A process for manufacturing a non-stamped prealloyed steel coil, sheet or blank, comprising the following successive steps: - providing a non-stamped precoated steel coil, sheet or blank composed of a heat treatable steel substrate covered by a precoating of aluminum, or aluminum-based alloy, aluminium-based alloy designating an alloy wherein aluminum is the main element in weight percentage, or aluminum alloy, aluminium alloy designating an alloy wherein aluminum is higher than 50% in weight, the precoating resulting directly from a hot-dip aluminizing process without additional heat treatment, wherein the precoating thickness is comprised between 10 and 35 micrometers on each side of the steel coil, sheet or blank, then - heating the non-stamped steel coil, sheet or blank in a furnace under an atmosphere containing at least 5% oxygen, up to a temperature θ 1 comprised between 750 and 1000°C, for a duration t 1 comprised between t 1min and t 1max, wherein: t 1 min = 23500 / θ 1 − 729.5 and t 1 max = 4.946 × 10 41 × θ 1 − 13.08, t 1 designating the total duration in the furnace, θ 1 being expressed in °C and t 1min and t 1max being expressed in seconds, then - cooling the non-stamped steel coil, sheet or blank at a cooling rate V r1 down to a temperature θ i, wherein said cooling rate V r1 is selected so that the sum of the area fractions of bainite and martensite is less than 30% in the steel substrate and so as to obtain a ferrite-pearlite structure in the steel substrate, after said cooling V r1 and before subsequent heating, then - maintaining the non-stamped steel coil, sheet or blank at a temperature θ 2 comprised between 100 and 500°C, for a duration t 2 comprised between 3 and 45 minutes, so as to obtain a diffusible hydrogen content less than 0.35 ppm, measured by thermal desorption analysis as disclosed in the description. - providing a non-stamped precoated steel coil, sheet or blank composed of a heat treatable steel substrate covered by a precoating of aluminum, or aluminum-based alloy, aluminium-based alloy designating an alloy wherein aluminum is the main element in weight percentage, or aluminum alloy, aluminium alloy designating an alloy wherein aluminum is higher than 50% in weight, the precoating resulting directly from a hot-dip aluminizing process without additional heat treatment, wherein the precoating thickness is comprised between 10 and 35 micrometers on each side of the steel coil, sheet or blank, then - heating the non-stamped steel coil, sheet or blank in a furnace under an atmosphere containing at least 5% oxygen, up to a temperature θ 1 comprised between 750 and 1000°C, for a duration t 1 comprised between t 1min and t 1max, wherein: t 1 min = 23500 / θ 1 − 729.5 and t 1 max = 4.946 × 10 41 × θ 1 − 13.08, t 1 designating the total duration in the furnace, θ 1 being expressed in °C and t 1min and t 1max being expressed in seconds, then t 1 designating the total duration in the furnace, θ 1 being expressed in °C and t 1min and t 1max being expressed in seconds, then - cooling the non-stamped steel coil, sheet or blank at a cooling rate V r1 down to a temperature θ i, wherein said cooling rate V r1 is selected so that the sum of the area fractions of bainite and martensite is less than 30% in the steel substrate and so as to obtain a ferrite-pearlite structure in the steel substrate, after said cooling V r1 and before subsequent heating, then - maintaining the non-stamped steel coil, sheet or blank at a temperature θ 2 comprised between 100 and 500°C, for a duration t 2 comprised between 3 and 45 minutes, so as to obtain a diffusible hydrogen content less than 0.35 ppm, measured by thermal desorption analysis as disclosed in the description.