METHOD FOR PRODUCTION OF HOT-PRESSED PARTS FROM ALUMINIZED STEEL Russian patent published in 2020 - IPC C21D8/04 C21D9/48 C23C2/28 

FIELD: metallurgy.

SUBSTANCE: method includes provision for the presence of a furnace comprising N zones, wherein each furnace zone is respectively heated at a temperature setting value of Θ_1F, Θ_2F, ..., Θ_iF, ..., Θ_NF, production of sheet steel with thickness th, which is equal to 0.5–5 mm and containing steel substrate coated with preliminary applied coating from aluminum alloy, having thickness equal to 15 to 50 micrometers, wherein emissivity coefficient is equal to 0.15(1+a), wherein a is in range from 0 to 2.4, then cutting said steel sheet to produce steel workpiece with pre-applied coating, arrangement of steel workpiece in furnace zone 1 during time t₁, equal to 5 to 600 s, where Θ_1F and t₁: Θ_1Fmax > Θ_1F > Θ_1Fmin, wherein: Θ_1Fmax=(598 + Ae^Bt1 + Ce^Dt1) and Θ_1Fmin=(550 + A’e^B’t1 + C’e^D’t1), wherein A, B, C, D, A', B', C', D' are such that A=(762e^0,071th – 426e^{– 0,86th})(1 – 0.345α); B=(– 0.031e^{– 2.151th} – 0.039e^{– 0.094th})(1 + 0.191α); C=(394e^0.193th – 434.3e^{– 1.797th})(1 – 0.364α); D=(– 0.029e^{– 2.677th} – 0.011e^{– 0.298th})(1 + 0.475α); A’=(625e^0.123th – 476e^{– 1.593th})(1 – 0.345α); B’=(– 0.059e^{– 2.109th} – 0.039e^{– 0.091th})(1 + 0.191α); C’=(393e^0.190th – 180e^{– 1.858th})(1 – 0.364α); D’=(– 0.044e^{– 2.915th} – 0.012e^{– 0.324th})(1 + 0.475α), where Θ_1F, Θ_1Fmax, Θ_1Fmin is expressed in °Celsius, t₁ is expressed in s, and th is expressed in mm, conversion of steel workpiece with coating into zone of furnace 2, heated at setting temperature value of Θ_2F=Θ_1B, and holding steel workpiece with coating in isothermal conditions for duration of time t₂, wherein Θ_2F and t₂: t_2min ≥ t₂ ≥ t_2max, wherein: t_2min=0.95t₂* and t_2max=1.05t₂*, wherein: t₂*=t₁²(– 0.0007th² + 0.0025^th – 0.0026) + 33952 – (55.52 × Θ_2F), where Θ_2F is expressed in °C, t₂, t_2min, t_2max, t₂* – in s, and th – mm, conversion of steel workpiece with coating to further zones (3, ..., i, ..., N) of furnace for achieving maximum temperature of Θ_MB from 850 °C to 950 °C, wherein average heating rate V_a of workpiece in range from Θ_2F to Θ_MB ranges from 5 to 500 °C/s, arrangement of steel workpiece in press, hot forming of workpiece for part production, cooling part with cooling rate, providing microstructure in steel substrate containing at least one martensite or bainite.

EFFECT: elimination of melting during heating of coating applied on steel sheet at simultaneous achievement of high efficiency.

15 cl, 5 tbl