钢中夹杂物与韧断机理

用平板拉伸试样直接观察夹杂物在裂纹成核和扩展中的行为得出:夹杂物开裂受应变控制:夹杂物开裂方式与加载方向有关;微裂纹在夹杂物上成核后主要按基体切变方式扩展;在夹杂物偏聚区微裂纹的扩展可按碰撞方式进行,从而加速裂纹的扩展,故在冶炼上需采取措施,以避免夹杂物的集聚。     

MnS+TiN夹杂物对超高强度钢韧性的影响

超高强度钢中常见的两类夹杂物为MnS和TiN,它们共同对韧性的影响迄今尚未系统研究过。本文以D_6AC钢为基体,分别改变硫和氮的含量,使钢中含有8种不同含量的MnS+TiN夹杂物。通过板状试样拉伸实验,观察裂纹在夹杂物上形核和扩展的准动态过程,并测定了试样的常规机械性能和断型韧性。试验结果表明,夹杂物总体积分数fv和平均间距dT是影响K_1c和a_K值的两个重要参数。结果还表明,随着夹杂物尺寸的增加,裂纹临界形核应变降低。在相同尺寸情况下,裂纹在TiN上形核的临界应变比在MnS上形核小,因而MnS对韧性的影响低于TiN。     

夹杂物问题应力场的数值计算

等效夹杂物方法是细观力学中的一种重要方法，文中编制的数值计算程序能在考虑多个夹杂物相互响应的情况下计算材料应力、应变场，并实现了计算结果的三维显示．计算结果与文献中的计算结果非常吻合．本文编制的数值计算程序不仅可以用于研究复合材料的损伤演化及失效，而且利用特殊构型的椭球空洞来模拟裂纹，可以计算裂纹群的应力、应变场。     

铁路起重机支腿液压缸托架致裂分析

本文根据１６０吨铁路起重机支腿液压托架上裂纹的金相检验情况，分析得出裂纹产生的根本原因，裂纹并非热处理不当而引起的淬火裂纹，而是热处理以前就已存在于锻件毛坯中的，由钢中非金属夹杂物引起的微小锻造裂纹，因受以热处理应力作用而扩展。     

1Cr18Ni9Ti不锈钢在硫化氢水溶液中的台阶状应力腐蚀破裂

用恒变形Ｕ形试件应力腐蚀试验，电化学极化和ＡＥＳ分析法研究了１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢在室温Ｈ２Ｓ水溶液和９０℃的Ｈ２Ｓ＋０．６ｍｏｌ／ＬＮａＣｌ水溶液中的应力腐蚀破裂，两种条件下都发现了台阶状的应力腐蚀裂纹，９０℃时的破裂由［Ｃｌ］导致的阳极溶解机理控制，沿夹杂物／基体界面及轧制方向晶界的择优溶解导致台阶状裂纹。在室温无ＮａＣｌ的Ｈ２Ｓ溶液中，破裂机理为氢致开裂，塑性变形造成的局部硬度增高     

铝合金疲劳裂纹扩展过程中夹杂物影响的量化分析

本研究测量了Al 7075—T651铝合金的疲劳裂纹扩展率和中间△K疲劳载荷区间的疲劳条纹间距,对材料微观结构在疲劳裂纹扩展中的作用进行了量化分析,建立了剪切断裂机制和夹杂物断裂—韧窝形成机制引起裂纹扩展的实验方程。研究还发现了K_(max,o)和K'c两个转折点,低于K_(max,o),裂纹仅由剪切断裂机制引起;高于K'c,裂纹由夹杂物断裂—韧窝形成机制主导,在K_(max,o)和K'c之间,疲劳裂纹扩展由上述两者共同组成。     

球形颗粒增强铝基复合材料的细观失效分析

针对ZrO2球形颗粒增强2124铝基复合材料完成了静拉伸断裂实验及细观失效分析,主要研究了颗粒夹杂物对铝基复合材料的细观结构演化及失效的影响。结果表明：颗粒与基体材料的脱粘以及颗粒的开裂是材料的主要细观损伤形式,开裂颗粒之间的基体材料中容易形成连接颗粒理解缝的微裂纹,并对材料的失效有重要的影响,球体形颗粒是最为合理的增强体形状。     

铍青铜挤压棒材端头开裂的原因分析

针对铍青铜棒材挤压过程中产生的端头环状开裂问题进行了分析研究,对开裂位置进行定点取样分析化学成分和金相组织,并采用扫描电子显微镜和电子探针对开裂断口和微观组织进行分析检测.分析结果表明,铍元素偏聚、夹杂物偏多和空洞的聚集是产生开裂的根本原因.     

