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保温时间对难变形高温合金U720Li热变形行为的影响
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1.沈阳工业大学材料科学与工程学院;2.辽宁科技大学;3.中国科学院金属研究所

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国家自然科学基金项目(面上项目,重点项目,重大项目)(52174317、51904146)


Influence of Holding Time on the Hot Deformation Behavior of Hard-Deformed Superalloy U720Li
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The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) (grant numbers 52174317 and 51904146)

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    摘要:

    为了改善难变形高温合金U720Li的热加工性能,研究了变形前保温时间(5 min、10 min)对该合金的热变形行为的影响。结果表明,流动应力随应变速率的提高而增大,但随变形温度和保温时间的增加而减小。依据所建立的Arrhenius本构模型计算的峰值应力与实验值吻合良好,说明该模型可准确预测U720Li合金热变形行为。保温时间为5 min和10 min的热变形激活能分别为992.006 kJ·mol-1和850.996 kJ·mol-1。建立了U720Li合金在这两种保温时间下的热加工图。通过分析热加工图各区域对应的变形组织,明确了保温5 min的最佳热加工条件为1090~1110 ℃/1~10 s-1和1146~1180 ℃/1~10 s-1,而保温10 min的为1080~1090 ℃/1~10 s-1和1153~1160 ℃/1~10 s-1。可见适当缩短变形前保温时间可扩大该合金的安全加工窗口。在未发生开裂的情况下,动态再结晶(DRX)晶粒随变形温度和保温时间的增加而逐渐增大,但随应变速率的增加先减小后增大。当变形温度低于1100 ℃,主要DRX机制为颗粒诱导连续动态再结晶(PI-CDRX)。当变形温度高于1130 ℃,主要DRX机制转变为不连续动态再结晶(DDRX)。

    Abstract:

    To improve the hot workability of hard-deformed superalloy U720Li, the effect of holding time before deformation (5 min and 10 min) on its hot deformation behavior was investigated using hot compression tests. The flow stress increases with increase of strain rate, while decreases with increase of deformation temperature and holding time. Based on the obtained Arrhenius-type constitutive models, the calculated peak stresses are in good agreement with experimental values, and the deformation activation energies for the holding time of 5 min and 10 min were calculated to be 992.006 kJ·mol-1 and 850.996 kJ·mol-1, respectively. Moreover, processing maps of U720Li alloy at these two holding time were constructed. Through observation of deformation microstructures in each domain of the processing maps, the optimal hot working conditions for the holding time of 5 min were determined to be 1090~1110 ℃/1~10 s-1 and 1146~1180 ℃/1~10 s-1, while those for the holding time of 10 min were 1080~1090 ℃/1~10 s-1 and 1153~1160 ℃/1~10 s-1. This indicates that the “safe” processing window can be obviously enlarged by shortening the holding time reasonably. In the absence of cracking, the dynamic recrystallization (DRX) grain size increases gradually with increasing deformation temperature and holding time, but it first decreases and then increases with the increase of strain rate. When the deformation temperature is below 1100 °C, the DRX mechanism is mainly the particle-induced continuous dynamic recrystallization (PI-CDRX). But as the temperature was raised to above 1130 °C, the main DRX mechanism changes to discontinuous dynamic recrystallization (DDRX).

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臧喜民,赵广迪,武金江,姜昊源,姚晓雨.保温时间对难变形高温合金U720Li热变形行为的影响[J].稀有金属材料与工程,,().[Zang Ximin, Zhao Guangdi, Wu Jinjiang, Jiang Haoyuan, Yao Xiaoyu. Influence of Holding Time on the Hot Deformation Behavior of Hard-Deformed Superalloy U720Li[J]. Rare Metal Materials and Engineering,,().]
DOI:10.12442/j. issn.1002-185X.20230790

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历史
  • 收稿日期:2023-12-05
  • 最后修改日期:2024-01-24
  • 录用日期:2024-02-01
  • 在线发布日期: 2024-03-22
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