(中南大學(xué) 材料科學(xué)與工程學(xué)院 教育部有色金屬材料科學(xué)與工程重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要:
提出一種細(xì)化Al-Zn-Mg-Cu-Cr合金厚板組織的“強(qiáng)化固溶→過(guò)時(shí)效→中溫多向鍛造→中溫軋制→快速加熱再結(jié)晶處理”的中間變形熱處理(ITMT)技術(shù)原型，采用金相分析、能譜分析和透射電鏡分析等方法，研究ITMT工藝過(guò)程中的組織演變規(guī)律和晶粒細(xì)化的機(jī)理，并討論利用不連續(xù)再結(jié)晶控制晶粒大小所具備的條件。結(jié)果表明：采用ITMT工藝能夠保證Al-Zn-Mg-Cu-Cr合金厚板的充分、均勻變形，在軋制變形量不超過(guò)80%的條件下，使厚度達(dá)
關(guān)鍵字: Al-Zn-Mg-Cu-Cr合金；厚板；ITMT工藝；不連續(xù)再結(jié)晶；組織細(xì)化
（The Key Laboratory of Nonferrous Metals Materials Science and Engineering, Ministry of Education, School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:An intermediate thermal-mechanical treatment (ITMT), which includes reinforced solid solution, over-aging, heavy strain by combination of multi-directional forging and rolling at warm temperature and re-crystallization by fast heating was proposed and studied for structure refining of Al-Zn-Mg-Cu-Cr alloy thick plates. The structures evolution laws and the mechanism of grain refining with the above ITMT were studied by means of OM, EDS and TEM. Then the qualifications of controlling the grain size under discontinuous re-crystallization were discussed. The results show that ITMT process can make Al-Zn-Mg-Cu-Cr alloy thick plates deform sufficiently and equally, also make the structure of re-crystallization refine effectively, though the rolling reduction is not more than 80%. The average re-crystallization grain size is refined to around 8 μm in the short transverse direction and 12 μm in the vertical or long transverse direction. Most of the secondary particles are refined to less than 3 μm. The mechanism of grain refining for ITMT can be summarized as: the fine, homogenous and equal-axial grains are refined by discontinuous re-crystallization, making full use of the heavy strain energy formed by the severe plastic deformation and the feasible size and distribution of secondary particles formed chiefly in the over-aging.
Key words: Al-Zn-Mg-Cu-Cr alloy; thick plates; intermediate thermal-mechanical treatment (ITMT); discontinuous re-crystallization; structure refinement