20MnSi钢螺纹钢筋裂纹产生原因研究

研究了２０ＭｎＳｉ螺纹钢冷弯裂纹处的金相组织，夹杂物，机械性能及化学成分。结果表明，魏氏组织及夹杂物偏多是造成２０ＭｎＳｉ２钢螺纹钢筋冷弯裂纹的主要原因，提出了预防措施，为实际生产提供了依据。     

裂纹夹杂相互干涉问题

本文研究裂纹夹杂相互干涉的弹性力学的平面问题。一对位错和一对集中力的格林函数被分别用以形成裂纹和夹杂。所得积分方程适合于任意相对方位和尺寸的一个裂纹和一个夹杂。文中描述了裂纹尖端附近应力场的奇异性。对夹杂尖端附近应力场的奇异性给予了特别的注意,并为夹杂尖端的应力强度因子作了定义。对各种不同的裂纹夹杂几何情况和不同的夹杂刚度作了数值计算。根据这些数值结果--裂纹尖端和夹杂尖端的应力强度因子,分析、讨论了裂纹夹杂的各种几何参数以及夹杂-母体材料刚度比对裂纹夹杂相互干涉效应的影响。     

模糊信息表决策规则获取与属性约简方法

将粗糙集方法用于模糊信息表上的规则获取和属性约简, 在包含度概念的基础上, 定义了齐次包含度.对两类模糊信息值的信息表, 条件属性是离散值，而决策属性是模糊的模糊决策信息表和条件属性与决策属性均为模糊的模糊信息表, 采用齐次包含度研究了条件属性在决策属性中的包含关系, 得到了包含度意义下模糊决策信息表的属性约简判定定理和决策规则获取方法. 给出了模糊条件属性的所有可能组合, 研究了模糊组合属性在模糊决策属性中的包含关系, 提出了最大属性协调集的概念，建立了在最大协调属性集下的模糊信息表属性约简和决策规则获取的算法步骤, 并通过算例演示了模糊决策规则获取和属性约简的过程, 从而为模糊信息表决策规则获取与属性约简提供了一类算法.     

Elastic Properties of Particulate Composites with Imperfect Interface

An effective analytical approach is developed for the problem of particulate composites containing spherical inclusion with imperfect iraerface between the matrix and spherical inclusions. In this paper, a general interface model for a variety of interracial defects has been presented, in which both displacement discontinuity across the interface and the elastic moduli varing with radius outside of the inclusion are considered. The imperfect interface conditions are appropriate in the case of thin coatings on the inclusion. Furthermore, in the ease of thin elastic interphase , the displacement field and the stress field in the inclusion and matrix are exactly solved for the boundary problem of hydrostatic compression of an infinite spherical symmetrical body by Frobenius series, and the erpression of the normal interface parameter, Dr, is derived. In addition, it has been proved that two previous results derived in some literatures by considering the interface to be a thin iruetptmse with displacement jump or with some variance in its moduli can be reverted from the present formula, respectively. Numerical results are given to demonstrate the significance of the general imperfect interface effects.     

双材料中多个热膨胀夹杂引起的弹性场

目的确定在双材料中由具有均匀本征应变的任意多个夹杂引起的热弹性场．方法利用Papkovitch-Neuber调和势函数得到无限大体中热膨胀夹杂产生的弹性场，通过应变核等基本解和镜像法得到双材料中多夹杂引起的热弹性场．结果阐述两相材料界面的效应、夹杂与界面的距离、弹性模量以及夹杂形状尺寸等参数对弹性场的影响．结论给出的应力公式和分布曲线，可扩展以建立双材料中热应力问题的断裂破坏准则，能有效地用来确定在双材料中由具有均匀本征应变的任意多个夹杂引起的热弹性场．     

Numerical simulation on inclusion transport in continuous casting mold

Turbulent flow, the transpor＇t of inclusions and bubbles, and inclusion removal by fluid flow, transport and by bubble flotation in the strand of the continuous slab caster are investigated using computational models, and validated through comparison with plant measurements of inclusions. Steady 3-D flow of steel in the liquid pool in the mold and upper strand is simulated with a finitedifference computational model using the standard k-εturbulence rondel. Trajectories of inclusions and bubhles tire calculated by integrating each local velocity, considering its drag and buoyancy forces, A ＂random walk＂ model is used to incorporate the effect of turbulent fluctuations on the particle motion. The attachment probability of inclusions on a bubble surface is investigated based on fundamental fluid flow simulations, incorporating the turbulent inclusion trajectory and sliding time of each individual inclusion along the bubble surface as a function of particle and bubble size. The chunge in inclusion distribution due to removal by bubble transport in the mold is calculated based on the computed attachment probability of inclusions on each bubble and the computed path length of the bubbles. The results indicate that 6%-10% inclusions are removed by fluid flow transport. 10% by bubble flotation, and 4% by entrapment to the submerged entry nozzle （SEN） walls. Smaller bubbles and larger inclusions have larger attachment probabilities. Smaller bubbles are more efficient for inclusion removal by bubble flotation, so Inng as they are not entrapped in the solidifying shell A larger gas flow rate favors inclusion removal by bubble flotation. The optimum bubble size should be 2-4mm.     

