Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第18卷    第8期    总第113期    2008年8月

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文章编号:1004-0609(2008)08-1432-08
Al-Zn-Mg-Cu-Cr合金厚板组织细化
林高用,杨 伟,孙利平,彭大暑

(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6 mm以上的Al-Zn-Mg-Cu-Cr合金再结晶晶粒组织和第二相结构深度细化:短横向平均晶粒尺寸为8 μm,纵向及长横向平均晶粒尺寸为12 μm,第二相点状颗粒尺寸一般小于3 μmITMT工艺细化晶粒的机理主要是利用变形储能和第二相的有利影响,通过不连续再结晶实现组织细化。

 

关键词: Al-Zn-Mg-Cu-Cr合金;厚板;ITMT工艺;不连续再结晶;组织细化

Structures refinement of Al-Zn-Mg-Cu-Cr alloy thick plates
LIN Gao-yong, YANG Wei, SUN Li-ping, PENG Da-shu

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

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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