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通过Gleeble-3800热模拟试验机对我国自主研发的211Z-X新型高强韧铝合金进行了热成形性能研究,探索了该新型铝合金热变形过程中的力学行为与组织演变之间的规律,并建立了该铝合金热成形的本构方程和动态再结晶过程的临界应变模型。在变形温度350~500℃、应变速率0.01~10s-1条件下进行等温压缩实验,由绘制的流变应力曲线可知,变形温度和应变速率对211Z-X高强韧铝合金的流变应力影响显著,表现出正的应变速率敏感性和负的温度敏感性。在不同变形条件下的应变硬化速率与流变应力关系曲线中,存在亚晶与大角度晶界形成的特征拐点,根据热力学不可逆原理和单一参数法进行计算分析,获得了热变形过程中亚晶形成和动态再结晶形成的临界应力σc和临界应变εc值,动态再结晶的临界条件为ε≥εc=2.22x10-5Z0.14107,临界应变εc随着温度补偿应变速率因子的增加而增加。对临界应变的组织进行观察发现,在拉长的晶粒层状结构间有细小的再结晶晶粒形成。
The thermoforming properties of 211Z-X high strength and toughness aluminum alloy independently researched and developed in our country were studied by Gleeble-3800 thermal simulation tester. The laws between the mechanical behavior and microstructure evolution of the new aluminum alloy during thermal deformation were explored. The constitutive equation and critical strain model of dynamic recrystallization of the aluminum alloy were established. The isothermal compression experiments were carried out at deformation temperature of 350 ~ 500 ℃ and strain rate of 0.01 ~ 10s-1. It can be seen from the flow stress curves drawn that the deformation temperature and strain rate have a significant effect on the flow stress of 211Z-X high strength and toughness aluminum alloy , Showing positive strain rate sensitivity and negative temperature sensitivity. In the curves of strain hardening rate and flow stress under different deformation conditions, there are characteristic inflection points formed by subgrain and large angle grain boundaries. According to the thermodynamic irreversible principle and single parameter method, the subgrain The critical stress σc and the critical strain εc of formation and dynamic recrystallization, the critical condition of dynamic recrystallization is ε≥εc = 2.22x10-5Z0.14107, and the critical strain εc increases with the increase of temperature-compensated strain rate factor. Observation of the structure of the critical strain revealed the formation of fine recrystallized grains between elongated grain lamellar structures.