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累积叠轧焊温度和循环道次对AZ31镁合金组织和性能的影响 总被引:1,自引:0,他引:1
研究了累积叠轧焊温度变化和循环道次对AZ31镁合金板材组织和性能的影响,分析了累积叠轧焊工艺细化AZ31镁合金晶粒的机理.试验结果表明,加热温度从250℃增加到400℃时,第一个道次后的平均晶粒尺寸逐渐减小;在400℃保温5min、道次压下量为50%时,第二个道次的板材平均晶粒尺寸可以细化到1.3μm,抗拉强度为300MPa,伸长率达到25.2%. 相似文献
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采用了金相、电子背散射衍射(EBSD)、硬度、拉伸、杯突等试验手段研究了累积叠轧AA3003铝合金板材退火处理后的微观组织和性能。结果表明,叠轧板材在退火过程中晶粒等轴化,叠轧道次越高,退火后晶粒越细小,且退火能促使叠轧板材界面的焊合。叠轧4道次的板材随着退火温度的提高,逐渐发生再结晶和晶粒长大,强度和硬度性能逐渐降低并趋于平稳,塑性和成形性能则逐渐改善。叠轧4道次的板材再结晶完成温度约为346℃,温度低于350℃时,厚向晶粒尺寸比较均匀,但表面层和中心层织构存在明显差异;温度达到450℃时,表面层的晶粒尺寸要明显大于中心层,厚度方向组织不均匀性加大,但其织构趋于一致。 相似文献
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采用累积叠轧工艺制备了1 mm厚的Al-Mn和Al-Mn-Er-Zr合金,研究了累积叠轧道次对Al-Mn和Al-Mn-Er-Zr合金显微组织、拉伸性能、显微硬度和微观结构的影响,分析了累积叠轧和微量元素Er、Zr的作用机理。结果表明:随着累积叠轧道次的增加,Al-Mn和Al-Mn-Er-Zr合金板的界面结合数不断增加,界面结合质量有所提高,且相同累积叠轧道次下Al-Mn-Er-Zr合金板的界面结合质量更好;累积叠轧后Al-Mn和Al-Mn-Er-Zr合金板的强度相较于叠轧前有所提高,断后伸长率有所减小,而随着累积叠轧道次增加,强度和硬度不断增大而塑性变化较小;在相同的叠轧道次下,Al-Mn-Er-Zr合金的强度和硬度都要高于Al-Mn合金; Al-Mn和Al-Mn-Er-Zr合金叠轧后都会在形变区域形成亚晶和位错胞,且随着累积叠轧道次的增加,位错胞会逐渐转变为细小晶粒;相同叠轧道次下Al-Mn-Er-Zr合金中位错和亚晶密度会更高,这与Al-Mn-Er-Zr合金中形成了细小的钉扎位错和晶界的颗粒状Al3Er相有关。 相似文献
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通过光学显微镜、室温拉伸试验、显微硬度计、X射线衍射仪、扫描电镜等方法研究了累积叠轧温度对AZ31镁合金晶粒尺寸、基面织构、界面结合情况及力学性能的影响。结果表明:3道次累积叠轧后的AZ31镁合金晶粒细化效果明显,硬度增大,随着累积叠轧温度的升高,晶粒细化效果减弱,硬度增加趋势减弱。累积叠轧温度升高有弱化基面织构的作用。AZ31镁合板材在450 ℃累积叠轧3道次,综合力学性能最佳,为显微硬度70.64 HV0.05,抗拉强度288.64 MPa,屈服强度203.76 MPa,伸长率16.96%,界面结合强度21.53 MPa。 相似文献
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《中国有色金属学会会刊》2019,(3)
研究一种新的剧烈塑性变形技术,即累积挤压结合(AEB)加工超细晶粒铝。显微组织表征结果表明,界面结合良好,6道次后样品的平均晶粒尺寸约为440 nm。拉伸试验结果表明,5道次后样品的抗拉强度达到最大值195 MPa,总伸长率超过16%;样品的硬度也显著提高,且在第1道次后几乎达到饱和。累积挤压加工的样品经拉伸试验后的扫描电镜断口形貌表明,断裂模式为剪切韧性断裂,同时出现细长浅韧窝。与传统累积叠轧工艺相比,此新型累积挤压技术在细化晶粒和改善力学性能方面更有效。 相似文献
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突破传统ECAP变形全过程通道等截面思路,提出一种耦合剪切应变和正应变于一体的新型等通道球形转角挤压(equal channel angular extrusion with spherical cavity,ECAE-SC)工艺。在自行研制的模具上对工业纯铝进行室温单道次ECAE-SC挤压实验,采用OM、EBSD和TEM等技术手段,研究了ECAE-SC变形过程中工业纯铝微观组织的演变规律,并测试了变形后试样的显微硬度。结果表明,在ECAE-SC工艺剧烈简单剪切变形诱导下,工业纯铝仅需1道次挤压变形即可获得等轴、细小、均匀的超细晶组织,平均晶粒尺寸约为400 nm;工业纯铝室温ECAE-SC变形以位错滑移为主并伴有不完全连续动态再结晶,其微观组织经历了剪切带→位错胞→小角度亚晶→大角度等轴晶粒等动态演化过程。1道次ECAE-SC变形后,工业纯铝组织以{110}001高斯织构为主,同时存在部分{111}112铜型织构;材料显微硬度值大幅提升,由初始289.4 MPa提高到565.3 MPa,增幅高达95.33%,且分布均匀性良好。 相似文献
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对传统等通道转角挤压工艺(equal channel angular extrusion,ECAE)进行改进,提出一种新型剧烈塑性变形法(severe plastic deformation,SPD)——等通道球形转角膨胀挤压(equal channel angular expansion extrusion with... 相似文献
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铝合金法兰辗制工艺是通过连续局部塑性变形的积累使法兰整体壁厚减小、直径扩大、截面轮廓成形,最终使环件毛坯成为一定形状尺寸的法兰零件。法兰件辗制过程中,局部变形区存在厚度减小、周向伸长、轴向宽展的塑性变形,这种塑性变形的发生、发展和积累规律决定了法兰辗制变形和成形是渐变的,极大地减少了法兰开裂的倾向。本文通过对铝合金法兰辗制工艺的关键技术进行研究,成功实现批量生产。 相似文献
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《Acta Materialia》2001,49(13):2583-2595
