Method for making a steel part of multiphase microstructure

A hot deep drawn part made of steel having a homogeneous multiphase microstructure throughout said part, said microstructure comprising ferrite, wherein the part made of steel is obtained by a process comprising:

• cutting a blank from a strip of steel, the composition of which comprises, in % by weight:
• 0.01≤C≤0.50%
• 0.50≤Mn≤3.0%
• 0.001≤Si≤3.0%
• 0.005≤Al≤3.0%
• Mo≤1.0%
• Cr≤1.5%
• P≤0.10%
• Ti≤0.20%
• V≤1.0% and
• the balance of the composition being iron and impurities resulting from the smelting;
• said blank is heated so as to reach a soak temperature Ts above Ac1 but below Ac3 and held at this soak temperature Ts for a soak time ts adjusted so that the steel, after the blank has been heated, has an austenite content equal to or greater than 25% by area;
• said heated blank is transferred into a deep drawing tool so as to hot-deep draw said part;
• and
• the part is cooled within the tool at a cooling rate V such that the microstructure of the steel, after the part has been cooled, is a multiphase microstructure, said microstructure comprising ferrite and being homogeneous throughout said part.