In an attempt to refine the grain structure of 200mm wide sheets of 7475 based aluminum alloy containing Zr, a new warm rolling method under the control of both roll temperature and material temperature was used. The warm rolled sheets as solution-heat treated had subgrain structure through the thickness with a high proportion of low angle boundary less than 15 deg. The average subgrain diameter was approximately 3 mum. The strength of the warm rolled sheet in T6 condition was about 10 percent higher than that of a conventional 7475 alloy sheet produced by cold rolling. As the most remarkable point, a high Lankford value (plastic strain ratio of width to thickness) of 3.5 was observed in the orientation of 45 deg to the rolling direction, with the average Lankford value of 2.2. It was thought that the high Lankford value should be derived from well developed beta -fiber, especially the strong {011} brass component. The warm rolled sheet also had good resistance to SCC. From Kikuchi lines analysis and TEM images, it was found that PFZ was hardly formed along the low angle boundaries of the warm rolled sheet in T6 condition. This should be a factor to lead good resistance to SCC because of reducing the difference in electrochemical property between the grain boundary area and the grain matrix.
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