(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)教育部重點實驗室，北京 100083；
2. 中鋁材料應(yīng)用研究院有限公司，北京 102209)
摘 要: 熱冷組合鑄型(Heating-cooling combined mold, HCCM)水平連鑄是一種制備高精度管坯的短流程新技術(shù)。本文采用HCCM水平連鑄成功制備出d 70 mm×6 mm規(guī)格的5A02鋁合金管坯，研究了微觀組織對管坯力學(xué)性能的影響。結(jié)果表明：不同的連鑄工藝導(dǎo)致形成了三種不同的鑄態(tài)組織，分別為粗大等軸晶組織、粗大柱狀晶組織和細(xì)長柱狀晶組織。更較大的連鑄速度和溫度梯度導(dǎo)致形成的細(xì)長柱狀晶組織表現(xiàn)出優(yōu)異的力學(xué)性能，其室溫抗拉強度為198 MPa，斷后伸長率為26.3%。在細(xì)長柱狀晶組織中，彌散分布的細(xì)小第二相和沿軸向的細(xì)長晶粒，以及Mg元素在α(Al)基體中的均勻分布使得管坯力學(xué)性能明顯提高。
關(guān)鍵字: 5A02鋁合金；HCCM連鑄；微觀組織；力學(xué)性能；第二相
（1. Key Laboratory for Advanced Materials Processing(MOE), Institute for Advanced Materials and Technology, University of Science and Technology Beijing. Beijing 100083, China;
2. Chinalco Materials Application Research Institute Co., Beijing 102209, China）
Abstract:Heating-cooling combined mold (HCCM) horizontal continuous casting was a new compact process technology for preparing tube billets with high precision. In this work, 5A02 aluminum alloy tube billets with 70 mm in diameter and 6 mm in wall thickness were fabricated by HCCM horizontal continuous casting, and the effect of microstructure on mechanical properties was investigated. The results show that the different HCCM processes result in three different microstructures, respectively coarse equiaxed grains, coarse columnar grains and slender columnar grains. The slender columnar grain introduced by the higher casting speed and temperature gradient presents the more excellent mechanical properties, including ultimate strength of 198MPa and elongation of 26.3%. The grain size, second phase size and the distribution of Mg element are main factors for mechanical properties. For the slender columnar grain, diffusion of fine second phase and the uniform distribution of Mg element in α(Al) matrix improve the mechanical properties of HCCM casted tube billets.
Key words: 5A02 aluminum alloy; horizontal continuous casting; microstructure, mechanical properties; second phase
