Abstract
In order to clarify the crack morpholoy in 180° bend-forming of Ti films deposited on (011) [100] single crystal of silicon steel and ferritic stainless steel sheets, Ti coating by the hollow cathode discharge (HCD) method was done on polished single crystal and stainless steel sheets, and then the Ti-coated samples were cutted to (A) rolling direction and (B) perpendicullar to the rolling direction, and 180° bend-formed, and observed by the scanning electron microscope.
(A) Ti-coated silicon steel of (011) [100] single crystal sample showed no distictive crack in Ti films on steel sheet, on which slip lines at intervals of 210 μm to the [1210] Ti direction could be observed in a rectangular-like morphology 1025 μm in width and 2080 μm in length.
Moreover, many fine slip lines at intervals of 50-200 nm to the [0001] Ti direction could be observed.
(B) Ti-coated silicon steel of (011) [100] single crystal sample also showed no distictive crack in Ti films on steel sheet, on which slip lines at intervals of 210 μm to the [0001]Ti direction could be observed in a rectangular-like morphology 1040 μm in width and 2070 μm in length.
Moreover, many fine slip lines at intervals of 200-500 nm to the [1210] Ti direction could be observed.
In contrast, Ti-coated stainless sheel sheet sample showed many highly-curved cracks of 1050 μm length in a slightly elongated state.
It should be noted that the crack morphology of Ti films of single crystal samples of silicon steel differed remarkably depending on (A) rolling direction and (B) perpendicullar to the rolling direction, and was caused by good coherency to only a axis of [1210] Ti and [100] Fe.
