(1.中南工業(yè)大學材料科學與工程系，長沙410083；
2.西南鋁加工廠，重慶631326)
摘 要: 通過微觀組織分析，研究了LY12擠壓棒材在固溶處理前進行足夠的冷拔變形可消除其粗晶環(huán)的現象。足夠的冷變形增加了再結晶的形核率，改變了第二相粒子、殘余應力的大小和分布，從而獲得了均勻的細晶組織，消除了粗晶環(huán)。由此還分析了LY12CZ擠壓棒粗晶環(huán)形成的原因，即擠壓過程中棒材邊部劇烈的剪切變形使其具有很大的畸變能，促使第二相粒子聚集長大而失去對再結晶的抑制作用，在隨后的淬火加熱過程中發(fā)生一次再結晶而聚集長大形成粗晶環(huán)。
關鍵字: LY12鋁合金 粗晶環(huán) 冷拉拔
COARSE-GRAIN RECRYSTALLIZATION ANNULUS OF
EXTRUDED BARS OF LY12CZ ALUMINIUM ALLOY
（1．Department of Materials Science and Engineering,
Central South University of Technology, Changsha 410083
2.Southwestern Aluminium Fabrication Plant, Chongqing631326）
Abstract:It has been studied by analyzing the microstructure that the coarse-grain recrystallization annulus in directly extruded LY12 aluminium alloy bars can be eliminated by sufficient cold drawing reduction before solid solution. The nucleation of recrystallization increases by certain cold drawing reduction.Cold drawing results in more homogeneous distribution of residual stress so that the elimination of coarse grain annulus and homogeneous fine grain structure can be achieved.The mechanism of the formation of the annulus in LY12CZ bars was discussed as well.It is concluded that the formation of the annulus can be essentially attributed to the violent shear deformation during hot extruding. Large shear strain brings large distortion energy to the outer layer of the products, thus facilitating the gathering of the particles containing manganese, and making them lose the retardation to recrystallization grain growth. Consequently, the nuclei formed by subgrain coalescence grow up accumulatively to form coarse recrystallization annulus during subsequent reheating and soaking processes before quenching.
Key words: LY12 aluminium alloy coarse-grain recrystallization annulus cold drawing
