(中南大学 材料科学与工程学院 教育部有色金属材料科学与工程重点实验室，长沙 410083)
摘 要:
提出一种细化Al-Zn-Mg-Cu-Cr合金厚板组织的“强化固溶→过时效→中温多向锻造→中温轧制→快速加热再结晶处理”的中间变形热处理(ITMT)技术原型，采用金相分析、能谱分析和透射电镜分析等方法，研究ITMT工艺过程中的组织演变规律和晶粒细化的机理，并讨论利用不连续再结晶控制晶粒大小所具备的条件。结果表明：采用ITMT工艺能够保证Al-Zn-Mg-Cu-Cr合金厚板的充分、均匀变形，在轧制变形量不超过80%的条件下，使厚度达
关键字: Al-Zn-Mg-Cu-Cr合金；厚板；ITMT工艺；不连续再结晶；组织细化
（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
