Method for manufacturing a steel sheet for tin plated steel sheet and tin-free steel sheet each having excellent formability

A method for manufacturing a steel sheet for a tinplate or a TFS steel sheet each having excellent formability and a target hardness level (HR30T) in the range of 61±3 to 76±3, comprising the steps of:

• hot rolling a steel containing in terms of percent by mass:
• C:
• 0.0030 to 0.0060%,
• Si:
• 0.04% or below,
• Mn:
• 0.60% or below,
• P:
• 0.005 to 0.03%,
• S:
• 0.02% or below,
• Al:
• more than 0.005% to 0.1%,
• N:
• 0.005% or below,
• satisfying the following formula <1>, and
• the balance of Fe and unavoidable impurities, at a finish rolling temperature of an Ar3 temperature or above and a coiling temperature within the range of greater than 650° C. and not exceeding 750° C.;
• cold rolling at a reduction ratio of 85 to 95%;
• then annealing at a recrystallization temperature or above;
• and
• temper rolling or double reduce rolling to selectively manufacture a steel sheet having said target hardness level (HR30T) in the range of 61±3 to 76±3, and a sheet thickness of 0.2 mm or below, with a reduction ratio selected according to said target hardness level:
• 1.6×C×104+0.93×P×103≧70 <1>.