大型筒体锻造成形缺陷分析及预防

以大型简体锻造成形工艺为主要研究对象,将大型简体在锻造过程中产生的端面缺陷、内表面缺陷、外表面缺陷、形状缺陷产生原因进行了分析.将生产实际、锻造工艺理论和有限元数值模拟技术相结合,提出合理的预防措施及解决方法,为筒体锻件工艺优化及质量提高起到积极的作用.     

大规格钛阴极辊简体的制造方法及复合型大电流阴极辊

一种大规格钛阴极辊简体的制造方法及用此材料制作的复合型大电流阴极辊。其制造方法是：将钛板两端加热后模压使之成型出一定高度的凸缘；将钛板卷制成圆筒使模压成型的凸缘对接，并对接缝处焊接；将焊缝处加热后进行锻造，将锻造后的焊缝轧制，最后将钛筒整体热处理。     

不锈钢缓冲器筒体延迟焊接裂纹分析及预防措施

对不锈钢缓冲器简体延迟焊接裂纹进行了分析,并讲述了其预防工艺措施.     

等离子喷涂涂层锻造工艺参数优化研究

为了提高热喷涂涂层的致密度,降低涂层残余应力,提出了涂层喷涂锻造工艺.以涂层结合强度和孔隙率为目标函数,以锻造温度、锻造次数和打击能量为变量,采用正交设计法进行了涂层锻造工艺参数优化设计,确定了因素的主次关系,得到了最佳锻造工艺参数,并进行了锻造工艺试验验证.分别在30°和90°冲蚀角情况下,对未锻造试件和锻造试件进行冲蚀对比试验研究.结果表明,经喷涂锻造工艺制备的涂层耐冲蚀性能明显优于未锻造试件.     

压气机静子叶片锻造过程的三维刚粘塑性有限元模拟

利用三维刚粘塑性有限元法对某重型燃机压气机静子叶片的锻造过程进行了数值模拟分析,揭示了叶片锻造变形规律,并以实际锻造工艺试验对其进行了试验验证。锻造工艺试验与数值模拟结果吻合较好,从而验证了数值模拟结果的可靠性。该研究对压气机静子叶片锻造工艺的优化设计具有重要的指导意义。     

高合金钢冷轧工作辊锻造过程数值模拟

采用Deform-3D软件对一种新型高合金钢冷轧工作辊锻造以及锻前空冷过程进行数值模拟。首先,根据实际产品和液压机压头尺寸建立锻件和模具模型并进行了网格划分,对所采用的高合金钢进行热力学测试从而建立了材料模型。通过分析在空冷和锻造过程中锻件温度场和应力场分布,获得了锻件在空冷过程中温度变化规律,以及在锻造过程中锻造区域典型位置处的温度和应力分布特征。此外,参考模拟结果,并结合实际经验对这种新型冷轧工作辊进行锻造,实际锻造结果与模拟得到的最终结果十分接近,验证了采用有限元方法对轧辊锻造过程进行模拟是可行的。为冷轧工作辊的实际锻造生产提供理论指导。     

自由锻造液压机的技术现状及设计分析

阐述了自由锻造液压机的发展过程和我国锻造压机的技术现状,对自由锻造液压机的几种结构型式和传动方式进行了比较,说明了锻造油压机的技术特点。     

Cr12MoV钢大型锻件的锻造工艺

文章对Cr12MoV钢特大型锻件的锻造工艺进行了分析。通过实例锻件锻造生产,指出了现场锻造注意要点。     

径向锻造机的几种典型主机结构分析

简要介绍了径向锻造的起源和基本原理、实现径向锻造的工艺装备及径向锻造机的发展。根据径向锻造工艺的要求及锻造设备的结构特点,分析并选择了几种主要的径向锻造机主机的性能评价指标(锤头的同步度、锻造力、锻造频次、锻造精度、过载保护、运行费用和维护成本等)对其进行分析和评价。针对目前国内应用最广泛的4种不同主机结构的径向锻造机(GFM SX型、GFM SKK型、GFM RF型和SMS MEER SMX型)进行了重点分析,通过分析主机的基本结构原理和结构特点,综合评价了其对锻造工艺性能的影响。提出了径向锻造机国产化研制过程中存在的突出和共性的问题,并提出了一些解决的思路,为径向锻造机的国产化研制和应用提供借鉴。     

