Patent ID: 9689052
Date: 2017-06-27
CPC Classifications: C21D,C22C

Claim:
1. A very thin steel sheet consisting of, in mass %, C: 0.0004 to 0.0108%, N: 0.0032 to 0.0749%, Si: 0.0001 to 1.99%, Mn: 0.006 to 1.99%, S: 0.0001 to 0.089%, P: 0.001 to 0.069%, and Al: 0.206 to 1.99%; further consisting of one or both of Ti and Nb at Ti: 0.0005 to 0.0804%, and Nb: 0.0051 to 0.0894%, within the range of Ti+Nb: 0.0101 to 0.1394%; further satisfying the relationships of N−C≧0.0020%, C+N≧0.0054%, Al/N>10, (Ti+Nb)/Al≦0.8, (Ti/48+Nb/93)×12/C≧0.5, and 0.31<(Ti/48+Nb/93)/(C/12+N/14)≦2.0; having a balance of iron and unavoidable impurities; and having a thickness of 0.4 mm or less, wherein: a yield point elongation of a JIS No. 5 tensile test piece of the steel sheet aged at 210° C. for 30 minutes is 0.4% or less, in a Hyne test performed 10 times on weld-fabricated three-piece can bodies, a number of times that weld seam fractures are present is 2 times or less, wherein, in the Hyne test, the weld seam is pulled so as to tear the weld at a weld heat-affected zone, and a flange projection length limit is 3 mm or more, the flange projection being measured after die-flanging on the weld-fabricated three-piece can bodies.