(1. 哈尔滨工业大学 金属精密热加工国防科技重点实验室，哈尔滨 150001；
2. 哈尔滨工业大学 材料科学与工程学院，哈尔滨 150001)
摘 要: 为解决大尺寸铝合金薄壁构件室温成形易开裂、热成形组织性能损伤的难题，基于铝合金超低温变形伸长率和硬化指数提高的“双增效应”，提出了铝合金超低温成形新原理；分析了变形温度、合金种类、热处理状态、晶粒尺寸对铝合金低温力学性能的影响规律，研究了铝合金在超低温下的宏观塑性变形行为，表征了低温变形诱发的滑移行为、微观应变、位错形态和断口形貌，获得了超低温下的极限胀形高度、极限拉深比、极限扩孔率和成形极限图，阐明了超低温复杂应力下铝合金成形性能显著提高的宏微观变形机理。超低温成形新原理为实现铝合金复杂形状构件成形提供了理论依据和新工艺方法。
关键字: 铝合金；薄壁构件；超低温成形；双增效应；成形性能
（1. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 1500011, China;
2. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China）
Abstract:In order to avoid cracking in cold forming and mechanical property damage in hot forming of aluminum alloy sheet, a novel forming principle was proposed to deform large-size curved aluminum alloy shells at cryogenic temperatures based on the dual enhancement effect regarding on elongation and hardening was proposed during cryogenic deformations of aluminum alloy. The effects of deformation temperature, alloy type, heat-treatment state and grain size were analyzed on the mechanical properties of aluminum alloy. The deformation behaviors of aluminum alloy were investigated in a cryogenic environment. The micro-deformation behavior was clarified via slip behavior, micro strain, dislocations and fracture morphology at cryogenic temperatures. The limit bulging height, limit drawing ratio, limit hole expanding rate and forming limit diagram are obtained, respectively. It is shown that the formability of aluminum alloys is significantly improved under complex stress states at ultra-low temperature, and complex components can be fabricated at cryogenic temperatures.
Key words: aluminum alloy; thin-wall components; cryogenic forming; dual enhancement effect; formability
