PURPOSE: To prevent intrusion of foreign matter into a molten steel and to obtain defectless boundary adhesiveness by specifying the concn. of O2 in a combustion gaseous atmosphere and preheating the surface of a cladding metal to be joined to a base metal.
CONSTITUTION: The cladding metal 4 (slab) for cladding is put into a casting mold 2 and a panel-shaped gaseous combustion heating body 5 is suspended in the mold 2 to heat the surface 41 of the metal 4 to be joined to the base metal. The gaseous fuel regulated in the air ratio so as to maintain ≤20% concn. of O2 in the combustion gaseous atmosphere of the combustion space S to be formed between the heating body and the cladding metal is supplied to the body 5. The gaseous fuel and air are supplied through an introducing pipe 7 to the body 5. The body 5 is quickly taken out of the mold 2 after the heating and the molten steel for the base metal is cast by bottom pouring into the mold while the joint surface of the metal 4 is in a prescribed temp. range to weld and join the base metal and the cladding metal 4. An inert or weakly reducing replacement gas is supplied through an introducing pipe 5 into the space in the mold in the preheating and casting stage.
MUGITA MIKIO
SUZUKI MAKOTO
TERADA OSAMU
MIZUOKA SEISHI
