同步、异步组合轧制取向硅钢极薄带的织构研究

采用同步、异步组合轧制方式将成品工业取向硅钢板冷轧到0.08mm,然后在纯氢气炉中高温退火,采用ODF和反极图定量分析硅钢薄带的冷轧和再结晶织构。研究结果表明,在同步、异步组合轧制方式下,冷轧薄带的变形织构与一般常规冷轧板的相同,但沿板厚呈现了不对称分布,经840℃保温6h退火,晶粒取向为集中的{110}〈001〉。

工程法与滑移线场组合解析立轧轧制力

提出以工程法与滑移线场组合求解粗轧过程立轧轧制力的方法。基于立轧的变形特点,绘制出经立轧道次后轧件塑性区的滑移线场,根据立轧中狗骨区滑移线场的几何特点,确定了立轧后塑性区的最大深度。然后应用工程法在轧件塑性区域内建立力平衡微分方程并联解屈服条件得出立轧轧制力的解析解,并对此立轧轧制力模型的物理意义进行分析。使用有限元模拟对立轧变形规律进行总结并与组合解法解得的立轧轧制力模型进行比较,误差较小,验证了此轧制力模型的物理意义。将建立的力学模型预测的轧制力与实测数据比较,误差不超过10%。

不同构造的轧制型材组合异形柱短柱轴压力学性能研究

为研究轧制型材组合异形柱在轴向荷载作用下的受力性能,采用ABAQUS软件平台建立不同构造、是否填充混凝土的组合异形柱短柱试件有限元模型。基于现有试验结果验证了建模方法的准确性,揭示了其在轴压荷载作用下的承载性能、破坏模式和受力机理,并分析了不同构造、是否填充混凝土对其轴压性能的影响规律。研究结果表明,轧制型材组合异形柱均为整体受压破坏,伴随钢管局部屈曲破坏;填充混凝土后能够明显改善组合异形柱的破坏模式,提高承载力;纯H型钢组合试件采用封口板形成闭口截面后承载力提升显著。采用现有标准/规范对轧制型材组合异形柱的承载力进行计算,相对差值在11%以内,计算值与模拟值吻合较好,计算值能够较好预测轧制型材组合异形柱短柱的轴压承载力。

Interface analysis of 7B52 Al alloy laminated composite fabricated by hot-roll bonding

The bonding interface of 7B52 Al alloy laminated composite （ALC） fabricated by hot rolling was investigated using optical microscopy （OM）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, ultrasonic flaw detection （UFD）, and bonding strength tests. The results show that metallurgical bonding is achieved at the interface after composite rolling. The TEM analysis and tensile tests indicate that the 7B52 ALC plate combines high strength of the hard individual layer and good toughness of the soft individual layer. However, UFD technology and SEM analysis prove that the defects （thick oxide films, acid washed residues, air, oil and coarse particles） existing in the bonding interface are harmful to the bonding strength. To sum up, the composite roiling process is suitable for 7B52 ALC plate, and the content and size of the defects should be controlled strictly. Advanced surface treatment of each individual layer would be beneficial to further improve the bonding quality.

Effects of rolling and annealing on microstructures and properties of Cu-Mg-Te-Y alloy

Microstructures and element distributions of the as-cast, hot-rolled and cold-rolled Cu-Mg-Te-Y alloys were studied. Effects of rolling process and annealing temperature on the properties of the Cu-Mg-Te-Y alloys were correspondingly investigated. The results indicate that the Mg element is homogeneously distributed in the matrix and the fragmentized Cu2Te phase is dispersed in the matrix after hot rolling. Then, the Cu2Te phase is further stretched to strip shape after the cold rolling process. The microstructures of the cold-rolled alloy keep unchanged for the sample annealed below 390 ℃ for 1 h. However, after annealing at 550 ℃ for 1 h, the copper alloy with fibrous microstructures formed during the cold rolling process recrystallizes, leading to an obvious drop of hardening effect and an increase of electrical conductivity. The Cu-Mg-Te-Y alloy with better comprehensive properties is obtained by annealing at 360-390 ℃.