Asymmetric rolling, in which the circumferential velocities of working rolls are different, imposes shear deformation and in turn shear deformation textures to sheets through the thickness. A component of ND//〈111〉 in the shear deformation textures can improve the plastic strain ratios of aluminum sheets. In order to understand the evolution of ND//〈111〉, the strain histories and distributions in the sheets and the texture evolution during the asymmetric rolling have been measured and calculated. The shear deformation texture can vary with the ratio of shear to normal strain increments. As the ratio increases from zero to infinity, the texture moves from the plane strain compression texture (β fiber) to the ideal shear deformation texture consisting of {001}〈110〉, {111}〈110〉, and {111}〈112〉. The ratio increases with rolling reduction per pass in asymmetric rolling. However, it is practically difficult to develop a rolling reduction per pass high enough to obtain the ideal shear deformation texture. Imposing the positive and negative shear deformations on the sheet by reversal of the shearing direction can give rise to the ideal shear deformation texture. 相似文献
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室温下,对923 及1023 K退火1 h所得的不同原始晶粒尺寸的工业纯钛进行ECAP变形。通过TEM、EBSD、室温拉伸和显微硬度测试研究原始晶粒尺寸对ECAP变形纯钛组织性能的影响。探讨纯钛ECAP变形孪生行为和变形机制。结果表明,退火温度越高,原始晶粒尺寸越大。1道次变形后,1023 K退火纯钛的晶粒细化效果更显著。4道次变形后,923 K退火纯钛的组织更细小均匀。随着变形道次的增加,屈服强度不断增大,1道次变形后增幅最大,约为100%,且原始晶粒尺寸越大,强度增幅越大。纯钛ECAP变形机制包括位错滑移和孪生,原始晶粒尺寸越大,孪晶数量越多。 相似文献
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Asymmetric rolling(ASR), as one of severe plastic deformation(SPD) methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymmetric rolling with pure aluminium as a model material. Effects of reduction ratio and mismatch ratio on the shear deformation were studied. With the observed shear deformation results, equivalent strain was calculated. For lager shear deformation, rolling equipment was modified to increase friction between specimen and the rollers. Consequently, extremely fine grains with size of 500 nm are obtained in pure aluminium. With improved asymmetric rolling, the ability of grain refinement of ASR is greatly improved. 相似文献
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Hongtao DingNinggang Shen Yung C. Shin 《Journal of Materials Processing Technology》2012,212(5):1003-1013
Recently, grain refinement and grain misorientation have been experimentally studied for various materials with ultra-fine grained microstructures, which are achieved by the multi-pass cold rolling process. In this paper, a numerical framework is developed to model the evolution of grain size and grain misorientation based on a dislocation density-based material model. Novel finite element models embedded with the dislocation density-based material subroutine are developed to model the plastic deformation and microstructural evolution during the multi-pass cold rolling process. The multi-pass cold rolling processes of commercially pure titanium (CP Ti) and aluminum (AA 1200) are simulated in order to assess the validity of the numerical solution through comparison with experiments. The dislocation density-based material models are developed for CP Ti and AA 1200, which reproduce the observed material constitutive mechanical behavior under various strains, strain rates and temperatures occurring in the cold rolling process. It is shown that the developed model captures the essential features of the material mechanical behaviors and predicts a minimum grain size of below 100 nm after five-pass cold rolling of CP Ti with equivalent strains up to 2.07 and the average incidental dislocation boundary (IDB) misorientation angle increased to 4.6° after six-pass cold rolling of AA 1200 with equivalent strains accumulated to 5.77. 相似文献