(1. 哈爾濱工業(yè)大學(xué) 金屬精密熱加工國防科技重點實驗室，哈爾濱 150001；
2. 哈爾濱工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，哈爾濱 150001)
摘 要: 為解決大尺寸鋁合金薄壁構(gòu)件室溫成形易開裂、熱成形組織性能損傷的難題，基于鋁合金超低溫變形伸長率和硬化指數(shù)提高的“雙增效應(yīng)”，提出了鋁合金超低溫成形新原理；分析了變形溫度、合金種類、熱處理狀態(tài)、晶粒尺寸對鋁合金低溫力學(xué)性能的影響規(guī)律，研究了鋁合金在超低溫下的宏觀塑性變形行為，表征了低溫變形誘發(fā)的滑移行為、微觀應(yīng)變、位錯形態(tài)和斷口形貌，獲得了超低溫下的極限脹形高度、極限拉深比、極限擴孔率和成形極限圖，闡明了超低溫復(fù)雜應(yīng)力下鋁合金成形性能顯著提高的宏微觀變形機理。超低溫成形新原理為實現(xiàn)鋁合金復(fù)雜形狀構(gòu)件成形提供了理論依據(jù)和新工藝方法。
關(guān)鍵字: 鋁合金；薄壁構(gòu)件；超低溫成形；雙增效應(yīng)；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
