(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 廣東和勝工業(yè)鋁材股份有限公司，中山 528463)
摘 要: 采用熱壓縮試驗、光學(xué)顯微鏡和透射電子顯微鏡研究熱變形參數(shù)對Al-Zn-Mg-Cu鋁合金淬火敏感性的影響。結(jié)果表明：隨Z參數(shù)值增加，硬度先增加后減小，再結(jié)晶程度和淬火敏感性則先減小后增加，在lnZ為28.44~ 28.62的范圍內(nèi)，室溫水淬硬度值最大，為188.8HV，而再結(jié)晶分數(shù)最小，為3.5%，空氣淬火較室溫水淬火硬度下降率最小，為2.5%。根據(jù)Z參數(shù)值范圍確定淬火敏感性最小區(qū)間對應(yīng)的熱變形加工制度為變形溫度387~434 ℃、變形速率0.23~1.23 s-1，變形溫度443~450 ℃、變形速率0.61~1.77 s-1。淬火敏感性是由于微觀組織中的Al3Zr粒子、晶界及亞晶界析出粗大η相導(dǎo)致過飽和固溶體溶度降低所致。不同的熱變形制度會導(dǎo)致組織中Al3Zr粒子相界、晶界及亞晶界含量不同。當(dāng)三者協(xié)同影響最小時，合金具有最小的淬火敏感性。隨著Z參數(shù)值增加，Al3Zr粒子尺寸及與基體的錯配度與再結(jié)晶程度趨勢相同，尺寸與錯配度越小析出粗大η相尺寸越小，面積分數(shù)越低。
關(guān)鍵字: Al-Zn-Mg-Cu鋁合金；Z參數(shù)；淬火敏感性；淬火析出相
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China？
2. Guangdong Hoshion Industrial Aluminium Co.,Ltd., Zhongshan 528463, China）
Abstract:The effects of hot deformation parameters on the quenching sensitivity of Al-Zn-Mg-Cu aluminum alloy were studied by hot compression test, OM and TEM. The results show that, when Z-parameter increases, the hardness increases firstly and then decreases, while the degree of recrystallization and quenching sensitivity decrease firstly and then increase. The hardness of RT water quenching is the highest (188.8HV). The recrystallization fraction is the smallest (3.5%), when lnZ ranges from 28.44 to 28.62, at the same time, the decline of minimum hardness after air quenching reaches 2.5% comparing with that of RT water quenching. According to the Z parameter, it can be determined that the corresponding thermal deformation institution to the minimum zone of quenching sensitivity are temperature 387-434 ℃, deformation rate 0.23-1.23 s-1 and temperature 443-450 ℃, deformation rate 0.61-1.77 s-1. The auenching sensitivity is caused by micro particles as Al3Zr, the coarse η phase precipitates on grain boundary and subgrain boundaries, leading to solubility of supersaturated solid solution decreasing. Different thermal deformation institution will result in different Al3Zr phase boundaries, grain boundaries and sub-grain boundaries. The less the synergy effect is, the better the quenching sensitivity is. With the Z-parameter increases, the grain size of Al3Zr particles and the mismatch of that with the matrix show the same tendency with the recrystallization degree, the lower the grain size and mismatch are, the smaller the area fraction of recrystallization is.
Key words: Al-Zn-Mg-Cu aluminum alloy; Z-parameter; quenching sensitivity; quenching precipitation