高锰钢铸件锻造工艺的研究

为成功开发质优价廉的锻造高锰钢芯轨组合辙叉,针对高锰钢铸件锻造工艺进行了研究.通过对不同高锰钢铸件试样的加热、金相组织观察及不同锻造比下的结果分析,确定了高锰钢的锻造温度范围、锻造比数值、铸件锻后直接水韧处理前锻件在空气中停留时间对质量的影响以及正确停留时间,制定了高锰钢铸件的锻造工艺.研究结果表明,高锰钢铸锭可以进行锻造,组合辙叉芯轨可以采用锻造高锰钢材质,从而可实现开发锻造高锰钢芯轨组合辙叉的预期目的.通过锻造消除铸造过程中存在的内部缺陷,提高使用性能,延长组合辙叉的使用寿命.     

几何结构参数对磨料水射流喷嘴磨损规律影响的模拟分析

建立了前混合磨料水射流喷嘴物理模型。基于FLUENT软件,采用颗粒轨道模型、Grant弹性恢复系数和E/CRC磨损模型对磨料水射流喷嘴内的磨损特性进行了数值模拟。结果表明:当喷嘴收缩角为20°以上时,喷嘴磨损呈现两个严重磨损区,分别在喷嘴圆柱段入口处前较短距离范围内和喷嘴圆柱段出口处前较短距离范围内;随着喷嘴收缩角的增大,磨料颗粒与喷嘴圆柱段壁面碰撞次数和速度增加,同时随着喷嘴长径比的增大,喷嘴圆柱段壁面磨损速率整体增加,严重磨损区范围扩大,结果均使喷嘴圆柱段的磨损加剧。以喷嘴壁面磨损速率的面积加权平均积分表征喷嘴整体的磨损程度。随着收缩角和长径比的增大,喷嘴壁面磨损速率的面积加权平均积分增大,喷嘴的磨损整体而言越严重。因此,从减小喷嘴磨损的角度而言,喷嘴的收缩角和长径比宜取小值。     

旋轮参数对铝合金分形旋压的影响规律

铝合金分形旋压是一个复杂的多因素耦合影响的塑性成形过程,研究其旋轮参数对成形过程的影响可为相关成形参数的确定和优化设计提供理论依据。基于建立的可靠的铝合金分形旋压三维有限元模型,文章研究揭示了旋轮分形角、旋轮圆角半径、旋轮轴向进给比等旋轮参数对成形过程中的切向拉应力、周向压应力以及成形凸缘的不均匀变形程度和最终壁厚偏差的影响规律。结果表明,增大旋轮分形角,可以消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小和成形精度降低;旋轮圆角半径的改变,对消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性影响并不明显,但增大旋轮圆角半径,可以使得成形凸缘的不均匀变形程度增大和成形精度升高;旋轮轴向进给比的改变,对消除旋轮前方的金属堆积和成形凸缘的成形精度的影响并不明显,但增大旋轮轴向进给比,可以降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小。     

大块涂层缺陷对碳钢腐蚀特性及阴极保护效果的影响

采用了环氧煤沥青作为涂层材料，研究了大块涂层缺陷对碳钢腐蚀特性及阴极保护效果的影响，测定了具有面积比例为4．91％大块涂层缺陷的Q235钢于3．5％NaCl水溶液中的交流阻抗谱．结果表明，随着浸泡时间的延长，在自然腐蚀电位下，存在剥离涂层缺陷时碳钢的腐蚀程度高于破损涂层缺陷时碳钢的腐蚀程度；在阴极极化条件下，具有剥离涂层缺陷的碳钢阴极保护效果随时间延长逐渐降低直至最后消失，而具有破损涂层缺陷时阴极保护效果随时间延长优于剥离涂层缺陷；电解质溶液向涂层内部的渗透以及涂层缺陷与钢基体间的缝隙腐蚀是导致具有大块涂层缺陷碳钢腐蚀的主要原因．     

Control of mechanized surfacing of stamping tools with modulation of conditions

The results of investigations of the effect of the regulated parameters of low-frequency modulation on the characteristics of deposited beads in reconditioning of the working surfaces of dies of stamping tools are presented. The effect of the frequency and duty ratio of the modulated conditions on the mechanical properties of the deposited layer and the structure of its metal is described. Recommendations are issued for the effective application of technology with the controlled modulated conditions in the reconditioning of the working edges of the dies of the stamping tools.     

