A series of compressive tests of virgin specimens and ones corrected by heating was carried out. Buckling strength of specimens by heating correction became lower than that of virgin specimens. The ultimate strength of them was almost equal to that of virgin specimens. Residual imperfection, which was not completely corrected by heating, largely affects a decreasing of buckling strength. Making residual imperfection extremely small, buckling strength was hardly lowered. If the absolute value of residual imperfection was same as plate thickness, 80-9O% buckling strength of a virgin specimen could be kept.
