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611.
Spray-formed Al-70%Si(mass fraction) alloys were deformed by compression in the semi-solid state.The effects of the deformation temperature, strain rate and the microstructure were studied. Two strain rates(1 s-1and 0.1 s-1) and six deformation temperatures (600 ℃, 720 ℃ , 780 ℃, 900 ℃, 1 000 ℃ and 1 100 ℃) were chosen. The stress-strain curve exhibits a peak at low strain and then decreases to a plateau before it starts to increase again as the strain increases. The stress required for deformation at lower strain rate and at higher deformation temperatures is less than those at higher strain rate and at lower deformation temperatures. Four mechanisms of semisolid deformation can be used to explain the different behaviors of the stress-strain curves under different conditions. 相似文献
612.
Z. H. Xiao J. R. Luo S. S. Wu D. N. Li Y. W. Mao X. J. Song 《Journal of Materials Engineering and Performance》2004,13(1):60-63
In this paper, a rheo-diecasting process of AZ91D alloy semi-solid slurry produced with a twin-screw stirring mixer was investigated.
The results show that the tensile strength and elongation of the sample made by rheo-diecasting were 37% and 44% higher, respectively,
than those produced by conventional liquid diecasting. The castings fabricated by rheo-diecasting possessed good density with
low shrinkage and could be heat treated. It is a “near-net shape” production process. 相似文献
613.
半固态材料成形技术的研究和应用 总被引:10,自引:0,他引:10
半固态成形具有加工温度低 ,变形抗力小的特点 ,为高效低能实现金属近净成形提供了现实可能。对半固态金属加工的工艺方法进行了论述 ,以期推动其理论研究和工业应用 相似文献
614.
半固态60Si2Mn流变轧制的组织及性能 总被引:2,自引:0,他引:2
对弹簧钢(60Si2Mn)进行1道次的半固态轧制变形,研究半固态浆料轧制前后的组织和性能,明确了在轧制变形中半固态浆料的组织变化规律和轧后的力学性能特征,结果表明:仅经过1道次的半固态轧制变形,兰固态浆料的组织就得到了明显的改善;在半固态浆料中,固相颗粒大多聚集在轧件的中间区域,液相主要流向轧件的边部,从而导致液相偏析,使轧制产品的边部和中部的组织和性能的不同,只有当固相率达到一定数值时,固相颗粒才会发生塑性变形,被压扁拉长。 相似文献
615.
616.
铝硅合金凝固过程中的力学行为和热裂倾向性 总被引:1,自引:1,他引:0
利用自制的准固态力学性能测试装置,对铝硅合金的准固态力学性能进行了较为系统的测试,得出了反映不同含硅量铝硅合金的准固态力学行为参数(强度、断裂应变、准固态区间等),并分析了这些参数与热裂倾向性的关系。 相似文献
617.
WANG Kai LIU Changming HAN Zhaotang CAO Jianyong ZHANG Zonghe 《稀有金属(英文版)》2005,24(4):381-391
The investment on semi-solid die casting processes of AZ91D magnesium alloy brackets for generators in JH70-type motorbikes is introduced. The processes of low super-heat and cooling slope for the preparation of billets with non-dendritic microstructure, the remelting of billets for thixoforming and the parameters in the process of semi-sohd thixoforming have been researched. The results show that primary billets with non-dendritical structures can be prepared by forming great amount of nuclei in melt via the process of low super heat. By optimizing the remelting process through adjusting the current of the induced equipment, semi-solid billets with a structure of spherical grains were obtained from the primary billets with non-dendritical structure. The range of 580℃ to 583℃ is the proper remelting temperatures by which the billets have an expected thixotropy and can be transferred to a die-casting machine. The optimized parameters of semi-solid forming in a die-casting machine are as follows: the area of the ingate in the die is 383.5 mm^2, the speed of the pierce of the machine 5 m/s, the shot pressure of the pierce 75 MPa, and the maintenance pressure of the pierce 350 MPa. The castings of brackets for supporting generators in JH70 type motorbikes were formed by adopting the optimized processes and parameters mentioned above. 相似文献
618.
Microstructure of electromagnetic stirred semi-solid AZ91D alloy 总被引:4,自引:0,他引:4
The microstructures of semi-solid AZ91D alloy stirred by rotationally electromagnetic field were studied.The shape of primary α-Mg phase is dendrite under conventional solidification condition and the primary α-Mg grains are changed to the fine rosette-like or granular grains under electromagnetic stirring condition. If the electromagnetic stirring frequencies are low, there are a large amount of fine rosette-like primary α-Mg grains and the fine rosettelike primary α-Mg grain in two dimensions belongs to a single grain in three dimensions; there are also many spherical primary α-Mg grains, they may belong to a single grain in three dimensions and the orientation differences of the grains between them are very small. If the electromagnetic stirring frequencies are high, a lot of the fine rosette-like primary α-Mg grains disappear and are converted into granular grains, and moreover, most of these granular grains belong to different grains in three dimensions. 相似文献
619.
620.