(1. 北京科技大學(xué)新材料技術(shù)研究院現(xiàn)代交通金屬材料與加工技術(shù)北京實驗室，北京 100083；
2. 北京科技大學(xué)新材料技術(shù)研究院材料先進(jìn)制備技術(shù)教育部重點實驗室，北京 100083)
摘 要: 由于鍛造2014鋁合金大型鍛件常采用大尺寸擠壓棒材為坯料，闡明擠壓棒材心部和表層組織差異對變形行為和再結(jié)晶組織的影響，對于鍛造工藝參數(shù)制定、鍛造過程和鍛件組織性能的精確控制具有重要意義。本文在溫度為250~450 ℃和應(yīng)變速率為0.001~1 s-1的條件下研究了心部和邊部試樣的熱變形行為。結(jié)果表明：心部和邊部試樣在不同變形條件下的流變應(yīng)力均無明顯差異，但再結(jié)晶和位錯演化行為存在明顯差別。兩種試樣的主要動態(tài)再結(jié)晶機(jī)制是不連續(xù)動態(tài)再結(jié)晶，此外，心部試樣還存在幾何動態(tài)再結(jié)晶，邊部試樣還存在連續(xù)動態(tài)再結(jié)晶。在400~450 ℃變形時，隨應(yīng)變速率降低，邊部試樣的位錯密度顯著降低，而心部試樣的位錯密度變化較小。綜合考慮熱加工圖和變形后組織的均勻性，實際鍛造時較為合適的工藝條件是：將變形溫度控制在400~450 ℃，心部應(yīng)變速率控制在0.01~0.1 s-1，邊部應(yīng)變速率控制在0.1~1 s-1。
關(guān)鍵字: 2014鋁合金；熱變形；組織不均勻；動態(tài)再結(jié)晶；位錯組態(tài)
（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
