排序方式: 共有34条查询结果,搜索用时 15 毫秒
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半固态坯的流动性能是获得优质、复杂制件的基础和关键。通过对两种状态合金在相同载荷作用下进行半固态压缩试验,结果表明:挤压态合金的流动性最差,挤压后冷变形态合金Ⅱ(压缩方向垂直于冷变形方向)的流动性最好。这主要有两方面的原因:一是晶粒形状上的差异;二是与半固态坯料的制备历史及其后续加工有关。 相似文献
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The effects of compression ratios on the microstructure evolution of semisolid Al7075 alloy produced by the strain induced melt activation (SIMA) process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments within mushy zone of the alloy were carried out at 610, 620 and 625 °C for predetermined time intervals.The results revealed that the average grain size gradually reduced with the increase in the compressive ratio. While the compressive ratio surpassed 30%, the descending trend above was not as evident as that of below 30% reduction. The optimum condition presenting the minimum grain size and the maximum shape factor with the highest uniformity is discussed. During the subsequent mushy zone heating, the recrystallization was induced in the deformed samples by the increasingly accumulated strain energy. 相似文献
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E. ParshizfardS.G. Shabestari 《Journal of Alloys and Compounds》2011,509(40):9654-9658
Microstructural evolution and tensile properties of thixoformed near net shape parts of A380 aluminum alloy have been studied. The effect of plastic deformation and holding time in the appropriate semi-solid temperature has been investigated in the strain-induced melt activating process (SIMA). The results of image analysis showed that by increasing the deformation value from 5% to 11%, the recrystallized α-Al grains gradually refined as a result of the increasing the nucleation rate. At the value of 11% plastic deformation a dominant globular structure of α-Al grains was obtained. However, further increasing in the plastic deformation (14%) reduced considerably the shape factor. The equivalent diameter and the shape factor of the globular grains were 70.3 μm and 79%, respectively, after about 11% of plastic deformation. Holding time of the specimens at the semi-solid temperature has been studied from zero to 30 min. It was found that the holding time of 25 min is the best to prevent grain growth. The mechanical properties of thixoformed alloys were also investigated. The results showed that the yield, tensile strength and elongation have been increased considerably using thixoforming, compared with the as-cast condition. 相似文献
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等径道角挤压在AZ91D镁合金半固态加工中的应用 总被引:1,自引:0,他引:1
将等径道角挤压工艺(ECAE)应用为应变诱导-熔化激活(SIMA)中的应变诱导工序,并且利用半固态等温处理对ECAE挤压的材料实现熔化激活,提出新SIMA制备AZ91D镁合金半固态坯方法。研究结果表明,新SIMA法制备的AZ91D半固态坯的微观组织均匀、晶粒球化程度好、晶粒细小,平均晶粒尺寸在20μm左右。新SIMA法所制备的半固态坯料半固态触变模锻成形的托弹板的力学性能高,其抗拉强度达到293.5MPa,延伸率达到14.28%。 相似文献
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应变诱发AZ91D镁合金半固态组织形态及形成机理 总被引:12,自引:2,他引:12
采用应变诱发方法制备了AZ91D镁合金半固态材料。考察了变形率、温度、保温时间对固相体积分数、组织形态以及晶粒尺寸的影响。结果表明:在冷变形条件下.于570℃保温一定时间后。可制备出固相体积分数最小达55%的镁合金半固态材料。分析讨论了AZ91D镁合金半固态组织的形成机理。在热处理过程中,组织发生再结晶,而冷变形程度对再结晶的组织有显著影响。 相似文献
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工艺参数对半固态Al-4Cu-Mg合金微观组织与性能的影响 总被引:2,自引:1,他引:2
采用应变诱发熔化激活工艺(SIMA)制备了半固态Al-4Cu-Mg合金,并对其组织性能进行了研究。结果表明:通过合理选择SIMA工艺参数,能够得到晶粒尺寸小且呈近球状的半固态组织;SIMA工艺参数对晶粒的大小和形状产生较大的影响。变形量越大、等温温度越低和保温时间越短,晶粒尺寸越小;变形量越大、等温温度越高和保温时间越长,分形维数越小,晶粒越圆整;采用变形量为20%~25%、等温温度为580~600℃和保温时间为2~6min的合理SIMA工艺参数,可获得室温抗压强度和屈服强度分别为358~387MPa和246-265MPa的半固态材料。 相似文献
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变形程度对7A04合金半固态触变组织的影响 总被引:1,自引:1,他引:0
获得具有触变特性的均匀的、近球形的显微组织是半固态触变成形工艺的基础和关键。以挤压态7A04合金SIMA法生成触变组织为例.研究变形程度对其半固态触变组织的影响。结果表明:在加热前的变形程度对显微组织的影响很大,随着变形程度的增加,晶粒尺寸减小,晶粒形状越趋于球形;当变形程度超过0.3时,晶粒尺寸及其球形化速度逐渐减慢并趋于稳定值。此外,经过冷变形后,晶粒内及晶粒间的偏析减小,晶界易被低熔点液相浸润.更易获得均匀的、近球形的触变组织。 相似文献