不同压缩比2205双相不锈钢轧制复合板组织及性能对比研究

研究了不同压缩比2205双相不锈钢轧制复合板界面和复层的组织和性能。结果表明,压缩比为4和6的复合板复层均由奥氏体和铁素体组成,奥氏体和铁素体相界呈锯齿状;基层和复层界面处碳钢侧为单一铁素体,不锈钢侧可见一条不连续黑色条带;相比压缩比为4的复合板,压缩比为6的复合板复层铁素体含量更高,奥氏体γ相尺寸更小更长,耐腐蚀性更好,但强度无明显差异;基层和复层界面更平整,结合力更低。     

铝-钢爆炸复合板的研究

进行了三种质量比的铝－钢爆炸复合板试验,所有复合板界面焊合良好,焊合率〉９５％,结合强度〉６０ＭＰａ,而且基,复层材料对爆炸冲击波响应的硬化程度不明显,但结合界面存在铁,铝金属间化合物,故复合时应仔细选择爆炸参数,昼减少其生成量。     

冷轧成形钛/钢层状复合板界面结合强度的影响因素EI北大核心CSCD

采用冷轧复合法制备钛/钢层状复合板,研究轧制压下率、轧制道次、表面粗糙度、原材料状态和轧制速率对钛/钢层状复合板界面结合强度的影响。结果表明:界面作用力和轧制力对界面的作用时间是影响钛/钢层状复合板界面结合强度的主要因素。轧制压下率、表面粗糙度和原材料状态通过影响界面作用力来影响钛/钢层状复合板的界面结合强度;轧制速率通过影响轧制力对界面的作用时间来影响钛/钢层状复合板的界面结合强度;钛/钢层状复合板的冷轧复合效果与轧制道次无关,只有单道次轧制压下率超过临界轧制压下率时,才能实现冷轧复合。     

冷轧成形钛/钢层状复合板界面结合强度的影响因素

采用冷轧复合法制备钛/钢层状复合板,研究轧制压下率、轧制道次、表面粗糙度、原材料状态和轧制速率对钛/钢层状复合板界面结合强度的影响。结果表明:界面作用力和轧制力对界面的作用时间是影响钛/钢层状复合板界面结合强度的主要因素。轧制压下率、表面粗糙度和原材料状态通过影响界面作用力来影响钛/钢层状复合板的界面结合强度;轧制速率通过影响轧制力对界面的作用时间来影响钛/钢层状复合板的界面结合强度;钛/钢层状复合板的冷轧复合效果与轧制道次无关,只有单道次轧制压下率超过临界轧制压下率时,才能实现冷轧复合。     

钛钢复合板双金属的流变行为及轧制制备

基于采用单轴压缩实验得到的钛钢双金属流动变形规律,对钛钢复合板进行了不同工艺的轧制及热处理,并系统分析了不同工艺下钛钢复合板的微观组织、界面特征以及力学性能。结果表明,随着钛钢厚度比的增大、变形温度的升高,双金属流动性差异增大;根据应力-应变曲线,采用Levenberg-Marquardt法建立了变形抗力预测模型,预测应力值与实测应力值拟合优度为0. 961;钛钢复合板在800～900℃进行大压下量轧制得到的板材力学性能最优。在750℃下进行热处理时,界面处TiC层较厚且厚度不均匀;在850℃下进行热处理时,界面处TiC层平直且厚度均匀。在950℃下进行热处理后,界面化合物以TiFe为主,TiC分布于Ti Fe两侧且呈分层分布。同时,铁素体基体出现TiC沿晶界、晶内析出现象,增大冷却速度可对析出物的尺寸进行控制。     

平头压头下基体对压痕规律的影响研究

本文通过对软薄膜/硬基体两相材料体系的平头压痕弹塑性模拟.重点研究了平压头压入过程中,不同屈服强度比(软薄膜屈服强度与硬基体屈服强度之比)以及不同压头尺寸下硬基体对压痕规律的影响.研究发现硬基体对压痕规律的影响与屈服强度比近似满足线性关系,且这种线性关系不随压头尺寸的改变而改变,相同压头半径下,屈服强度比越大,影响就越明显;相同屈服强度比下,压头半径越大,影响就越小.研究还发现压头压入过程中,材料的堆积对压入深度没有影响.     