Nonadditive phenomena during polyaniline synthesis in the presence of mixtures of rigid-chain and flexible-chain polymer sulfoacids and their effect on properties of obtained interpolymer complexes

The matrix polymerization of aniline in the presence of mixtures of rigid-chain and flexible-chain polymer sulfoacids was investigated in the work. The optical, electric, and spectroelectrochemical properties of the forming interpolymer complexes of polyaniline, as well as their morphology, were studied. The dominating influence of rigid-chain polyacid on the process of formation of the interpolymer complexes of polyaniline even in the case of application of the mixture with the prevailing content of the flexible-chain polyacid was detected. The nonadditive dependence character of the viscosity of the mixtures of polyacid solutions, the duration of the induction period of aniline polymerization, and the optical absorbance and conductivity of the obtained complexes of polyaniline relative to polyacid ratios in the mixture was shown. The presence of the intermolecular interaction in the mixtures of polymer sulfoacids was shown via viscometry method, which may be the reason for the nonadditivity of the observed phenomena.     

基于PDM集成框架的BOM表自动生成及其数据一致性研究

PDM系统中企业各部门实现信息共享的形式是生成不同部门所需要的BOM表，BOM表信息的准确性和一致性对产品的设计过程有重要的影响。BOM表信息来自设计部门绘制的工程图纸的明细表和标题栏，本文提出了保持BOM表、标题栏表、明细表三表数据一致性的算法。实现了PDM集成框架下产品结构树、BOM表的自动生成，保证了产品BOM表信息的准确性和一致性，实现了产品数据在企业内的共享。     

Defects caused by corrosion cracking in circumferential welded joints of transmission gas pipelines in two climatic regions of Russia

It is shown that a very large number of anomalies of welded joints are detrimental for the safe service of a system of transmission gas pipelines not only because of the possibility of failure of the welded joint but also because of the formation of the additional factor of nucleation and propagation of stress corrosion cracking defects in the zone of interaction of longitudinal and circumferential welded joints.     

Modelling of processes of thermochemical treatment of metals: traditions of Russian scientific school

Abstract

The paper is devoted to 100th anniversary of the outstanding Russian scientist professor Yuriy Mikhailovich Lakhtin – the founder of the world-famous scientific school of surface strengthening of metals and alloys. Lakhtin's scientific school is recognised for its contribution into research of processes of thermochemical treatment of metals and especially of nitriding. Today at the Department of Metal Science and Heat Treatment of MADI his followers continue the traditions of Lakhtin's scientific school. The development of technologies of surface engineering is based on complex modelling of physical processes realised by thermochemical treatment of metals. Thermodynamic models describe the interaction between metals and components of saturating atmosphere and predict phase composition of diffusion layer. Diffusion models of kinetics of saturation of metals allow us to calculate the rate of growth of diffusion layer and regulation of its depth and structure. Structural models determine quantitative dependence between parameters of structure (grain size, dispersed particles, etc.) and mechanical properties. These models allow us to estimate the level of strengthening by control of structural specifics of strengthened layer. On the basis of this complex of models, new efficient technologies of surface strengthening are developed.     

Special features of the formation of the microstructure and chemical heterogeneity in welded joints in alloys of the Al–Zn–Mg–Cu system alloyed with scandium

Special features of the formation of the microstructure and the development of chemical heterogeneity in the weld metal and heat-affected zone (HAZ) in arc welding of a complex alloyed alloy of the Al–Zn–Mg–Cu system are discussed. It is shown that the effect of welding heating results in melting of the phase components of the alloy in the HAZ with the formation of structures of the eutectic origin in the form of long interlayers at the boundaries of recrystallized grains, causing brittleness of the metal. Alloying the alloy with scandium reduces the intensity of the processes of recrystallization and the extent of liquation at the grain boundaries and also localizes the melting of the grains without the formation of thick eutectic interlayers.