Quenching degree (represented by surface Rockwell hardness HR30T) Represents the mechanical properties of the material. Under the same manufacturing conditions, it represents the material performance well. However, under different annealing processes (continuous annealing or hood annealing), the same quenching degree exhibits different strength and elongation. Due to the effect of the anvil, there is a certain difference between the measured value and the actual value when the substrate thickness is different. Due to aging, the quenching degree may also change.
Formability
In addition to withstanding severe deformation during processing such as drawing, general can and cap manufacturing can be done with tinplate. The performance should be uniform and the grain size of the material should be suitable (generally 7#~9# for tinplate). As the can-making speed increases, the material requirements include low performance fluctuation, small thickness deviation, and good plate shape, otherwise it may cause defects such as can jamming. In order to prevent edge lifting during can-making and stretching strain during stamping, the strain aging of tinplate should be small.
Directionality:
In addition to strict requirements for isotropy for DI materials, the requirements for directionality are not very strict in general can-making processes. However, for secondary cold-rolled tinplate, there is a large difference in performance between the longitudinal and transverse directions (larger asb and lower elongation in the transverse direction). The circumferential direction of the can body should be consistent with the rolling direction. For primary cold-rolled tinplate, it is best to make the circumferential direction of the can body consistent with the rolling direction when there is stretching deformation during expansion and drawing, which can reduce the occurrence of defects such as cracking and local deformation.
