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The microstructures of ZK60 alloy under conventional direct as-casting (DC),twin roll casting (TRC) and twin roll casting followed by hot compression (TRC-HC) were analyzed by optical morphology (OM),electron backscatter diffraction (EBSD) and X-ray diffraction (XRD).The deformation condition of hot compression is 350 ℃,0.1 s?1.The microstructural evolution under TRC-HC deformation followed by annealing at different temperatures and time was discussed.The results show that TRC provides more modified microstructure compared with DC.Twins are found in TRC processing;dynamic recrystallization (DRX),shear bands and twins are found in TRC-HC.A short annealing time has little effect on hardness,while during a long time annealing,it is found that low annealing temperatures increase the micro-hardness and high temperature decreases it. 相似文献
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This work explores the microstructure of low frequency electromagnetic casting (LFEC) 7075 aluminum alloys and investigates the effect of heat treatment process on its mechanical properties via the mechanical properties test, X-ray diffraction and transmission electron microscopy. It was found that the grains of LFEC ingot were finer and more evenly distributed than that of the conventional direct chill cast (DC) ingots. The microstructure of LFEC ingot extruded kept their original as-cast structure with small and fine grains. With the same extrusion ratio, the average grain diameters of LFEC and conventional DC extruded were about 10 and 20 μm, respectively. LFEC extruded also had a better aging property, since the regime of T6 treatment peak value aging was at 120 C for 24 h, the tensile strength and hardness (HV) of the LFEC extruded were 673.50 MPa and 194.62, respectively, which were all higher than those of the conventional DC extruded, indicating that the process regime can be applied in the industrial production. 相似文献
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Qingfeng ZHU Zhihao ZHAO Jianzhong CUI Xiangjie WANG Ke QIN Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang China 《金属学报(英文版)》2011,(5):399-404
7075 aluminum alloy ingot with the diameter of 100 mm has been produced by hor-izontal direct chill casting in different casting speed. The effect of the casting speed on the ingot surface and subsurface layer was studied by surface observation and subsurface structure analysis. It was found that increasing the casting speed results in the adding of segregation knots in the ingot surface. The thickness of the dendrite microstructure layer in the subsurface reduces with increasing the casting speed. And the ... 相似文献
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研究了超声波对双辊铸轧的Mg-3wt%Al-1%Zn-0.8?-0.3%Mn合金板带材组织和性能的影响。实验结果表明:超声波辅助镁合金的铸轧可以提高镁合金带材的强度、延伸率和极限深拉比值,在250℃镁合金带材的极限深拉比值可以达到2.16。这些镁合金力学性能和成形能力的提升是由于超声波铸轧过程中,超声波可以细化镁基体的晶粒尺寸,并同时对合金中的Mg17(Al,Zn)12和AlCeMn相起到变质作用。当超声波强度达到800W时,镁基体的晶粒尺寸可以从150μm细化到30μm,而且针状的AlCeMn相可以被变质成球状,从而提高了镁合金的力学性能和成形能力。 相似文献
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参照工业多流半连续铸造结构,设计了试验用单流半连续铸造铝合金设备,并使用该设备进行半连续铸造7075铝合金,为工业多流半连续铸造提供试验基础。对比研究了铸造速度、热顶结构等对铸锭表面质量的影响。研究发现:提高铸造速度仅仅能减弱冷隔,而无法消除冷隔;降低临界铸造速度虽然能得到光洁表面的铸锭,但无法进行稳定长时间半连续铸造,无法在工业上应用;减少overhang无法解决铸锭表面质量问题;热顶与结晶器之间的三角区被润滑剂填充后,能够实现稳定半连续铸造,并得到表面质量合格的铸锭。 相似文献
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Dynamic modeling of twin roll casting AZ41 magnesium alloy during hot compression processing 总被引:1,自引:0,他引:1
A dynamic material model of Mg-4.51Al-1.19Zn-0.5Mn-0.5Ca(AZ41,mass fraction,%)magnesium alloy was put forward.The results show that the dynamic material model can characterize the deformation behavior and microstructure evolution and describe the relations among flow stress,strain,strain rates and deformation temperatures.Statistical analysis shows the validity of the proposed model.The model predicts that lower deformation temperature and higher strain rate cause the sharp strain hardening. Meanwhile,the flow stress curve turns into a steady state at high temperature and lower strain rate.The moderate temperature of 350 ℃and strain rate of 0.01 s-1 are appropriate to this alloy. 相似文献
