Abstract: A rotation support device of a swivel seat is provided, which not only obtains a stable bending rigidity even at a rotation position at any angle among the entire rotating section of a seat, but also maintains a constant rotation speed over the entire range of the rotating section by guiding and buffering functions of a sliding friction member, thereby providing more excellent operation sensibility. The rotation support device includes: a fixed frame which is installed on a body of a vehicle; a rotating frame which is rotatably installed with respect to the fixed frame; and a rotating sliding portion which is installed to be able to contact an area of an entire section of a rotation direction of the rotating frame with respect to the fixed frame in such a contacting manner that a buffer function is continuous. The rotating sliding portion includes sliding friction members.

Abstract: Provided is a high manganese nitrogen-containing steel sheet. The high manganese nitrogen-containing steel sheet according to the present invention comprises 0.5 to 1.0 wt % of carbon, 10 to 20 wt % of manganese, 0.02 to 0.3 wt % of nitrogen, with a remainder of Fe and unavoidable impurities. The high manganese nitrogen-containing steel sheet according to the present invention produces an austenite phase at room temperature, in which the stacking fault energy is effectively controlled by adding chrome and nitrogen. Accordingly, the high manganese nitrogen-containing steel sheet of the present invention produces a mechanical twin during the plastic deformation of the steel sheet, thereby increasing the work hardening rate, tensile strength, and workability.