COMPOSITION OF STEEL FOR PRODUCTION OF COLD ROLLED ITEMS OUT OF POLYPHASE STEEL Russian patent published in 2008 - IPC C22C38/06 C22C38/14 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention refers to a steel composition to be used in a method of production of cold rolled items out of TRIP-steel without coating or processed by a method of electrolyte or hot zinc-plating. To achieve high ultimate tensile strength in combination with a big elongation and improvement of welding characteristics there produced steel containing mas.portions: carbon 1300-2600, manganese 10000-22000, aluminium 8000-15000, silicon 2000-6000, phosphorus 400-1000, sulphur not more, than 120, nitrogen not more, than 200, titanium not more, than 1000, niobium not more, than 1000, vanadium not more, than 1000, boron not more, than 10, iron and insignificant impurities - the rest. The method of production of a cold rolled item out of TRIP-steel includes producing a steel slab, hot rolling of the slab, the final temperature of which is higher, than the temperature of completed creation of austenite "Асз", thus a hot rolled item is produced which is further cooled to a temperature of winding into a roll between 500°C and 680°C, then it is wound into a roll at a specified temperature, then the item is etched to eliminate oxides, then it is cold rolled to decrease thickness with minimum pressing of 40%.

EFFECT: producing steel of high ultimate strength.

19 cl, 3 ex, 8 tbl