How to control and utilize the age hardening phenomenon of low-carbon steel in packaging steel strips?

How to control and utilize the age hardening phenomenon of low-carbon steel in packaging steel strips?
　　 Answer After normal annealing of low carbon steel, tertiary cementite and nitride will precipitate from α solid solution. At this time, the ferrite-based matrix can be heated to above the PQ line of the Fe-C phase diagram. After heat preservation, a single-phase ferrite structure is obtained and then quenched. Since ferrite does not undergo martensitic transformation, it is still a ferrite matrix at room temperature. Immediately after long-term natural aging at room temperature or artificial aging at 100-120℃, at this time, the carbon source? And nitrogen atoms will desolubilize from ferrite and segregate in the mesh of voids or dislocations. At the same time, e-carbides and e-nitrides are precipitated in a coherent form. At this time, the strength and hardness of the material increase while the plasticity and toughness decrease, and a yield plateau (also called age hardening) appears. For low carbon steel stamped steel sheet, age hardening will deteriorate the stamping performance, slip lines or wrinkles and orange peel on the surface. Therefore, the low carbon steel sheet should be cooled quickly after annealing to suppress the precipitation of tertiary cementite and nitride below the PQ line.
　　 low carbon steel and carbon-free maraging steel, their strengthening is achieved through the aging hardening process of supersaturated solid solution, it is Mn, Mo, Nb, Ti, A1 and other elements in the aging with carbon The form of nitrogen compounds is precipitated and strengthened. They have a hardness of about 30HRC in the quenched state, which can be cut, and then aged for 3-4h at about 450℃ to increase the tensile strength by 1-3 times and meet the requirements of performance.