-mechanical behavior of the roll and strip in the entire tandem mill during hot strip rolling. The validity of the proposed model is examined through the comparison with measurements. Then, the effect of various process parameters on the detailed aspects of interfacial thermo-mechanical behavior of the roll and strip is investigated via a series of process simulations.