(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083； 2. 中南大學(xué) 輕合金研究院，長沙 410083; 3. 江蘇豪然噴射成形合金有限公司，鎮(zhèn)江 212004)
摘 要: 通過高溫?zé)釅嚎s實(shí)驗(yàn)研究噴射成形7055鋁合金的熱變形行為，實(shí)驗(yàn)溫度為340~480 ℃，應(yīng)變速率為0.001~1 s-1。結(jié)果表明：該合金在變形過程中的流變應(yīng)力隨著溫度升高和應(yīng)變速率的降低而降低，在480 ℃時(shí)會(huì)出現(xiàn)失穩(wěn)現(xiàn)象。變形過程中的主要軟化機(jī)制為動(dòng)態(tài)回復(fù)和動(dòng)態(tài)再結(jié)晶，其中低溫時(shí)，動(dòng)態(tài)回復(fù)占主導(dǎo)地位，隨著溫度升高，軟化機(jī)制逐步轉(zhuǎn)變?yōu)閯?dòng)態(tài)再結(jié)晶，再結(jié)晶晶粒的尺寸隨著溫度的升高而增大。基于動(dòng)態(tài)材料模型和極化互惠模型，結(jié)合熱變形中的組織演變，確定該合金在應(yīng)變量為0.7時(shí)的適宜加工范圍為：溫度范圍400~420 ℃，應(yīng)變速率0.01~0.1 s-1，此時(shí)對(duì)應(yīng)的動(dòng)態(tài)材料模型加工圖能量耗散效率超過33%，極化互惠模型加工圖內(nèi)在加工參數(shù)在65%~70%之間。
關(guān)鍵字: 噴射成形7055鋁合金；加工圖；動(dòng)態(tài)材料模型；極化互惠模型
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China; 2. School of Light Alloys Research Institution, Central South University, Changsha 410083, China; 3. Hao-ran Co. Ltd., Jiangsu, Zhenjiang 212004, China）
Abstract:The hot deformation behavior of spray formed 7055 aluminum alloy was studied by a series of isothermal compression tests at different temperatures ranging from 340 ℃ to 480 ℃ and strain rates varying from 0.001 s-1 to 1 s-1. The results show that the flow stress decreases with increasing temperature and deceasing strain rate, and the instable behaviors occurs at 480 ℃. The main softening mechanisms are dynamic recovery and dynamic recrystallization. The dynamic recovery occurs at low temperature and it turns to dynamic recrystallization as temperature increases. The grain size increases with increasing temperature. Based on dynamic materials model, polar reciprocity model and microstructure evolution, the appropriate processing conditions for this alloy are in the strain rate range of 0.01–0.1 s-1 and deformation temperature range of 400–420 ℃, with power efficiency over 33% and intrinsic workability parameter of 65%–70%, respectively.
Key words: spray formed 7055 aluminum alloy; processing map; dynamic materials model; polar reciprocity model
