High-strength steel material having outstanding ultra-low-temperature toughness and a production method therefor

The present invention relates to a steel material containing manganese and nickel which is used as a structural material for ultra-low-temperature storage containers for LNG (Liquefied Natural Gas) or the like, and relates to a production method therefor. More specifically, the object of the present invention is to provide: a steel material having high strength and also outstanding ultra-low-temperature toughness, because of the addition of the optimum proportion of inexpensive Mn or the like instead of expensive Ni, refinement of the structure through controlled rolling and cooling, and the precipitation of residual austenite by means of tempering; and a production method for the steel material. In order to achieve this object, the technical essence of the present invention comprises a production method for a steel material comprising: a heating step involving heating, in a temperature range of between 1,000 and 1,250 DEG C, a steel slab comprising, as percentages by weight, from 0.01 to 0.06% of carbon (C),