極低炭素鋼板の再結晶集合組織に及ぼすMnとNの影響

Abstract

Additions of manganese and nitrogen have been investigated with respect to their effects on the development of recrystallization texture in very low carbon steels. Hot-rolled and decarburized steels with five different manganese contents (0.00 to 0.32 mass%) were individually adjusted to three levels of nitrogen (less than 2, 8 and 120 mass ppm) by atmosphere reactions and then cold-rolled 80% in reduction. These fifteen sheets were annealed up to 973 K with a very slow heating rate under appropriate atmospheres. Texture studies were carried out by X-ray diffraction method. Microstructures during recovery and recrystallization were also examined using the scanning electron microscope (back-sattered electron method) on the edge sections parallel to the rolling direction. Optimum textures for deep drawability were obtained with very low contents of manganese in solid solution (less than 0.04%) and intermediate levels of nitrogen (about 8 ppm). Steel chemistry apparently controls the final texture in both the cold rolling and annealing stage of processing. The cold rolling texture varies with manganese and nitrogen content. During recrystallization, nitrogen enhances the development of texture components with (111) parallel to the sheets.