METHOD FOR PRODUCING PRESS-HARDENED PARTS WITH HIGH PRODUCTIVITY Russian patent published in 2022 - IPC C21D9/48 C21D6/00 C23C2/12 C23C2/28 C23C2/40 C23C8/14 C23C8/80 

FIELD: working of metal.

SUBSTANCE: group of inventions relates to a method for producing a steel roll, sheet or workpiece. The method includes the following consecutive stages: producing a pre-coated steel roll, sheet or workpiece, consisting of heat-treated steel substrate protected with a preliminary coating of aluminium or an aluminium alloy, wherein the pre-coating is directly formed as a result of the process of hot aluminising without additional heat treatment, wherein the pre-coating thickness is between 10 and 35 micrometers on each side of the steel roll, sheet or workpiece, then heating the steel roll, sheet or workpiece in a furnace in an atmosphere containing at least 5% oxygen to a temperature θ₁ ranging from 750 to 1,000°C, for a time t₁ in the range between t_1min and t_1max, wherein t_1min=23,500/(θ₁-729,5) and t_1max=4.946´10⁴¹´θ₁^-13.08, t₁ stands for the total time in the furnace, wherein the value θ₁ is expressed in °C, and t_1min and t_1max are expressed in seconds, then cooling the steel roll, sheet or workpiece at a cooling rate V_r1 to a temperature of θ_i, then holding the steel roll, sheet or workpiece at a temperature θ₂ from and including 100°C up to and including 500°C for a time t₂ between 3 and 45 minutes to achieve the content of diffusing hydrogen of less than 0.35 mln^-1, wherein said temperature θ_i is equal to room temperature and the roll, sheet or workpiece, after cooling to room temperature, is therein heated to a specified temperature θ₂, or the specified temperature θ_i is equal to the specified temperature θ₂, wherein said steel roll, sheet or workpiece comprises a mutually diffusive layer between the steel substrate and the coating, with a thickness between 2 and 16 mcm, wherein the mutually diffusive layer is the layer with the structure of ferrite α(Fe) containing Al and Si in a solid solution, wherein said steel roll, sheet or workpiece has an upper layer on the surface of the coating, containing aluminium oxide with a thicknesses greater than 0.10 mcm, wherein said cooling rate V_r1 is selected so that the sum of the proportions of the bainite and martensite areas is less than 30% of the steel substrate, after said cooling and until subsequent heating, or said cooling rate V_r1 is selected so as to obtain a ferrite-pearlite structure in the steel substrate after said cooling and until subsequent heating. The method for producing a press-hardened coated steel part includes processing the resulting sheet, roll or workpiece.

EFFECT: reduction in the processing time.

18 cl, 2 dwg, 3 tbl, 1 ex