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粗晶U720Li合金热变形行为与动态再结晶特点
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1.西北有色金属研究院;2.西部超导材料科技股份有限公司

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中国博士后基金面上项目(项目号2017M623333XB),陕西省博士后基金(项目号2018BSHQYXMZZ34),西安市未央区科技计划(项目号201701)


Deformation behavior and dynamic recrystallization characteristic of a coarse U720Li alloy
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    摘要:

    为了模拟难变形镍基高温合金GH4720Li开坯锻造过程,采用Gleeble-3800热模拟试验机研究经均匀化处理的GH4720Li铸锭高温压缩变形时的力学流动行为,分析高温变形过程中微观组织演化规律。结果表明,GH4720Li合金在1100℃/0.1s-1条件下应力水平达到250MPa,且应力对热变形温度和应变速率敏感,动态再结晶是主要的软化机制。粗晶组织提高了合金动态再结晶临界变形温度和应变速率,如在变形量为60%,变形条件为1140℃/0.001s-1和1180℃/0.001s-1才能发生完全动态再结晶。计算的粗晶GH4720Li合金热变形激活能Q=1171kJ/mol,较高的热变形激活能表明粗晶组织不利于热塑性变形和动态再结晶的发生。基于本文研究,铸态GH4720Li合金开坯温度应高于1140℃,同时保证较低的应变速率,以确保动态再结晶的充分发生,实现枝晶组织破碎。

    Abstract:

    To study the fogging of GH4720Li nickel-based superalloy sufficiently, the hot deformation of the homogenization heat treated GH4720Li was carried out on Gleeble-3800 hot simulation experiment machine, and the microstructure evolution during high temperature deformation was also analyzed. Results show that the flow stress of GH4720Li at 1100℃/0.1s-1 is about 250MPa hich is sensitive to the deformation temperature and strain rate, also dynamic recrystallization is the main softening mechanism. Coarse grain improves the critical deformation temperature and strain rate for dynamic recrystallization, and complete dynamic recrystallization is obtained at 1140~1180℃ under strain rate of 0.001 s-1. The thermal deformation activation energy is calculated as Q= 1171 kJ/mol, and the higher thermal deformation activation indicates that the coarse grain is detrimental to hot workability and dynamic recrystallization for GH4720Li alloy. It is reveals that forging temperature for coarse GH4720Li alloy is determined above 1140℃, and low stran rate is necessary to ensure the occurance of dynamic recrystallization and dendrite broken.

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马腾飞,杜刚,齐锐,周宣,李宇力,张于胜,张平祥.粗晶U720Li合金热变形行为与动态再结晶特点[J].稀有金属材料与工程,2020,49(1):201~208.[matengfei, dugang, qirui, zhouxuan, liyuli, zhangyusheng, zhangpingxiang. Deformation behavior and dynamic recrystallization characteristic of a coarse U720Li alloy[J]. Rare Metal Materials and Engineering,2020,49(1):201~208.]
DOI:10.12442/j. issn.1002-185X.20181233

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  • 收稿日期:2018-12-09
  • 最后修改日期:2019-01-14
  • 录用日期:2019-02-21
  • 在线发布日期: 2020-02-16
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