COLD ROLLED STEEL SHEETS HAVING IMPROVED SPOT WELDABILITY AND METHOD FOR PRODUCING THE SAME

摘要

An extra-low carbon cold rolled steel sheet useful for use in automobiles and the like having an improved spot weldability is obtained by combinedly adding Ti, Nb and B in predetermined amounts to the extra-low carbon steel so as to control the amount of fine Ti precipitate dispersed in steel to the specified reasonable range. Furthermore, the spot weldability is improved by controlling the production conditions of the extra-low carbon steel sheet to specified reasonable ranges.