Twip steel sheet having an austenitic matrix

A cold rolled and recovered TWIP steel sheet having an austenitic matrix comprising by weight:

• 0.1≤C≤1.2%,
• 13.0≤Mn<25.0%,
• 0.1≤Si≤3.0%,
• 0.1≤Cu≤5.0%,
• S≤0.030%,
• P≤0.080%,
• N≤0.1%,
• 0.1≤Al≤4.0% and
• 0.1≤V≤2.50% in such way that:
• when the amount of Al<2.0%, the weight ratio Al/V is between 0.2 and 8 or
• when the amount of Al≥2.0%, the amount of V>0.25%,
• the remainder of the composition being made of iron and inevitable impurities resulting from elaboration.

22:

• A steel sheet according to claim 21, wherein the austenitic matrix further comprises one or more of
• Nb≤0.5%,
• B≤0.005%,
• Cr≤1.0%,
• Mo≤0.40%,
• Ni≤1.0%,
• Ti≤0.5%, and/or
• 0.06≤Sn≤0.2%.

A method for producing a TWIP steel sheet comprising:

• providing a slab having a composition including:
• by weight:
• 0.1≤C≤1.2%,
• 13.0≤Mn<25.0%,
• 0.1≤Si≤3.0%,
• 0.1≤Cu≤5.0%,
• S≤0.030%,
• P≤0.080%,
• N≤0.1%,
• 0.1≤Al≤4.0% and
• 0.1≤V≤2.50% in such way that:
• when the amount of Al<2.0%, the weight ratio Al/V is between 0.2 and 8 or
• when the amount of Al≥2.0%, the amount of V>0.25%,
• the remainder of the composition being made of iron and inevitable impurities resulting from elaboration;
• and
• thereafter processing the slab into the TWIP steel sheet, the processing including
• heating at a temperature above 1000° C. and hot rolling with a final rolling temperature of at least 850° C.,
• coiling at a temperature below or equal to 580° C.,
• first cold-rolling with a reduction rate between 30 and 70%,
• recrystallization annealing between 700 and 900° C.,
• second cold-rolling with a reduction rate between 1 to 50% and
• performing a recovery heat treatment.

35:

• The method according to claim 34, wherein the composition further includes one or more of
• Nb≤0.5%,
• B≤0.005%,
• Cr≤1.0%,
• Mo≤0.40%,
• Ni≤1.0%,
• Ti≤0.5%, and/or
• 0.06≤Sn≤0.2%.