环糊精接枝纺织纤维的研究进展

对纺织领域常用的几种环糊精接枝纤维的改性方法及原理进行了综述.对纤维素纤维的改性可采用环氧氯丙烷活化纤维素法、一氯均三嗪改性环糊精、醛类交联剂和多元酸交联剂固载法等,根据不同的需求来选择相应的接枝方法;对于壳聚糖纤维的接枝改性可通过将环糊精改性制成环糊精醛来进行;对于聚酰胺纤维的接枝改性可使用含有磺酸基的β-环糊精衍生物来进行;对于羊毛、真丝纤维则利用其它的环糊精衍生物来进行改性处理.不同纤维,其化学改性方法不同;同一种纤维根据使用要求可采用不同的化学方法进行改性.整理后的纤维既能体现本身的优良性能,又可发挥环糊精包合性能,这为开发功能性纺织材料提供了参考依据.     

SEM In-situ Observation at Tensile Loading on Surface Inclusion in PM Rene95 Superalloy

The observation on crack initiation and propagation of surface inclusion Al2O3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion / matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion / matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface in-elusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can't be ignored.     

含刚性圆柱夹杂压电介质的动力反平面特性

利用复变函数和波函数展开法对稳态SH波在含刚性可移动圆柱夹杂的无限线弹性压电介质中的散射与动应力集中问题进行研究．获得压电介质中刚性圆柱夹杂周边动应力的表达式，并对具有不同压电特征参数和不同波数情况下的夹杂边界动应力集中系数进行了数值计算．计算结果表明，边界动应力集中对外加电场压电参数具有线性依赖关系，对含刚性可移动圆柱夹杂的压电介质进行低频和大压电特征参数情况下的动力分析是非常重要的。     

Acoustic band gaps in two-dimensional square arrays of semi-hollow circular cylinders

Concave surfaces focus sound while convex surfaces disperse sound. It is therefore interesting to know if it is possible to make use of these two opposite characteristics to enhance the band gap performance of periodic arrays of solid cylinders in air. In this paper, the band gap characteristics of a 2-D square array of semi-hollow circular cylinders embedded in air are investigated, both experimentally and theoretically. In comparison with the types of inclusion studied by previous researchers, a semi-hollow circular cylinder is unique in the sense that it has concave inner surfaces and convex outer surfaces. The finite difference time domain (FDTD) method is employed to study the propagation behavior of sound across the new phononic crystal of finite extent, and the influences of sample size and inclusion orientation on band gap characteristics are quantified in order to obtain the maximum band gap. For reference, the band gap behaviors of solid circular cylinder/air and hollow circular cylinder/air systems are considered and compared with those of semi-hollow circular cylinder/air systems. In addition to semi-hollow circular cylinders, other inclusion topologies such as semi-hollow triangular and square cylinders are also investigated. To validate the theoretical predictions, experimental measurements on square arrays of hollow Al cylinders in air and semi-hollow Al cylinders in air are carried out. The results demonstrate that the semi-hollow circular cylinder/air system has the best overall band gap performance.     

夹杂对粉末冶金CT试样断裂性能影响的计算研究

采用GURSON本构方程对含夹杂粉末冶金材料紧凑拉伸试样进行了有限元分析,模拟了裂尖与夹杂的相互作用对基体的损伤及裂纹扩展性能的影响.圆形夹杂对基体材料的损伤及裂纹扩展性能是最保守的形状,对于椭圆形夹杂,硬夹杂在椭圆横向受力较为安全,而软夹杂则相反,在椭圆纵向受力对基体的损伤更小.     

Influence of Inclusion Shape on Thermoelasto-Plastic Optimun Design of Ceramic Metal Functionally Graded Materials

A nonlinear finite element method is applied to observe how inclusion shape influence the thermal response of a ceramic-metal functionally graded material (FGM). The elastic and plastic behaviors of the layers which are two-phase isotropic composites consisting of randomly oriented elastic spheroidal inclusions and a ductile matrix are predicted by a mean field method. The prediction results show that inclusion shape has remarkable influence on the overall behavior of the composite. The consequences of the thermal response analysis of the FGM are that the response is dependent on inclusion shape and its composition profile cooperatively and that the plastic behavior of each layer should be taken into account in optimum design of a ceramic-metal FGM.