层状复合材料界面结合强度非传统评价方法

简要总结了层状复合材料界面结合强度的非传统评价方法。非传统界面结合强度评价方法包括:波振法(激光层裂法、应力波法、超声波法、电磁波法)、划痕法(激光划痕法)、辅助分析法(X射线衍射法、有限元法、解析法)和其他方法(电阻法)。波振法是将载荷以冲击波的形式施加在界面位置处,实现复层和基体分离。划痕法是将高能激光作用于复层,分离界面,实现界面结合强度的测量。电阻法通过建立界面电阻和界面强度之间的关系,评价界面结合强度。与传统界面评价方法对比,非传统评价方法有特殊优点:对材料的破坏程度小,有效抑制材料的弹塑性变形,测得界面强度接近界面本征强度。但非传统法也仍存在一些亟待解决的问题,随着新材料的不断出现,需要不断改进现有测试方法,使界面结合强度评价方法向着简单易行、无损、自动化的方向发展。     

热处理温度对爆炸焊接T2+Q345R复合板组织和性能的影响

研究了热处理对爆炸焊接T2+Q345R复合板组织和性能的影响.结果表明,热处理温度对T2+Q345R复合板的剪切、拉脱、伸长率等影响不明显,650℃以下,复层晶粒度增长缓慢,界面处异种金相组织厚度较爆炸态变化不大;650℃以上,随温度升高,复层晶粒度急剧增长,界面处异种金相组织厚度较爆炸态快速增加.     

短纤维增强金属基复合材料的多重损伤分析

用细观计算力学的方法分析了短纤维增强金属基复合材料(MMC)多重损伤的相互作用及对拉伸强度的影响。采用唯象的内聚力模型模拟界面的脱粘;G-T模型描述延性基体的损伤。在胞元模型的基础上研究了界面强度、纤维长径比等细观参数对材料损伤模式及强韧性的影响。研究表明,界面较弱时,损伤以界面脱粘为主,界面的强度决定了材料强度;当界面较强时,晶须将发生断裂,材料的最终强度由晶须的强度决定。不同界面强度条件下基体中损伤的分布不同。      

复合板基层厚度对激光焊接头腐蚀性能的影响

目的通过探索基层金属厚度对复合板激光穿透焊接的影响规律,分析其影响度与焊接速度、激光功率的差别,为双金属复合材料激光穿透焊接提供更多的技术支撑。方法以焊接速度、激光功率和基层金属厚度为变量,设计了三因素三水平的正交实验,对X65/DSS2205层状双金属复合材料进行激光穿透焊接实验,对不同焊接条件下接头的显微组织进行观察分析,采用EDS面扫方法对焊缝复层区进行成分扫描,测量接头复层侧动电位极化曲线,并比较了基层金属厚度的影响度较焊接速度与激光功率的大小。结果双金属复合板激光穿透焊接接头显微组织在厚度方向存在明显的分层;基层金属厚度为1.2 mm时,复层贵金属元素保留量最大;随着基层金属厚度的减小,接头综合耐腐蚀性能提高;基层金属厚度对接头耐腐蚀性能的影响小于焊接速度和激光功率2个变量;焊接速度为2.5 m/min,激光功率为3500 W,基层金属厚度为0.8 mm时,接头耐腐蚀性能最优。结论基层金属厚度对于复合板激光穿透焊接接头的焊缝复层元素含量、以及接头复层一侧耐腐蚀性能都有较为明显的影响,但相比于焊接速度与激光功率,其影响度相对较小,因此在进行复合板激光穿透焊接时,在选定基层金属厚度后,仍要对焊接速度和激光功率进行优化工艺设计。     

