Steel Sheet for Formed Member Having Enhanced Ductility, Formed Member, and Method for Manufacturing the Formed Member

A formed member having enhanced ductility, the formed member comprising, by weight%, C:

• 0.1% to 1.0%, Si+Al:
• 0.4% to 3.0%, Mn:
• 0.1% to 5.0%, P:
• 0.0001% to 0.1%, S:
• 0.0001% to 0.03%, N:
• 0.03% or-less but not 0%, and the balance of Fe and inevitable impurities,
• wherein the formed member has a microstructure comprising by area fraction:
• 5% to 40% of retained austenite, 60% to 95% of martensite, and 10% or less (including 0%) of ferrite.

A method for manufacturing a formed member, the method comprising:

• performing a pressing process on a steel sheet comprising, by weight%, C:
• 0.1% to 1.0%, Si+Al:
• 0.4% to 3.0%, Mn:
• 0.1% to 5.0%, P:
• 0.0001% to 0.1%, S:
• 0.0001% to 0.03%, N:
• 0.03% or less but not 0%, and the balance of Fe and inevitable impurities;
• quenching the steel sheet to an Ms-Mf temperature range;
• and
• heating the quenched steel sheet to a temperature range equal to or lower than Ac1 and maintaining the steel sheet within the temperature range.

The method of 11, wherein the formed member further comprises at least one selected from the group consisting of (a), (b), (c), (d), and (e), wherein:

• (a) at least one selected from the group consisting of Cr:
• 0.01% to 2.0%, Mo:
• 0.01% to 2.0%, and W:
• 0.01% to 2.0%;
• (b) at least one selected from the group consisting of Ti:
• 0.001% to 0.4%, Nb:
• 0.001% to 0.4%, Zr:
• 0.001% to 0.4%, and V:
• 0.001% to 0.4%;
• (c) at least one of Cu:
• 0.005% to 2.0% and Ni:
• 0.005% to 2.0%;
• (d) B:
• 0.0001% to 0.01%;
• and
• (e) Sb:
• 0.001% to 0.1%.