Method of producing a phosphatable part from a sheet coated with an aluminum-based coating and a zinc coating

A coated steel sheet for press hardening comprising:

• a steel sheet;
• an aluminum-based coating;
• and
• a zinc coating over the aluminum-based coating, the zinc coating having a thickness less than or equal to 1.1 μm, the zinc coating being primarily zinc the coated steel sheet having a weight composition as follows:
• 0.24%≤C≤0.38%,
• 0.40%≤Mn≤3%,
• 0.10%≤Si≤0.70%,
• 0.015%≤Al≤0.070%,
• 0%≤Cr≤2%,
• 0.25%≤Ni≤2%,
• 0.020%≤Ti≤0.10%,
• 0%≤Nb≤0.060%,
• 0.0005%≤B≤0.0040%,
• 0.003%≤N≤0.010%,
• 0.0001%≤S≤0.005%, and
• 0.0001%≤P≤0.025%,
• amounts of titanium and nitrogen satisfying Ti/N>3.42, and
• amounts of carbon, manganese, chrome, and silicon satisfying
• 2.6
• C
• +
• Mn
• 5.3
• +
• Cr
• 13
• +
• Si
• 15
• ≥
• 1.1
• %
• ,
• a balance of the composition being iron and unavoidable impurities resulting from processing.