Bending Response of Foldcore Composite Sandwich Beams

In order to solve bending behavior difference of corrugated structure in L andWorientation, bending response for composite sandwich beams with foldcores of three different wall thicknesses were experimentally and numerically investigated. Effect of the cell walls thickness on the strength and failure behavior of the composite sandwich beams with L and W orientations was also examined. The deformation mode was obtained by the numerical method; a constitutive law of laminated material has been incorporated into a finite element (FE) analysis program. Numerical calculations give accurate prediction to the bending response of foldcore composite sandwich beams comparing with experiments. Structural flexural stiffness, strength and failure mechanism at a given topological geometry depended on the nature of core itself: the bending stiffness and strength of the sandwich beam increased with the core wall thickness (relative density). Also, bending isotropy was shown in this study for foldcore composite sandwich beams with selected core geometry.     

铜／铝冷轧复合板剥离性能及界面摩擦分析

采用同步轧制方法制备铜／铝复合板,研究了轧制变形量对于铜／铝复合板结合强度和剥离表面形貌的影响,分析了轧制复合界面摩擦机理。研究结果表明,复合板结合强度、剥离表面粘铝、铜基体表面裂纹数都随着轧制变形量的增大而增大。变形量为50％时,结合强度为2N／mm,变形量为60％时,结合强度为7N／mm,变形量为70％时,结合强度为14N／mm。轧制过程中,新鲜金属从结合面裂纹中挤压出来,受界面摩擦力剪切作用,两新鲜金属搓合在一起形成良好结合。     

泡沫铝夹芯板抗冲击性能分析

试验设计了3块钢板夹泡沫铝夹芯板,厚度分别为50 mm、70 mm和100 mm。对每种厚度夹芯板进行七组不同落锤高度的冲击试验,测得了上、下面板变形值,记录了夹芯板的破坏情况。应用数值模拟软件ANSYS/LS-DYNA进一步还原夹芯板冲击过程,导出了面板与芯材的吸能占比。基于假设的夹芯板理论模型,给出了平均冲击荷载、局部变形和整体变形最大值的估算公式。结果表明:当夹芯板尺寸和材料强度一定时,局部变形值与落锤高度的平方根成正比,整体变形最大值、平均冲击力均与落锤高度的平方根成线性关系。夹芯板的抗冲击性能主要依靠增大泡沫铝芯层的变形进行耗能,芯层越厚,泡沫铝吸能占比越大,局部变形越小,夹芯板受到的冲击力越大。     

Effect of interfacial bonding strength on tensile ductility of multilayered steel composites

The effect of the bonding strength of the laminate interface on ductility in the tensile deformation of multilayered steel composites was investigated. Multilayered steel composites consisting of alternating layers of as-quenched martensitic and austenitic steels were prepared with various bonding strengths, ranging from weak bonding obtained by alpha-cyanoacrylate adhesive to strong bonding obtained by cold rolling with a subsequent heat treatment. Tensile tests and peel tests were conducted to investigate the relationship between tensile behavior and bonding strength at the interface. It was demonstrated that tensile ductility could be markedly enhanced as the bonding strength increased, and that three types of tensile fracture behavior were identified depending on the bonding strength of the interface.     

NOTCHED FATIGUE BEHAVIOUR OF TWO COLD ROLLED STEELS

Abstract— A SAE1010 plain carbon steel and a SAE945X HSLA steel were cold rolled to various thickness reductions. Centre notched specimens were tested under stress control at a stress ratio of—1. The effect of loading direction on the fatigue strength was examined. The notched specimen fatigue strength was only slightly increased by cold rolling, since two opposing factors: the smooth specimen fatigue strength and the notch sensitivity, were increased by cold rolling. The notched specimen fatigue strength in the transverse direction was approximately the same as that in the longitudinal direction. An empirical equation and equations derived from fracture mechanics and Neuber's rule were applied to predict the fatigue notch factor for the sharp and blunt notch geometries examined. A reasonable agreement between the predictions and the experimental results was observed for the sharp notches. For the blunt notches, the predicted fatigue notch factors were conservative.     

