(1. 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(diǎn)實(shí)驗(yàn)室，北京 100083；
2. 東北輕合金有限責(zé)任公司，哈爾濱150060)
摘 要: 粗晶環(huán)是中高強(qiáng)度鋁合金擠壓型材常見(jiàn)的組織缺陷之一，揭示鋁合金型材的粗晶環(huán)形成規(guī)律對(duì)于制定合理的擠壓和熱處理制度、進(jìn)而抑制粗晶環(huán)的形成具有重要意義。以7136鋁合金擠壓型材試樣為對(duì)象，研究不同固溶條件下試樣的粗晶環(huán)形成規(guī)律，并從再結(jié)晶組織和析出相形貌分布特征等方面分析粗晶環(huán)的形成原因。結(jié)果表明：試樣的粗晶環(huán)形成最低溫度為450 ℃，且隨固溶溫度的提高，粗晶環(huán)深度逐漸增大；固溶溫度470 ℃保溫30 min時(shí)粗晶環(huán)的深度為63 mm。在固溶溫度470 ℃下時(shí)，隨著保溫時(shí)間的延長(zhǎng)，粗晶環(huán)的深度開始增加較快，然后逐漸減慢，60 min后，繼續(xù)延長(zhǎng)保溫時(shí)間粗晶環(huán)深度基本不變。在擠壓過(guò)程中，試樣邊部再結(jié)晶程度約為心部的兩倍，同時(shí)，由于邊部基體Mg、Zn貧化導(dǎo)致析出h相(MgZn2)較少，對(duì)晶粒長(zhǎng)大的抑制作用較弱，因此，擠壓試樣在固溶過(guò)程中易形成粗晶環(huán)。
關(guān)鍵字: 7136鋁合金；粗晶環(huán)；擠壓；再結(jié)晶
（1. Key Laboratory for Advanced Materials Processing, Ministry of Education, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China;
2. Northeast Light Alloy Co., Ltd., Harbin 150060, China）
Abstract:The peripheral coarse grain(PCG) is one of the common microstructure defects of middle and high strength aluminium alloy extruded profiles. It is important to reveal the formation rule of PCG in aluminium alloy extruded profiles for making reasonable extrusion and heat treatment process and then inhibiting the formation of PCG. The formation of PCG in 7136 aluminum alloy extruded profiles under different solid solution conditions was studied, and the reasons for the formation of PCG was analyzed from the aspects of recrystallization structure and morphology distribution of precipitated phases. The results show that the lowest temperature for the formation of PCG is 450 ℃, and the depth of PCG increases with increasing solution temperature. The depth of PCG at 470 ℃ for 30 min is 63 mm. At 470 ℃ solution temperature, the depth of PCG increases rapidly with the prolongation of holding time, then increases slowly, and continues to prolong the holding time after 60 min, the depth of PCG is basically unchanged. In the extrusion process, the recrystallization degree at the edge of the specimen is about twice as much as that at the core. At the same time, due to the depletion of Mg and Zn at the edge of the specimen, the precipitation of MgZn2 is less and the inhibition of grain growth is weaker, so, the PCG is easy to be formed in the solid solution process of extruded specimen.
Key words: 7136 aluminum alloy; peripheral coarse grain; extrusion forming; recrystallization
