① O = annealed ;
② H = work hardened;
③ T6 = solution heat treated + artificial aged;
④ T1 = high temperature molding + natural aged;
⑤ T3 = after solution heat treated, cold processing, and then natural aged to a basically stable;
⑥ T4 = after solution heat treated, natural aged to a basically stable;
⑦ T5 = cooled by high temperature molding, and then artificially aged to a basically stable;
⑧ T7 = after solution heat treated, overaged;
⑨ T8 = after solution heat treated, cold processing , and then artificial aged
◎ d = round rod diameter or thickness of square rod or hexagonal rod, t = square rod or hexagonal rod thickness, unit mm