Patent ID: 11920208
Assignee: ARCELORMITTAL
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 2:
3. The method according to claim 1, wherein the cold-rolled and heat treated steel sheet has a microstructure consisting of, in surface fraction:
between 10% and 45% of ferrite, the ferrite having an average grain size of at most 1.3 um, the product of the surface fraction of ferrite by the average grain size of the ferrite being of at most 35 μm %,
between 8% and 30% of retained austenite, the retained austenite having an Mn content higher than 1.1*Mn %, Mn % designating the Mn content of the steel,
at most 8% of fresh martensite,
at most 2.5% of cementite, and
partitioned martensite.