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E. S. Puchi-Cabrera C. J. Villalobos-Gutiérrez A. Carrillo F. Di Simone 《Journal of Materials Engineering and Performance》2003,12(3):261-271
It is shown that the recrystallization behavior of a cold rolled twin roll cast, commercial 3003 aluminum alloy under non-isothermal
conditions, can be satisfactorily modeled by combining the approaches developed by Semiatin et al. and Puchi et al. The first
approach allows the determination of the apparent activation energy for recrystallization without any ambiguity, information
that can then be used in the second approach to define clearly the search range for the value of the apparent activation energy
for recrystallization and to determine simultaneously the Avrami constants, from experiments conducted at a single heating
rate. It is also shown that the apparent activation energy for recrystallization in this alloy varies between approximately
34 and 79 kJ/mol, with the trend being to find smaller values of this parameter as the strain applied to the material increases.
Such low values of this energy were corroborated by isothermal experiments conducted in samples of the same material. The
microstructural evolution of the samples annealed under non-isothermal conditions indicates that the rate of growth of the
recrystallized grains in the rolling direction is significantly higher that in the short transverse direction, due to the
pinning effect of the second phase particles aligned along the rolling direction, which leads to recrystallized structures
with an aspect ratio significantly higher than 1. The effect of the strain applied to the material on the recrystallization
kinetics is quantified by expressing the time required to achieve a given recrystallized fraction as a function of the effective
strain, by a simple parametric relationship that involves three numerical constants. Recrystallization experiments conducted
under non-isothermal conditions are found to be more suitable for the evaluation of the effect of the strain applied on the
recrystallization kinetics in comparison with isothermal tests, since larger strains can be applied to material before the
annealing treatment. 相似文献
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铝合金的超常铸轧制备 总被引:8,自引:0,他引:8
钟掘 《中国有色金属学报》2004,14(Z1):147-153
铝合金连续铸轧以其短流程、高效、节能等突出的优势成为铝板带热轧坯的主要生产模式之一,特别是在我国其产量已大于热轧板.因此,提高其产品质量和生产效率成为十分突出的普遍问题.提出"超常铸轧"技术思路,通过强化铸轧环境,改变铸轧工艺,使铝合金铸轧组织发生新的演变,板材性能全面改善,成型性有显著提高."超常铸轧"的核心技术是:1)基于高能量密度输运的热传导技术;2)基于外加瞬时随机变化磁场的铸轧区熔体强微扰动技术.研究了两种新技术的科学原理和技术要素. 相似文献
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Tahar Sahraoui Mohamed Hadji Nacer Bacha Riad Badji 《Journal of Materials Engineering and Performance》2003,12(4):398-401
A study has been made to investigate the effect of a prior amount of warm rolling on the superplastic forming behavior of
a standard grade 7075 aluminum alloy. The thermomechanical treatment process presented for grain refinement includes furnace
cooling from the solution treatment temperature to the overaging temperature, warm rolling from 65–85% deformation, recrystallization,
and artificial aging treatment. Increasing the amount of warm rolling beyond 80% deformation does not produce material with
higher elongation to failure when the thermomechanical treatment process presented is used. The largest value of elongation
to failure was 700%, which was obtained for a specimen having a grain size of 8 μm at a strain rate of 6×10−3S−1. The fracture surface exhibits a granular appearance indicative of an intergranular fracture mode. Dislocation activities
within grains were observed, indicating the occurrence of dislocation slip during grain boundary sliding. 相似文献
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液相线半连续铸造7075铝合金触变成型力的工程法求解 总被引:1,自引:0,他引:1
采用工程法和近似塑性条件dσr=dσz, 并将接触面假设为混合摩擦条件, 对液相线半连续铸造法获得的7075铝合金半固态浆料的触变成型力进行了计算. 计算结果表明 在变形的开始阶段, 成型力为32kN; 在变形的终了阶段, 成型力为667.09kN, 与实测结果721kN基本符合. 相似文献
