內層組織的影響
(華南理工大學 機械與汽車工程學院，金屬新材料制備與成形廣東省重點實驗室，廣州 510640)
摘 要: 為了控制梯度復合鑄錠橫截面上的內層組織分布，通過改變內熔體澆口在結晶器中心線上的不同位置，采用雙流澆注半連續(xù)鑄造技術制備內層合金寬度不同的7075/6009梯度復合鑄錠，分析不同內層合金寬度的鑄錠橫截面上的宏觀組織、硬度分布及其微觀組織的二次枝晶間距，探討內熔體澆口位置對雙流澆注半連續(xù)鑄造技術的內熔體形成液穴的影響。結果表明：隨著內熔體澆口探入結晶器深度的加大，鑄錠橫截面的內層合金組織的寬度逐漸加大，洛氏硬度始降點逐漸外移，鑄錠橫截面的Zn含量始降點也逐漸外移，半徑為10 mm處的二次枝晶間距逐漸縮小。
關鍵字: 連續(xù)鑄造；7075/6009鋁合金；導管位置；凝固液穴
composition and structures of 7075/6009 Al alloy ingots
（Guangdong Key Laboratory for Advanced Metallic Materials Processing, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China）
Abstract:In order to control the distribution of internal layer on the cross section of the gradient composite ingots, several 7075/6009 composite ingots were prepared by double-stream-pouring continuous casting by adjusting the positions of submerged entry nozzle in the mould. Macrostructures, hardness distributions and secondary dendrite spacing of the prepared ingots with different internal layer thicknesses were investigated. The effect of the position of submerged entry nozzle in the mould on liquid pool of inside melt was analyzed. The results show that, with the increase of the depth of submerged entry nozzle in the mould, the thickness of internal layer on the cross section of the ingots increases gradually, and the initial dropping points of Rockwell hardness and Zn content move to the ingot surface. Furthermore, the secondary dendrite spacing of the alloy at the radius of 10 mm decreases.
Key words: continuous casting; 7075/6009 Al alloy; entry nozzle position; solidification liquid pool
