Abstract: A method of enlarging the width of a continuously cast strand comprising partially immersing a metallic joint having an I-shaped transverse cross-section in the tail end of a firstly cast strand which is downwardly moving or stationary in a rectangular mold cavity defined by narrow and wide pairs of mold pieces, hold the joint in position until the tail end of the strand is solidified, outwardly moving the narrow mold pieces to define the desired enlarged width of the strand, filling the so-formed openings between the strand and walls of the mold pieces with a refractory material and then with a metallic cushioning material, restarting the continuous strand casting process.