室温下金属铝的组合成形轧制

轧辊的弹性变形导致金属极薄带难以通过常规方法制备,人们想尽各种办法来获得更薄的轧件,如减小轧辊直径、增加支撑轧数量、增加轧辊和机架刚度等,这些方法使极薄带的制备变得复杂.本文采用组合成形轧制(combination forming rolling, CFR)新方法,将常规轧制的压缩作用、异步轧制的搓轧剪切作用和施加大张力的拉伸作用等三种工艺措施共同作用于轧制变形区,构造出易于满足屈服条件的应力状态,保持压下变形的可持续性.为了验证这种方法的可行性,在室温下对退火态工业纯铝板进行了组合成形轧制.实验结果表明,在没有中间退火的情况下,初始厚度为6.5 mm的1100铝板轧制成厚度为17μm极薄带,产品表面光滑、板形良好、无边缘裂纹,组合成形轧制的延展率达到38235%,真应变为5.95,充分体现出组合成形超强的变形能力.在剧烈塑性变形发生的同时,金属Al内部的显微组织也随之发生演变,由原始粗大的等轴晶演变为扁平的板条晶、亚微晶,直至出现纳米晶.以大应变、超延展、纳米化为特征的组合成形轧制将成为剧烈塑性变形中一个重要的新方法.

Microstructure evolution and mechanical properties of Cu-0.36Be-0.46Co alloy fabricated by heating-cooling combined mold horizontal continuous casting during cold rolling

Cu-0.36 wt.%Be-0.46 wt.%Co alloy plate with 300 mm in width and 10 mm in thickness prepared by heating-cooling combined mold(HCCM) horizontal continuous casting was cold rolled. Microstructure evolution and mechanical properties of the alloy as well as its deformation mechanism were investigated. The results showed that the as-cast alloy plate had columnar grains along the length direction, good surface quality and elongation of 35%, which was directly large-reduction cold rolled without surface treatment, and the accumulative cold rolling reduction reached 98%. When the reduction was small(20%), numerous dislocations and dislocation cells formed, and the deformation mechanism was dislocation slip. When the reduction was 40%, deformation twins appeared, and interactions between twins and dislocation cells induced strip-like dislocation cells. When the reduction exceeded 60%, shear bands formed and apparent crystal rotation in the micro-region happened. Further increasing the reduction, the amount of the shear bands rose and they interacted with each other, which refined the grains apparently. The tensile strength and hardness increased from 353 MPa and HV 119 of the as-cast alloy to 625 MPa and HV 208 with 95% reduction, respectively, and the elongation reduced from 35% to 7.6%. A process of HCCM horizontal continuous casting-cold rolling can work as a novel compact method to fabricate Cu-Be alloy sheet.

Effect of cryorolling on microstructure and property of high strength and high conductivity Cu−0.5wt.%Cr alloy

Cu−0.5wt.%Cr alloy with high strength and high conductivity was processed by cryorolling(CR)and room temperature rolling(RTR),respectively.The microstructure,mechanical property and electrical conductivity of Cu−0.5Cr alloy after CR/RTR and aging treatment were investigated.The results indicate that obvious dislocation entanglement can be observed in matrix of CR alloy.The Cr particles in the alloy after CR and aging treatment possess finer particle size and exhibit dispersive distribution.The peak hardness of CR alloy is HV 167.4,significantly higher than that of RTR alloy.The optimum mechanical property of CR alloy is obtained after aging at 450℃ for 120 min.The conductivity of CR Cu−0.5Cr alloy reaches 92.5%IACS after aging at 450℃ for 120 min,which is slightly higher than that of RTR alloy.

Microstructural evolution in Al-Zn eutectoid alloy by hot-rolling

The Al-Zn eutectoid alloy has been widely known as a typical superplastic metallic material, where fine-grained microstructure is usually obtained by heat treatment. Recently, thermo-mechanical controlled process has also been reported to provide a fine-grained microstructure. In the present study, Al-Zn alloy ingots of 20 mm in thickness were homogenized and hot-rolled to a thickness of 2 mm under three processes： 1） the specimen was air-cooled after homogenization and hot-rolled; 2） the specimen was water-quenched after homogenization and hot-rolled; 3） the specimen was immediately hot-rolled after homogenization. Microstructural observation showed that, in processes l and 3, lamellar microstructure was formed after homogenization, and became fragmented to fine-grained microstructure as the hot roiling process proceeded. In process 2, fine-grained microstructure without lamellar microstructure was attained throughout the hot-rolling process. A minimum grain size of 1.6 μm was obtained in process 3. Tensile tests at room temperature showed that the elongation to failure was the largest in process 3.