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Microstructural evolution and mechanical properties of twin roll cast (TRC) Mg-3.3 wt.%Al-0.8 wt.%Mn-0.2 wt.%Ca (AM31 + 0.2Ca) alloy strip during warm rolling and subsequent annealing were investigated in this paper. The as-TRC alloy strip shows columnar dendrites in surface and equiaxed dendrites in center regions, as well as finely dispersed primary Al8Mn5 particles on interdendritic boundaries which result in the beneficial effect on microstructural refinement of strip casting. The warm rolled sheets show intensively deformed band or shear band structures, as well as finely and homogeneously dispersed Al-Mn particles. No evident dynamic recrystallization (DRX) takes place during warm rolling process, which is more likely attributed to the finely dispersed particle and high solid solution of Al and Mn atoms in α-Mg matrix. After annealing at 350 °C for 1 h, the warm rolled TRC sheets show fine equiaxed grains around 7.8 μm in average size. It has been shown that the present TRC alloy sheet has superior tensile strength and comparative elongation compared to commercial ingot cast (IC) one, suggesting the possibility of the development of wrought magnesium alloy sheets by twin roll strip casting processing. The microstructural evolution during warm rolling and subsequent annealing as well as the resulting tensile properties were analyzed and discussed. 相似文献
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The residual stresses distribution of 7075 aluminum alloy in vacuum electron beam welding joint was numerically simulated using nonlinear finite element method. The result shows that the longitudinal residual stress is tension stress along weld center and the stress peak value appears in the middle of the welded seam; the transversal residual stress is compression stress ; the residual stress in thickness direction is very small. 相似文献
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《CIRP Annals》2022,71(1):221-224
The work concerns the possibility of producing B-pillars from the 7075 aluminum alloy. First, extensive material tests were carried out. The as-delivered sheets (T6 temper) were heated up to 500 °C and solution heat-treated to dissolve the phases in the aluminum matrix. Then, the foot of the B-pillar was stamped from water-cooled and conductively-cooled blanks. When the initial process parameters were established, stamping tests of B-pillars were carried out. The strength and hardness of the manufactured elements were tested. The selection of process parameters allowed to obtain a product with an appropriate strength, similar to the strength of the T6 temper. 相似文献
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Rheo-squeeze casting of semi-solid A356 aluminum alloy slurry 总被引:1,自引:0,他引:1
The effect of pouring temperature, electromagnetic stirring power and holding process on semi-solid A356 aluminum alloy slurry was investigated, then the slurry was squeeze-cast. The results show that when the pouring temperatures are properly above the liquidus line, for example 630-650 °C, the slurry with spherical primary α(Al) grains can be prepared under the stirring power of 1.27 kW. The slurry is then homogeneously held for a short time, and the primary α(Al) grains are further ripened and distributed evenly in the slurry. The results of the rheo-squeezed casting experiments show that the injection specific pressure has a great effect on the filling ability of the semi-solid A356 aluminum alloy slurry, and the higher the injection specific pressure is, the better the ability for the slurry to fill the mould cavity is. When the injection specific pressure is equal to or above 34 MPa, the whole and compact rheo-squeezed castings can be obtained. The microstructure of the castings indicates that the shape, size and numbers of the primary α(Al) grains in different parts of the castings are highly consistent. After being held at 535 °C for 5 h and then aged at 155 °C for 12 h, the ultimate strength of the rheo-squeezed castings can reach 300-320 MPa, the yield strength 230-255 MPa, and the elongation 11%-15%. 相似文献