A higher work hardening rate grade is required for certain roll formed or stretch formed components.
Lower work hardening rate is needed for cold forging of screws, bolts and rivets.
Higher machinability needed, and the lower corrosion resistance, formability and weldability are acceptable.
Higher resistance to pitting and crevice corrosion is required, in chloride environments
Better resistance to temperatures of around 600-900°C is needed…321 has higher hot strength.
A lower cost is required, and the reduced corrosion resistance and resulting discolouration are acceptable.
A lower cost is required, and the reduced corrosion resistance and fabrication characteristics are acceptable.