Effect of interlayer thickness on shear deformation behavior of AA5083 aluminum alloy/SS41 steel plates manufactured by explosive welding

An AA5083 aluminum alloy plate and an SS41 steel plate were cladded by an explosive welding method using an AA1050 aluminum alloy interlayer plate. The effects of the interlayer thickness on the interface morphology and the shear deformation behavior of the cladded plates were studied. The interfacial zone was composed of an intermetallic compound, FeAl₃, formed by the AA1050 interlayer. The intermetallic compound acted as a crack source at the AA1050/SS41 interface, and the thickness and morphology of the interfacial zone were depended on the thickness of the AA1050 interlayer. In a shear deformation test, the crack propagation behavior varied according to the morphologies of the interfacial zone, and the shear strength of the cladded plates decreased with the interlayer thickness.     

Deformation and fracture of polymer/metal composites subjected to cold rolling

Cold rolling of a sandwich composite with a metallic strip inclusion in a polymeric matrix can produce a range of outcomes, including deformation and fracture of the inclusion. Using different material combinations under the same processing parameters, the results ranged from minor deformation, to folding and/or loss of adhesion, and fracture of the inclusion, with fracture particles varying in size and shape. Comparisons are made between the resulting structures after cold rolling of the polymer/metal composite to geological formations. In particular, the fracture particles obtained resemble rock structures known as boudins. The phenomena of boudinage and folding encountered in the cold rolling of polymer/metal composites is similar to that seen in geology formations although the time and size scale of these events are several orders of magnitude apart. The experimental results reported show that cold rolling applied to a polymer/metal sandwiched composite induces deformation and fracture behaviors that depend on the mechanical properties of the constituents, deformation behavior of the polymeric matrices, interfacial adhesion, and process parameters such as rollers speed and nip-gap.     

Effect of cold rolling on microstructure and magnetic properties in a metastable lean duplex stainless steel

Microstructural and magnetic properties changes of a metastable ferritic–austenitic stainless steel due to cold rolling were studied together with the possibility to develop a new ferritic–martensitic stainless steel. In order to reduce costs low-Ni content was maintained in the lean duplex stainless steel considered, making it more susceptible to strain-induced martensitic transformation. In this study a practically complete γ → α′ transformation was found for 80% of thickness reduction, resulting a new two-phase ferritic–α′ martensitic stainless steel. To investigate the structural evolution different values of thickness reduction were applied. Light optical and scanning electron microscopy were performed to characterize the morphology and grain refining of the structure after each rolling step. Martensitic transformation and work hardening were detected and analyzed by studying of magnetic properties (saturation magnetic polarization, relative magnetic permeability, coercivity). Additionally, hardness tests were performed. The results highlighted a strong grain refining and increase in martensitic phase and hardness with increasing cold deformation. A direct relationship between microstructure and magnetic properties was revealed. In particular the reciprocal of relative magnetic permeability and the coercivity increased with martensite content and the amount of cold deformation. Therefore, the possible application of magnetic measurements as non-destructive tests to study microstructural evolution during cold rolling was shown for the steel considered.     

轧制复合三层铝合金板变形规律及力学性能的研究

采用"热轧+中间退火+冷轧+轧后退火"法复合轧制AA1100/AA7075/AA1100三层铝合金板。利用金相、SEM-EDS观察微观组织变化及界面元素扩散,由显微硬度和拉伸试验测定复合板力学性能。结果表明,AA7075层组织呈拉伸纤维状沿轧向分布;热轧包覆率不变,中间退火后包覆率随冷轧应变的增加先减小后几乎不变;结合界面处存在Mg、Zn元素扩散。轧后退火使复合板强度降低、塑性增加,硬度沿厚度方向呈现梯度变化规律。     

高聚物夹层材料对层压减振复合钢板拉伸剪切强度的影响

研究了高聚物夹层材料对层压减振复合钢板的拉伸剪切强度的影响。结果指出，高聚物夹层材料较厚时，层压减振复合钢板的拉伸剪切变形规律与高聚物夹层材料的一致；高聚物夹层厚度较小时，复合钢板的拉伸剪切强度较高。与酚醛树脂氯丁橡胶相比，聚氨酯作夹层的层压减振复合钢板具有较高的拉伸剪切强度。