METHOD FOR PRODUCING COLD-ROLLED HOT-GALVANIZED FLAT PRODUCTS FROM STEEL WITH TWO-PHASE FERRITE-MARTENSITE STRUCTURE Russian patent published in 2021 - IPC C21D9/46 C21D8/02 C22C38/26 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and in particular to a method for the production of cold-rolled, hot-dip galvanized high-strength flat products from steel with a two-phase ferrite-martensitic structure, which can be used in the automotive industry. The slab undergoes hot rolling, followed by water cooling and coiling of the strip. Then, pickling and cold rolling are carried out, after which the strip is processed in a continuous hot-dip galvanizing unit by heating to the annealing temperature, holding, accelerated cooling, applying a zinc coating and tempering. The mentioned slab is obtained from steel having the following chemical composition, wt. %: carbon - 0.06-0.14, silicon - no more than 0.35, manganese - 1.3-2.6, chromium - 0.20-0.60, molybdenum - no more than 0.30, aluminum - 0.02-0, 08, niobium - no more than 0.08, phosphorus - no more than 0.02, sulfur - no more than 0.02, iron and inevitable impurities - the rest. The strip is heated to an annealing temperature of 730-800°C, accelerated cooling is carried out at a rate of 20-35°C / s and finished at a temperature of 450-500°C, and tempering is carried out with an elongation of 0.3-0.7%. In addition, hot rolling is finished at a temperature of 780-890°C, the strip is coiled into a coil at a temperature of at least 560°C, and the specific tension of the strip in a continuous hot-dip galvanizing unit at the stages of heating, holding, cooling and applying a zinc coating is at least 0.4 kg / mm².

EFFECT: stable increase in ductility and reduction in production costs for cold-rolled hot-dip galvanized flat products from a two-phase steel with a ferrite-martensitic structure, while maintaining a set of mechanical properties.

3 cl, 2 tbl, 1 ex