(1. 北京科技大学新材料技术研究院现代交通金属材料与加工技术北京实验室，北京 100083；
2. 北京科技大学新材料技术研究院材料先进制备技术教育部重点实验室，北京 100083)
摘 要: 由于锻造2014铝合金大型锻件常采用大尺寸挤压棒材为坯料，阐明挤压棒材心部和表层组织差异对变形行为和再结晶组织的影响，对于锻造工艺参数制定、锻造过程和锻件组织性能的精确控制具有重要意义。本文在温度为250~450 ℃和应变速率为0.001~1 s-1的条件下研究了心部和边部试样的热变形行为。结果表明：心部和边部试样在不同变形条件下的流变应力均无明显差异，但再结晶和位错演化行为存在明显差别。两种试样的主要动态再结晶机制是不连续动态再结晶，此外，心部试样还存在几何动态再结晶，边部试样还存在连续动态再结晶。在400~450 ℃变形时，随应变速率降低，边部试样的位错密度显著降低，而心部试样的位错密度变化较小。综合考虑热加工图和变形后组织的均匀性，实际锻造时较为合适的工艺条件是：将变形温度控制在400~450 ℃，心部应变速率控制在0.01~0.1 s-1，边部应变速率控制在0.1~1 s-1。
关键字: 2014铝合金；热变形；组织不均匀；动态再结晶；位错组态
（1. Beijing Laboratory of Metallic Materials and Processing for
Modern Transportation,University of Science and Technology Beijing, Beijing
100083, China;
2. Key Laboratory for Advanced Materials
Processing (MOE),University of Science and Technology Beijing, Beijing 100083,
China）
Abstract:The 2014 aluminum alloy large forgings are often forged with large-size extruded bars as blanks. To clarify the influence of the difference between the center and edge microstructures of the extruded bar on the deformation behavior and recrystallization microstructure is of great significance for the formulation of forging process parameters, the precise control of the forging process and the microstructure and properties of the forgings. In this paper, under the temperatures of 250-450 ℃ and strain rates of 0.001-1 s-1, the hot deformation behaviors of the center and edge samples were studied. The results show that there is no significant difference in the flow stress of the center and edge samples under different deformation conditions. However, there are obvious differences in the recrystallization behavior and dislocation evolution of the center and edge samples when they are deformed. In addition to discontinuous dynamic recrystallization in two samples, the geometric dynamic recrystallization also exists in the center sample and continuous dynamic recrystallization also exists in the edge sample. When deformed at 400-450 ℃, as the strain rate decreases, the dislocation density of the edge sample decreases significantly, while the dislocation density of the center sample changes less. Considering the hot processing map and the homogeneity of microstructure after deformation, it is more appropriate to control the deformation temperature at 400-450 ℃, the center strain rate at 0.01-0.1 s-1 and the edge strain rate at 0.1-1 s-1 during actual forging.
Key words: 2014 aluminum alloy; hot deformation; inhomogeneous microstructure; dynamic recrystallization; dislocation configuration
