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

Claim 8:
9. The method according to claim 7, 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 μm, a product of the surface fraction of the 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 0.3% of cementite, particles of the cementite, if any, having an average size lower than 50 nm, and
partitioned martensite.